I NSTALLATI ON - Howell Engine Developments, Inc.
Contents
1. for 2 BBL TBI to Jeep intake manifold a FIG 3 Mounted TBI with primary vacuum lines a FIG 4 Weld in bung for Oxygen sensor 18 MM thread FIG 5 gt Oxygen sensor mounted in bung welded into exhaust pipe near exhaust manifold a FIG 6 Assembled electric fuel pump and fuel filter with adapting reducers FIG 7 b Throttle linkage connected to ball on throttle lever plate lt FIG 8 10 air filter assembly available from GM parts FIG 9 m Wiring harness passing through firewall showing 112 hole grommet and mounting of fuel pump relay and power fuses a FIG 10 Wiring harness grounds attached to intake manifold to rear of TBI unit A FIG 11 Battery power and starter solenoid connectors attached to Jeep starter solenoid on fenderwell FIG 12 gt MAP sensor attached to firewall near brake master cylinder a FIG 13 Coolant sensor mounted in cylinder block water jacket on pre computer jeep models2. gas from spraying around the engine compartment Look at your SERVICE ENGINE SOON light when attempting to start for the first time The light should come on when the ignition is turned on stay on during cranking and go off when the engine starts IF THE LIGHT GOES OFF DURING CRANKING IT MEANS YOU HAVE POWERED THE ECM AND INJECTORS FROM AN ACCESSORY FUSE BLOCK TERMINAL AND THE ENGINE WILL NOT START Your switched 12v power must come from a terminal that is hot with key on and during cranking and goes off when the ignition is turned off INITIAL DRIVING IMPRESSIONS The calibration prom supplied with a CARB EO approved JP 1 kit is specifically designed to operate your Jeep in an emission legal mode using the following emission components and settings EGR operating by ported vacuum through the Dual CTO valve ported vacuum to the Jeep distributor set at 6 8 degrees BTDC initial timing at idle and a catalytic converter in good condition Proms for other kits are similar but may not be exactly the same This prom should be a near perfect match for your engine However the GM ECM has the ability to learn and adapt a new program to match your engine It does this by reading information from the Oxygen sensor and adjusting the calibration until it matches GMs original intent It will adjust this new program as weather barometer and altitude change and store it memory as long as the battery is connected and charged If you disconnect the
3. maintain good drive ability and help reduce emissions this heater system must remain installed and functional As an alternative it may be wired directly to 12 volt power source 3 2 NOTE MOUND a sufficient amount of automotive RTV sealer on the TOP of each Allen bolt head a 3 8 mound and allow to set up for at least 4 24 hours if possible so there will be no vacuum leaks Install the TBI unit with the supplied gasket and hold down bolts 3 Revise and connect vacuum lines as shown on the following vacuum diagram using the previously removed vacuum lines and plastic tees as required The canister located under the washer fluid bottle has 4 vent tubes EGR may be maintained as factory on earlier model non emission legal kits On JP 1 and emission legal kits the Dual CTO valve ports are shown in the figure below All vacuum ports on TBI unit are lettered on the actual TBI unit For earlier model Jeeps without Dual CTO valve you must acquire an OEM part PN J3238932 The Dual CTO valve is used in the JP 1 CA legal kits only if you do not have the CA legal kit you do not necessarily have to run the Dual CTO valve The stock CTO valve systems can be used as they were from the factory or they can be eliminated on the non emission legal kits Fitter lo Ported atmosphere Canigtar vacua purge contrat CTO vacuum connections a e INTAKE MANIFOLD F l re e 0 PCY VALVE DISTRIBUTOR AW v
4. manifold flange FIGURE 5 The supplied 18MM bung can then be welded into the exhaust pipe The Oxy sensor can be mounted at any angle depending on your ability to create the correct hole in the pipe for the bung NOTE If you do not have in house equipment to make the correct hole in the exhaust pipe and weld in the bung you may want to have this done ata muffler shop before starting the TBI installation When the bung is in place you may install the Oxygen sensor 5 FUEL LINES AND FUEL PUMP Before proceeding further in the engine compartment you should have the fuel pump and filter in place The fuel pump is an in line design that will maintain the 12 15 PSI operating pressure at all times The fuel pump electrical terminals are on the HIGH PRESSURE outlet end of the pump Assemble the fuel pump and filter as shown in FIGURE 6 using the supplied hose reducers and clamps The fuel filter attaches to the rear main fuel line with about 12 inches of flexible fuel line between cut off fuel line and the fuel filter The pump should be mounted inside the frame rail above the transmission shield plate or directly to the trans shield plate itself Use the supplied 1 2 clamp to mount the fuel pump against the frame rail or trans shield under the vehicle If your fuel line runs along the passenger side of vehicle you should be able to use one of the existing fuel line clamp holes to mount it If your fuel line runs along the driver s side of veh
