20 Most Recent 1989 Jeep Comanche Questions & Answers

I take it that it cranks over but will not start. Spray some starter fluid into the throttle body. If it runs, you have a fuel problem. You may have disconnected the fuel system by unplugging a connector or grounding a wire blowing a fuse.

Sounds like a body ground, I would start there.

You must use silicone grease

on the relay there will be a small wire that gets power when you turn the key to the start position find that wire and connect it to the small terminal of the starter solenoid then if you get it right , when you turn the key to start, power will get to the starter solenoid , energize the solenoid and the starter will engage

dead short or wire in the wrong place behind the fuse box

Most vehicles have a high idle until the engine gets hot. As for your random problem, might want to check for any vacuum leaks that could cause this problem. When checking, best to do with cold engine. Start your vehicle and spray short amounts of starting fluid near vacuum hoses, if idle changes, you may have a leak. Keep away from exhaust manifold if at all possible. Also spray near intake hoses and air filter housing.

https://archive.org/stream/88FSM/mj1988electricalmanual_djvu.txt Hope this might help

fuel pump relay

Replace the crankshaft position sensor

they made over 5 million and google searches seems to find them all. LOL first hit. on google finds it,.. http://www.youtube.com/watch?v=X5HvYRcaL7c best answer is see alldata.com and not build motors with rumors. id never not fail to do that. (and win) listen to Colin Hill, 27yr bolts are C-R-A-P, (called END of life) they are not TTY and has nothing at all to do with this topic ill not list why.!.. but can if asked. my online fsm shows. updated proc. even more important is order. i sold my Comanche, they are rare and a great car. PU. circular pattern from center outward, right side first. 1191 is new head, 53005535

1. Install the cylinder head and bolts. The threads of bolt No. 11 must be coated with Loctite 592 sealant before installation. Tighten the bolts in 3 steps, using the correct sequence:
   1. Tighten all bolts to 22 ft. lbs. (30 Nm).
   2. Tighten all bolts to 45 ft. lbs. (61 Nm).
   3. Retighten all bolts to 45 ft. lbs. (61 Nm).
   4. Tighten bolts 1 through 10 in sequence to 110 ft. lbs. (150 Nm).
   5. Tighten bolt 11 to 100 ft. lbs. (136 Nm)
   6. Tighten bolts 12 through 14 to 110 ft. lbs. (150 Nm)

ill see if the old head is same. it is. try alldata.com and stop guessing and digging up rumors or post what are the top , 5 reason for new gasket failures. 1: not checked for warp, deck and head. then resurfaced. 2: using the old , bolts. dah? 3: wrong head gasket or not using a Felpro. using ebay china gaskets. 4: not using the steps in the FMS. 5:not getting head pressure checked.

no spark to all 6 cylinders, or just 2 ???????????????????????? did you check all fuses first?????????? did you check that the CEL lamp glows, key on? MIL lamp? if not? the main is dead, or fuse dead.(blown) ok this is the very very old and obscure Jeep Bendix/Renix system. the hard part is , it is NOT OBD1 engine yet, making diagnosis very hard. and no distributor. (new for MPI) is yours the 4.0 I-6 and is it the 1 year, MPI engine? WITH MAF SENSOR!! this is and AIR DENSITY SYSTEM unlike most other jeeps. 1989 - Changed to Renix MPFI. (read 4 injectors now>....) i owned a 88 Comanche, love it. 200,k miles i drove from 0 other that ISC motor, zero issues. mine was TBI , no MAF. NO spark.,? this MPI has a coil pack with 3 coils in side, and uses the famous. wasted spark design, even my new jeep v6 has this. the coil is driven by a separate ICM , ignition control module. The ICM, iis driven by the PCM(ECU) your car has a CKP sensor (crank) fitted to the BELL for the 3 marks, on the flywheel quote FSM. The Crankshaft Position Sensor (CKP) is secured by special shouldered bolts to the flywheel/drive plate housing. It is preset in its mounting at the factory and is non-adjustable in the field. uq: this means it tunes like a marconi radio, its not a hall sensor...!!! its just a coil with weak outputs. is it loose? id do not know where the CAm CMP sensor is. the online books mix 5 systems bad, this engine was EFI was a one year only system. (French) My wild guess is the CMP is this funny device, on the right side of engine, where the DIZZY USED to be. called the cam sensor. that too, must work and i think its a hall sensor and is very easy to test. sadly no OBD1 and no CEL: flash codes. to blink out, CMP/CKP dead. cranking just very old factory scan tool works again, all spark dead or only 2?

run fault codes and look for faulty TCM or reverse servo/ solenoid.

i had and 88. 4.0L I6 with the nasty Bendix-Renix EFI. love /hate that. sure when i bought mine new, got the FSM with it, (i demanded it) the books are IN CHUNKS, main book , no engine, nor tranny then had to buy 4L blue thin book and one for my Peugeot 5speed, (hate the clutch slave i do) ok , that take some may buys on fleabay to get all 3 books. so here is one source, one login and bingo. it's called alldata.com (no shill ) i like Mitchels,even better. http://www.scantool.net/software/alldata-diy-1-month-subscription.html log in, down load, or print as you want. or any jeep form real, this site here, X, is not. not at all ... x= here our mouse is... now. here...

look for asd relay try swaping the relays around make sure the ign switch is powering relays and dont forget make sure the grounds are clean and good and hooked up

The crank sensor is a good candidate. Pretty common failure on jeeps.To clarify, the fuel pump is on all time during engine cranking, and during engine running. When the engine cuts off, the pump will also be stopped. But, you will not lose pressure in the fuel lines and fuel rail immediately. The check valve in the pump is supposed to hold fuel pressure in the system for a good time-about 20 minutes. The pressure should bleed off very slowly.Your fuel pump and fuel system is probably good, but if you really lose prime (or pressure) that quickly, then there is a problem. Best way to check is with a fuel pressure gauge after the engine cuts out. Or, if you have the test port schraeder valve on the fuel rail (looks like a tire valve), you can use a screwdriver to press the center of the valve. If gas squirts out, you do have fuel pressure, prime is not lost, fuel system is good, and you can assume problem is in the ignition circuit, not a fuel problem. Probably the crank position sensor.Good luck, Casey.

You should have a vacuum line diagram under the hood of your car you can buy the haynes repair book for your vehicle at any autozone or advance auto someplace like that