5. manifolds have a suitable hole for the new coolant sensor Use Loctite or equivalent pipe sealer on the sensor Connect the harness to the coolant sensor This completes the connections on the engine Toward the passenger side of the firewall a separate branch tees off the main trunk and contains the fuel pump relay battery power and fuel pump power fuses These can be permanently attached to the engine firewall on the right side FIGURE 9 Also near this point of the harness the fuel pump power lead breaks out and can be routed to the fuel pump and connected with a two pin Weatherpack connector This lead contains power and ground for the frame mounted fuel pump The VSS is adapted to the transfer case speedometer cable drive output To install remove the speedometer cable and thread VSS in series of the transfer case and speedometer cable and attach VSS connector to harness 6 INSIDE THE VEHICLE Mount the fuse block and diagnostic connector along the bottom of the dash or on the heater housing CAUTION The ECM needs some air circulation for cooling so don t put it under the carpet Use a Radio shack or automotive bulb socket and 1 2V bulb for the SES check engine light and mount it in the dash 7 Using one of the single weatherpack connectors and terminals supplied and 16 or 14 gauge wire connect the ECM fuse block to a 1 2V source that has current when your ignition key is in BOTH THE CRANK AND RUN positions Not an acce
6. or air pump on early models and diverter valve Decel valve and bracket 4 amp 10 in vacuum switch assembly PCV solenoid Knock sensor Upstream Downstream amp Idle solenoid bracket Air cleaner stud bracket from rocker cover Throttle return spring bracket Fuel line bracket on block f Remove fuel and vapor return line from Jeep fuel filter to the point where it attaches to metal return line on driver s side of Jeep g Remove the carburetor Make sure the carburetor mounting surface is clean and free of any gasket material Cover open manifold to keep out debris When finished your engine should look like FIGURE 1 h Remove main fuel line from support brackets along the frame rail on the driver s side of vehicle Earlier models will remove main fuel line support brackets from top of frame rail near oil filter and under passenger side of vehicle i Cut main fuel line with a pipe cutter approximately 2 back of the rear side of the transmission shield and discard forward line Be sure to have some sort of plug to temporarily seal off the fuel line until fuel pump is installed fuel will continue to leak if not plugged INSTALLATION OF TBI AND ENGINE HARDWARE 1 Install the supplied 2 barrel adaptor plate FIGURE 2 using the Jeep 2 barrel carburetor gasket Use gasket and cap screws supplied Note the intake manifold heater on late models only When your engine is running and below 160 deg F the heater should be on to
7. EM carburetor These are no longer required due to the advanced engine control system capable of better pollution control in addition you enhance durability due to the use of genuine GM late model components that have been developed and thoroughly tested by GM as OEM parts on the 4 3L V 6 engine With the JP I EFI kit your Jeep will meet all EPA guidelines and California Air Resources Board CARB requirements up through Model year 1991 by qualifying for CARB EO Executive Order D 452 This makes it legal for distribution and installation in all 50 states NOTE TO BE FULLY EMISSION LEGAL YOUR JEEP MUST HAVE A PROPERLY FUNCTIONING CATALYTIC CONVERTOR EGR VALVE CANISTER AND PURGE SYSTEM PCV VALVE AND A VEHICLE SPEED SENSOR INCORPORATED INTO THE SPEEDOMETER DRIVE CABLE THAT TRANSMITS VEHICLE SPEED INFORMATION TO THE ECM The under hood vacuum diagram included with this kit is based on a 1990 Jeep Wrangler Earlier model years will vary slightly but all circuits are required to be emission legal Kit Components Two barrel TB unit with integral TPS and Idle Air Control JP 1 kit has E O tag Electronic Control Module ECM GM PN 1227747 Howell wiring harness connecting engine to vehicle ECM Calibration Prom matching TB to Jeep 258 CID in line engine inside ECM Cal pack L 6 for limp home operation inside ECM Manifold vacuum sensor MAP GM PN 16165793 Engine coolant sensor for ECM control GM PN 25036979 Exhaus
8. HOWELL ENGINE DEVELOPMENTS INC FUEL INJECTION APPLICATIONS I NSTALLATI ON MANUAL MODEL JP 1 EFI KIT FOR JEEP 258 CID 4 2 6 CVL ENGINES 1972 1991 THIS KIT IS LEGAL TO SELL DISTRIBUTE AND INSTALL ON VEHICLES IN CALIFORNIA UNDER CARB EXECUTIVE ORDER E O D 452 HOWELL ENGINE DEVELOPMENTS INC 6201 Industrial Wa Marine Citv MI 48039 Ph 810 765 5100 MAV 2000 INSTALLATION INSTRUCTIONS MODEL JP 1 TWO BARREL THROTTLE BODY FUEL INJECTION ON JEEP 6 CYLINDFR 258 CID IN LINE ENGINES The HOWELL Jeep EFI kit uses a new General Motors throttle body fuel injection unit from the 4 3L V 6 engine to replace your existing Jeep carburetor It is fitted to the stock Jeep intake manifold with an adaptor supplied in the kit and controlled by a GM vehicle ECM computer using a coolant sensor MAP Manifold Absolute Pressure sensor and heated Oxygen sensor for input information These components allow your Jeep to operate at the correct air fuel ratio for minimum emissions best power and good fuel economy This kit provides improved starting both hot and cold and immediate drive away without lengthy warm ups Off road maneuverability is greatly improved by eliminating troublesome stalls due to flooding or fuel starvation In addition to the above improvements the TBI kit simplifies the under hood area by removing many of the vacuum hoses and vacuum controlled emission devices formerly required to meet emission standards with the O
9. The HOWELL JEEP EFI kit is a bolt on conversion but if you feel that you may not have the mechanical proficiency to perform the changes then have an experienced mechanic do the installation Before starting the actual installation take the time to read these instructions completely During installation check off each step as it is completed Common sense and normal caution should always be followed when working on any vehicle especially when working with high pressure fuel Keep an ABC fire extinguisher available when working with gasoline When working under your vehicle always use proper jack stands Do not rely on a floor jack The amount of time it takes to install the kit may vary between 6 12 hours The Jeep has evolved during the years covered by this kit 1972 to 1991 Although these kits are engineered to work on all model years your vehicle may deviate somewhat in general arrangement and general controls Obviously an engine with a one barrel carburetor will have to be updated with a later model intake manifold Different harness designs are available for CU models and 1986 and later Wranglers The engineering and emission test mule for this kit was a 1990 Wrangler NOTE On pre 1981 non computer controlled or aftermarket exhaust vehicles you may choose to install the Oxygen sensor described in paragraph 4 of the component installation instructions first if it is to be done by an outside source 1 Raise hood to allow access to t
10. acu Schematic l Connect the purge signal to the dual CTO valve on the engine Tee the purge line into the PCV line which gets full time vacuum at port C on the TBI unit 3 8 diameter port Fuel tank vent line is already in place The final or carburetor bowl vent line on canister must be plugged or capped The EGR valve gets vacuum from the dual CTO valve The CTO valve gets vacuum from port A on the TBI unit The distributor vacuum is teed into the line from port A to the CTO valve Some earlier non emission models and non CA legal kits may perform better with inan old vacuum for distributor vacuum advance The map sensor gets vacuum from the rear of the TBI unit port F and DO NOT tee into this line it will be installed directly from the TBI unit to the MAP sensor ONLY 12 max length Any other vacuum requirements must be connected directly to intake manifold including transfer case vacuum switch AC controls brake booster etc The crankcase vent line from the rear of the rocker cover will attach to the bottom side of air cleaner for filtered air 4 OXYGEN SENSOR At this point you will want to install the bung FIGURE 4 that mounts the Oxygen sensor if you haven t already done so NOTE Model years 1981 to 1991 should already have oxygen sensor mounting bung in stock exhaust manifold Installing the bung can be done without removing the exhaust system Drill or burn a 7 8 hole approx 3 downstream from the exhaust
11. battery the ECM will lose the learned program and revert back to the original Howell JP 1 program However it will immediately start learning again as soon as you start driving the vehicle Any electronic or engine control problems can be diagnosed by a GM dealer or tune up shop using their computer diagnostic scanner that plugs into the ALDL or diagnostic connector near the ECM When diagnosing with a scanner enter the engine as an 88 or 89 GM light duty truck application The 4 3 V 6 engine code is Z When using other types of scan tool equipment you may use the third digit as C the eighth digit as Z and the tenth digit as J or K Our service manual also gives techniques for do it yourself diagnostics using a jumper the ALDL connector and SERVICE ENGINE SOON light SERVICE NOTES 1 Don t forget to install the new under hood decal showing the vacuum line schematic and CARB OE number and information included with JP 1 kits 2 Unless otherwise stated below follow Jeep OEM recommended service maintenance procedures and intervals 3 The kit assumes you have an engine in mechanically good shape no vacuum leaks at the intake manifold and no leaks at the exhaust manifold 4 There are no idle speed or air fuel ratio adjustments on the Howell EFI kits Only initial spark timing is adjustable Our recommended setting for good emissions and driveability is 6 8 degrees BTDC at idle with vacuum advance disconnected This setting is
12. d be reported immediately to the shipper and not Howell Engine Developments Inc Howell Engine Developments Inc is not responsible for any damages to equipment and possible liability injury that could result from improper use of the product Howell Engine Development s maximum total liability under any conditions is the repair or replacement of the product PRODUCT RETURN POLICY Most products can be returned for credit within 30 days of shipping All returns must be Aas new for maximum credit and free of modification and scratches A 15 restocking charge will apply to any used returned components in good condition and a 25 charge will apply to all components requiring repairs or unusable as returned All return shipping must be prepaid TECHNICAL ASSISTANCE Technical assistance over the telephone can be obtained from Howell Engine Developments Inc at 810 765 5100 between the hours of 8 30AM and 6 00PM Eastern Standard Time or Daylight Savings Time in summer months Ignition wiring circuit for 1981 91 Jeeps with Duraspark Ignition as modified for use with Howell EFI ie i li l ko f Coil Spl Ground F Bi 5 xa ce Splice oo O Soo Duraspark Ign Module Distributor 7 Engine Compartment JEEP L 6 TBI INSTALLATION a FIG 1 258 L 6 Jeep engine with carburetor components removed for installation of TBI kit FIG 2 gt Adaptor plate kit
13. d or starter FIGURE 11 The orange wire is batterv power and connects on the batterv side of the solenoid or the positive post of the starter The purple wire connects on the opposite side of the solenoid or to the starter solenoid post of the starter Connect the labeled white wire to the ignition coil negative terminal to pick up a tach Signal NOTE Multiple spark discharge ignitions require a special Tach filter to function correctiv Contact Howell Engine Developments if vou need one The Oxygen sensor wire should be l ng enough to attach to your previously mounted Oxygen sensor If necessary to extend it cut and solder splice on the harness side not the Oxy sensor lead wire Moving forward connect the 2 injector connectors at the top of the TBI and plug in the throttle position sensor and idle air control motor The MAP sensor connector branches out of the harness near the grounds and connects to your MAP sensor The MAP sensor can be mounted in any convenient location on the firewall however it should be mounted WITH THE VACUUM LINE POINTING DOWN and level with or higher than the TBI base FIGURE 12 The MAP sensor has its own vacuum tap at right rear of the TBI and NOTHING should be tee d into this line The coolant sensor is mounted using in an existing 3 8 NPT threaded hole on the left side of the engine which may have previously mounted a temperature controlled vacuum switch FIGURE 13 Models with water heated intake
14. e and the ECM doesn t know the engine is cranking See service note 5 above on aftermarket ignitions If pump is activated while cranking go to the next check step Check With air cleaner removed observe TBI injectors to verify if any fuel is being sprayed while cranking If not the fuel pump may not be primed Loosen the high pressure line on drivers side of TBI wrap a shop rag around it and activate the fuel pump by turning on the ignition key When fuel comes out re tighten clamp and try again to start engine If fuel spray is minimum tee into high pressure line and check fuel pressure It should be 11 12 PSI If no fuel comes out you may have a low voltage problem Using a voltmeter check from JP 1 fuse block near ECM to ground while cranking Compare with voltage across battery terminals while cranking They should be within 1 volt of each other If greater than 1 volt temporarily run a hot wire from ECM fuse block to battery and see if engine will start If so fix low voltage problem to ECM fuse block Check With air cleaner removed observe injectors to see if too much fuel is being sprayed If so hold accelerator fully open and crank This is called clear flood mode and injectors should cease to spray so that excess fuel can be cleared and the flooded engine started This condition can be caused if your bypass returns fuel line is restricted or plugged Temporarily correct for this by attaching a length of hose to the bypa
15. e back of the computer connector Number 47 light green black or orange on some models will be cut and spliced into 59 orange at or near the junction in the main harness Number 18 purple will be cut and spliced into the ignition module jumper wire supplied in kit Some models require a direct splice or connection at module connector purple wire For models 87 91 use the procedure in the next four lines as described To install jumper wire remove the two 2 and 4 pin connectors from the ignition module located under coolant bottle and raise connectors and harness to locate 4 pin connector Release connector lock and install jumper wire in the open or C position of the four pin connector Close lock and feed jumper wire through harness to junction and splice into 18 purple Re connect 2 and 4 pin connectors to Dura spark module NOTE MAINTAINING WIRES NUMBERED Al OR A57 VELLOW WILL GIVE THE OPTION OF USING ONE OF THESE WIRES AS YOUR SWITCHED 12 VOLT POWER SOURCE The remaining wires from computer harness connector will not be used and they will be cut at the main harness trunk and removed To maintain manifold heater trace the blue wire from manifold relay located to the right of the battery and apply switched 12 volts hot with ignition on for proper operation Another method would be to run direct power to the heater using a switch to operate it manually The remaining relays and diagnostic connector can either be removed or kep
16. he left side firewall to the vicinity of the vapor and fuel vent steel lines Connect the bypass return to the line formerly used to return vapor from the Jeep fuel filter to the tank Install hose clamps at all connections both pressure and return and tighten Do not over torque clamps as this will destroy hose and will not improve the seal 6 JEEP THROTTLE LINKAGE attaches to the ball stud on the throttle lever plate FIGURE 7 There is sufficient torsion return spring on the 2 barrel TBI units so you should not need a separate return spring Check for wide open throttle and bend the vertical linkage if necessary to clear the EGR valve to achieve WOT Some later model Jeeps will require the throttle ball stud to be installed inward on the throttle plate The throttle link plate may need to be slightly ground on one edge to clear the vacuum fitting on the intake manifold or remove power brake fitting from intake and mount a new fitting in place of the longer fitting to give adequate clearance to the throttle linkage plate for full throttle movement 7 AIR CLEANER GM makes an excellent 10 open element air cleaner that fits the TBI properly and clears everything It is available under Part 1234208 1 or 12342082 FIGURE 8 K amp N makes an excellent 9 open element air cleaner under K amp N part numbers 60 1120 and 60 1110 also K amp N 7 diameter 2 high 60 1320 and 7 diameter 3 high 60 1330 Moroso has an 8
17. higher than the original OEM recommendation 5 AFTERMARKET IGNITION SYSTEMS If you are running an aftermarket ignition system MSD Mallory Jacobs etc you might not have a coil signal that will trigger our built in tach filter If your engine will not start and you have one of these systems contact Howell Engine Developments at Ph 810 765 5100 for assistance TROUBLE SHOOTING PROBLEM DESCRIPTION amp SOLUTIONS SYMPTOM Engine cranks but won t fire or start Check To see if there is spark while cranking This can be done with an inductive timing light or with a spark plug connected to a plug wire grounded against any metal surface on the engine If there is spark go on to the next check If not fix Check Observe to see if service engine soon light comes on when ignition key is turned on If not harness may not be powered up or grounded correctly Check grounds fuses and power with a voltmeter or test light If powered up and grounded correctly SES light should come on and fuel pump activated for 3 seconds Check Observe Aservice engine soon light while cranking If it goes off during cranking you are connected to an accessory terminal on the Jeep fuse block Correct by running switched 1 2V wire to an ignition power source Check Observe or have someone under vehicle verify whether fuel pump comes back on while cranking engine If not you are not getting a tach reference from your tach lead connected to the coil negativ
18. his will keep you from being stranded in event of sensor failure until you can get the trouble corrected The Service Engine soon light will come on anytime any back up features are activated Your vehicle ECM is GM part number 1227747 This is the ECM used in most light duty truck TBI engines from 1987 through 1991 If replacement is necessary it is available at any GM dealership It is a rugged proven design the result of millions of GM dollars spent on development It has the ability operating in closed ioop to learn a calibration that perfectly matches your engine and retain it in memory An added benefit of the GM ECM is its ability to alert you to a potential sensor or electrical problem by turning on the SERVICE ENGINE SOON light built into your harness This light and a common paper clip will allow you to discover and diagnose any problems retained in the ECM memory Procedures for this are outlined in any GM TBI service manual or the Howell HP TBI service manual that accompanies your TBI kit The CALIBRATION PROM supplied with your kit is mounted inside the ECM under a plate retained by two screws There is only one emission legal prom for California Jeeps In the event you need to replace it follow the instructions below 1 Remove the ECM from its mounted location Depress the latches and remove the harness ECM connectors one at a time from the ECM 2 Remove the ECM cover retained by two screws 3 Remove the large
19. icle you could mount it to the trans shield Measuring on the driver s side of shield 3 3 4 from the front of vehicle to the back and 3 2 from rocker panel to the center of vehicle you can locate and scribe a mark for drilling a 1 4 hole into shield to mount fuel pump clamp and pump The fuel filter will have adequate support from the connecting hoses so it does not need to be clamped down NOTE IT IS NECESSARY TO FILTER THE FUEL BEFORE THE PUMP TO PROTECT IT FROM FOREIGN MATTER HIGH PRESSURE PUMPS ARE EASILY SEIZED AND WE DO NOT WARRANTY AGAINST THIS FAILURE IT IS ALSO NECESSARY TO MOUNT THE FUEL PUMP AT OR BELOW MIDLEVEL OF THE FUEL TANK THAT IS IF YOU ARE LOCATING THE PUMP IN AN OTHER THAN RECOMMENDED AREA Using the supplied 5 16 fuel hose run your high pressure fuel line from the fuel pump to driver s side fitting on the back of the TBI unit Route the fuel line carefully away from sharp edges and the exhaust system and secure it with some of the supplied tie wraps and mounts If you prefer you can fabricate a 5 16 steel line for your high pressure fuel but it must connect to the fuel pump with a short length of rubber line to prevent noise transfer from the pump Since the TBI system operates on only 12 PSI fuel pressure it is not necessary to have high pressure hose or aircraft type threaded connections Your bypass return fuel line is either 1 4 or 5 16 hose and routed from the right rear of the TBI along t
20. nuts located on the engine side of the firewall near the battery to pull computer out for access to the harness connector bolt of the computer Remove harness connector to allow computer to be removed from the dash To remove harness from vehicle the defroster duct must be removed to prevent damage and allow for easy removal through firewall The rubber grommet willbe pushed through firewall with a screwdriver and then cut through on one side to be reused on the new harness Once harness is removed from within the vehicle lay the connector over the intake to begin eliminating excess wiring Three wires will remain along with the manifold heater relay wiring from main harness on firewall the temperature sending unit purple which is located on the left rear side of the valve cover The manifold heater pink and manifold heater switch light green black located on intake below and behind carburetor opening Remove main harness away from firewall by unfastening mounting clips and strip covering back to expose wiring at the computer harness and main harness junction Refer to page 12 for a diagram showing the complete wire up for the Jeep Dura Spark Ignition System Some earlier models Jeeps do not have the numbered computer connector the same color codes or Dura Spark Module Connector Located on the back of the computer harness connector are the wire location numbers To reveal connector number locations remove the black retainer clip from th
21. op of engine and disconnect the battery 2 Most Jeeps are tall enough to just simply crawl underneath without raising the vehicle If not jack up left side of Jeep and support with jack stands Raise high enough to allow access to the Ll I frame rail and main fuel line to enable fuel pump installation in this location Some earlier model Jeeps will require the right side of the vehicle to be raised for pump access Fuel lines usually run down the frame rail on opposite side of the exhaust system REMOVAL OF NON REQUIRED PARTS FROM CARBURETEDENGINE a Remove the mechanical fuel pump from the carbureted engine Install the supplied fuel pump block off plate and gasket from your kit b Remove and discard the air cleaner Thermostatic Air Cleaner System THERMAC c Remove all vacuum lines and connectors from carburetor only 2 will be re connected as indicated by an asterisk Idle solenoid vacuum line 4in Hg beige vacuum switch connector Carburetor bowl vent line to canister plug canister nipple PC V Canister vacuum line Thermal vacuum switch and distributor advance vacuum line Stepper motor connector WOT switch connector Electric choke heater connector Throttle return spring d Remove and discard the fuel line and filter from fuel pump to carburetor e Disassemble remaining vacuum lines and air pump hoses if so equipped and the following emission controls Upstream check valve and Downstream check valve pulse AIR system
22. plete the adjustment NOTE If none of the above troubleshooting resolves your problems contact Howell Engine Developments Inc Phone 810 765 5100 or FAX 810 765 1503 or email us at mhowell howell efi com OoOoKROW PD co CON WARRANTY Howell Engine Developments Inc products have a 30 day unconditional guarantee The product can be returned within 30 days from shipping for a 100 refund less shipping charges provided that it is returned post paid without damage or modification and has not been installed The CARB EPA exemption granted to the JP 1 kit mandates that no modifications can be made to its components no reprogramming of its computer and no deviations is made from this instruction manual without consent from Howell Engine Developments Inc and or CARB EPA as required Howell Engine Developments Inc assumes no responsibility for the function or suitability to task of any modified kits Howell Engine Developments Inc Warranties this product against manufacturing defects for the period of 90 days from date of shipping This warranty covers all parts but does not cover outside labor to diagnose or repair without specific prior approval from Howell Engine Developments Inc This warranty does not cover any failures caused by misuse accidents or shipping incidents Warranty failures will be repaired or replaced at the discretion of Howell Engine Developments Inc Any damages that may have occurred during shipping shoul
23. r of the two cal proms by carefully prying and lifting it straight up 4 Install the replacement cal prom It will only go in one way so it can t be installed wrong Replace the cover 5 Reverse the removal sequence and reinstall the ECM in its vehicle mounting location CAUTION Do not remove the cal prom with harness still connected to the ECM It may be damaged by 1 2v power that is always present in the vehicle harness when the battery is connected INITIAL VEHICLE START UP AND OPERATION With everything mounted and connected the vehicle should be ready for start up When ignition key is first turned on listen for fuel pump operation It should turn on for 2 or 3 seconds and then the ECM will turn it off until you engage the starter The first time ignition is turned on it may not be sufficient to fill the TBI and fuel line with fuel Cranking for a few seconds should complete the filling The engine should start up and smooth out after a few seconds to purge air from the injectors Check for fuel leaks and make sure none of your altered wiring or fuel lines are in a position where the exhaust system heat can damage them MAKE SURE THE COOLING SYSTEM IS FULL If the engine does not start immediately it may be because the fuel pump cannot displace the air in the line and prime itself Loosen the high pressure line at TBI and cycle the pump by turning on the ignition key to displace the air Wrap a rag around the fitting to prevent
24. ss return outlet of the TBI and running it to a 5 gallon can If engine starts and runs with proper fuel correct problem with restricted bypass return Bypass return pressure should not exceed 5 6 PSI SYMPTOM Engine starts but runs poorly at idle or dies Check System voltage at ECM fuse block Must be within 5V of battery voltage while running Possibly poor connection through Jeep firewall to Jeep fuse block or inadequate wiring to ECM fuse block Temporarily run bypass 14 gage wire from battery to ECM fuse block to see if that improves running If so supply ECM fuses power from battery through an ignition controlled relay Check For possible rich condition and black smoke at idle and low speeds Test for excess bypass return pressure causing TBI fuel pressure above 12 PSI Check If you are having problems with decel off idle stall and idle drop or low rolling idle refer to Idle Air Adjustment Instructions Idle Air Adjustment Instructions Before beginning adjustment grind the throttle stop screw plug flat and drill into the plug to allow a T 20 Torx driver to access the screw 1 Jumper A and B terminal of the ALDL connector Turn ignition key on engine off Disconnect 4 pin idle air control connector from the TBI unit Remove jumper from ALDL connector Start engine While idling adjust throttle stop screw to increase base idle rom as desired Turn engine off Reconnect idle air control connector This will com
25. ssory position which loses power during cranking This completes the electrical harness installation CAUTION CHECKING FOR FULL SYSTEM VOLTAGE it is not unusual for older Jeeps to experience a battery voltage drop passing through the firewall to fuse block area THE GM TBI SYSTEM MUST HAVE FULL BATTERY VOLTAGE TO OPERATE PROPERLY Check your voltage to the ECM and compare it with your battery voltage at the battery If it is more than 1 VOLT less than battery voltage you will need to correct voltage loss If this is not possible run a separate battery power source to the triple fuse block through an ignition controlled relay or toggle switch on the dash Low system voltage will result in hard starts and poor idle problems CALIBRATION PROM AND VEHICLE ECM The brain and control center of your new electronic fuel injection is the Electronic Control Module ECM It amp ontrols the amount of fuel delivered at any time based on inputs from the Oxygen sensor coolant sensor MAP sensor and throttle position sensor The correct fuel settings are pre programmed into the calibration prom and match your engine closely for everything to work correctly The JP 1 prom is the only emission legal prom for California Jeeps The calibration prom and a smaller removable chip called a Cal pack are pre installed in your ECM The Cal pack contains back up or limp home programs in case one or more sensors fail and the ECM cannot do its proper function T
26. t Oxygen sensor amp 18MM mounting bung Single wire oxygen sensor GM PN 25166816 JP I Kit has heated oxygen sensor GM PN 25312184 9 Electric fuel pump high pressure in line HED PN FP 257 ONDA PWN 10 High flow fuel filter in line Fram PN G3802A 11 Fuel line kit 12 Fuel pump relay GM PN 14089936 13 Vehicle Speed Sensor HED PN VSS263 JP 1 Kit only Page 8 Section 5 14 Small parts kit for routing and mounting components 15 Service manual basic troubleshooting and operating information 16 Under hood label Vacuum Diagram and E O ID JP 1 Kit only THIS SYSTEM IS BASED ON THE PRODUCTION GM Chevrolet or GMC THROTTLE BODY FUEL INJECTION AND ELECTRONICS USED FROM 1986 91 ON 4 3 V 6 ENGINES ALL BACKUP SYSTEMS AND ON VEHICLE DIAGNOSTICS FUNCTION SIMILAR TO THOSE MODEL YEAR PACKAGES THIS SYSTEM DOES NOT CONTROL SPARK TIMING AS ON GM ENGINES BUT RELIES ON A TACH SIGNAL FROM THE JEEP ELECTRONIC IGNITION FOR RPM INPUT TO THE ECM Installation procedure will be separated into the following categories Preparation of Jeep for TBI installation Removal of non required parts from carbureted engine Installation of TBI and engine hardware Installation of Electronic components and wiring harness Calibration PROM and vehicle ECM Initial vehicle startup and operation Initial driving impressions Tuning and troubleshooting CON ONnAWN PREPARATION OF JEEP FOR TBI INSTALLATION
27. t in place Replace the covering of the main harness and attach to clips on firewall Remove Coolant Temperature Switch Knock sensor and Oxygen sensor Install new Coolant sensor in Coolant Temp switch mounting hole and new Oxygen sensor into the exhaust manifold Leave the Dual CTO valve in place Knock sensor mount hole will remain open 72 81 For models without computer controlled carburetors there is room to mount the ECM in a vacant space above the heater ducts For 1972 80 models you will need a 1 1 2 hole in the firewall FIGURE 9 This can be done with a hole saw or Greenlee sheet metal punch The harness can be fed through this hole from inside the Jeep A rubber grommet is supplied with the kit to seal around the harness and hole in the firewall In models that have computer controlled carburetors you will use the existing harness grommet and mount the ECM in the same location as the OEM ECU was mounted using either Velcro or existing brackets 1 The harness grounds attach to an existing threaded hole towards the rear of the intake manifold FIGURE 10 and locate the harness position at the back of the engine The engine trunk portion moves forward between the rocker cover and TBI from that point After the grounds are secured route the labeled purple and orange wires to the starter solenoid on the right hand fender well or to the starter These wires each have a lug that attaches to the stud on either side of the solenoi
28. x 66 3 10 INSTALLATION OF ELECTRONIC COMPONENTS AND WIRING HARNESS The Howell HP TBI Wiring harness supplied with your system does all the interconnecting wiring from the engine sensors and TBI unit to the GM vehicle ECM It is designed to fit your Jeep with a minimum of left over wire when properly installed CJ and Wrangler harnesses are different in comparison The ECM fuse block and diagnostic connector will be located under the dash If you happen to have the OEM California emissions model Jeep the MCU could be located in the engine compartment near the front drivers side area NOTE THIS SECTION OF INSTALLATION WILL NOT APPLY TO THOSE JEEPS THAT DO NOT HAVE COMPUTER CONTROLLED CARBS THE DURASPARK IGNITION ON NON COMPUTER CONTROLLED CARB SYSTEMS ARE ALREADY WIRED DIRECTLY FROM THE DISTRIBUTOR TO THE MODULE Skip to 72 81 On models equipped with computer controlled carburetors proceed as follows Remove far right instrument cluster bezel 3 screws along the top and 4 along the bottom of glove box door Remove middle instrument cluster bezel 3 screws along the top and 3 along top of stereo and heater controls If equipped with A C remove 4 screws under the dash along the A C vent duct and gently lower the duct away from dash Remove stereo away from dash also Remove the four glove box mounting screws that are located on the back of the outer glove box ears and remove glove box Remove computer mounting screw and bracket Remove the 2
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