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Take good care of that AMC20............VERY hard to find.

I was actually buying the truck assuming it had a D35 in it and when I went to pick it up the PO was like ya it's got a AMC 20 in it....I was like Waaaaa . Then the icing on the cake was when I got it home and found the CC stamped on it.

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  • 4 weeks later...
  • 3 weeks later...

Well I have been taking vacation time for the past two weeks and I have been busy with automotive repairs here at the house. I deleted the Egr on my ford 6.0 and replaced the oil cooler while I was at it. I have worked on the Comanche alittle at a time and today I was able to dedicate most of the day to working on it. Last Monday my wife and I tested for spark and detected no spark at the plugs. I listened to the injectors and did not hear them clicking. My father inlaw felt like the ECU had went bad because my wife had smelt a burnt electronic smell when the jeep had quite her a few years back. We also tested the CPS and no voltage registered on my HF multimeter, I take that reading with a grain of salt given the tool I was using but we decided to get a new CPS anyway. My wife also changed the motor oil that day. Yesterday we picked up a salvage yard ECU. Today I unplugged every electrical plugin in the engine compartment and sprayed it with electronics cleaner allowed it to dry and then added some dielectric grease before I plugged them back in. I also refreshed all the grounds including the sensor grounds and the fuel pump ground. I replaced the battery cables and also added the two supplemntal chassis grounds cruiser suggest. I installed a new fuel filter and the junk yard ECU. Out of curiosity I took the cover off of the old ECU. I found two burnt circuits. I then then took the cover off the original ECU that my father inlaw replaced several years ago. It had one burnt circuit in the same place on the board as the ECU I just removed today. The red circle shows where the circuit board was burnt.

My father inlaw associated the use of the a/c with the ECU failure. As the a/c was in use both times the ECU was damaged in the past. I also took the cover off the new to us junk yard ECU, it looked good. I removed the CPS.

The wife brought home a new CPS and we will install it tomorrow and hopefully we will have a running Comanche!

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Installed the CPS today cranked it over and it did not start. Checked for fire and no spark to the plugs and none coming out of the coil. So I pulled the coil sanded the prongs and bent the receptacle slot thingy so they would grip the prongs tighter and reinstalled the coil. Had the wife crank it over and it fired! I got in the truck turned the motor over and gave her some gas and she roared to life. We drove it around the farm abit and it did not want to idle but after it ran for awhile it was purring like a kitten. Next is to get it road worthy in 2wd form. It will need a new battery and a set of tires. Once I finish the EFI of my cj5 I will start the 4wd conversion on the Comanche.

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Back to a no start condition. Only symptoms leading up to it was no idle when cold and high idle when warm. I am gettin Fire and fuel to the rail but I do not know what the fuel pressure is I will have to buy a fuel pressure guage. I can hear a very faint click of the injectors but not a definite spray. My first thought was IAC valve but I do not think it would cause a no start?

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I suggest posting a thread over on the MJ Tech forum for the no-start.

 

Here is a link to Cruiser's Renix tips if you don't have them handy: http://comancheclub.com/topic/36382-cruisers-renix-tips/

 

It sounds like you've already cleaned up your grounds and coil contacts.  If you haven't touched your C101 bulkhead connector, you might want to give Tip #2 a shot.  Shouldn't take too long, and a lot of important signals route through it.

 

Did you get a voltage reading with the new CPS?

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I suggest posting a thread over on the MJ Tech forum for the no-start.

 

Here is a link to Cruiser's Renix tips if you don't have them handy: http://comancheclub.com/topic/36382-cruisers-renix-tips/

 

It sounds like you've already cleaned up your grounds and coil contacts. If you haven't touched your C101 bulkhead connector, you might want to give Tip #2 a shot. Shouldn't take too long, and a lot of important signals route through it.

 

Did you get a voltage reading with the new CPS?

Thank you I have that page saved in my favorites. This truck does not have the C101 connector because it is a 89. I went to do the #6 sensor upgrade and it was already done. I didn't test the new CPS as I am gettin Fire to the plugs.

I really think I have a soiled fuel system. I got it started after some cranking and holding the throttle wide open. It blew a lot of white and blackish smoke at start up and would not idle. I drove about 1/4 mile down the road and when I gassed it hard it took off then back fired and sputtered then back fired again then died. I took the fuel filter off and back flushed it and what flushed out was some nasty looking, cloudy fuel with small particles. I still need to test fuel pressssure and that will tell me if I have a partially clogged fuel filter. I will probably put a new fuel filter on anyways. I will let you know what I find. Thanks!

Casualty of the back fire.

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Good luck man I had a similar problem and bad crap in filter and system had to get worked out disconnected fuel line by filter and let her spit crap out and put new filter on. By the way I converted my 1991 to 4x4 and love it! Best of luck!

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This truck does not have the C101 connector because it is a 89.

Ah, I got thrown by your username :)

Casualty of the back fire.

Ouch!

Oh lol Ya my name is from a 88 YJ I had. It was from New York and rusty as can be....around the bottom. Ya the blown muffler sucks because my wife's dad had just put new exhaust on before it quite him.

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Good luck man I had a similar problem and bad crap in filter and system had to get worked out disconnected fuel line by filter and let her spit crap out and put new filter on. By the way I converted my 1991 to 4x4 and love it! Best of luck!

Thank you for the well wishes. I am hoping I don't have to pull the tank but maybe best thing to do. I may try your method first and run the half tank of fuel out that I put in it and throw on a new filter.

Ic your from Gentry this jeep came from Elkins area, that's where my inlaws live. I am near Harrison.

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  • 3 weeks later...

Well over the long weekend I pulled the fuel tank off the Comanche.

 

 

There was some rubber pieces and some other gunk in the bottom of the tank but not really as bad as i had expected. I also noticed the strainer sock was off the pump inlet. So i drained the tank and sloshed out what trash i could. I put it all back together reinstalled and put a new fuel filter on.

 

 

Still no start. I have done some reading this morning and found a thread here on Comanche club where a guy had similar problem. He noted that when he finally pulled his pump and he also found the rubber pieces in the tank and that it was the seals from the old pump, once he installed a new pump it fixed it. I am getting spark I have verified this over and over, because I get paranoid about these renix electronics. Anyways I am going to pickup a fuel pressure gauge and see what I have pressure wise at the rail. I am getting fuel to the rail and I can hear the pump running but I am thinking similar prob that my VW Passat had, fuel but not enough pressure! I meant to test fuel pressure before i pulled the tank incase I needed a fuel pump but I guess I like doing things twice!

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Lol.. that bites man! Put a new pump in it if ya can! That many years it's shot if rubber in tank anyhow. It's amazing I will work on 1 thing and it ends up being 10 or more. Bites on the wallet!

I know what your saying, if it's 1 thing then its 10 more!

I am perplexed. I bought a fuel pressure guage and tested the fuel pressure. When the pump primed it read about 31psi. Then I cranked the engine over for a few seconds and checked the gauge and it read 34psi. From what I have read in the Haynes manual that within spec? Next logical thing be my injectors? I need to read up on how to bench test those I guess.....tomorrow I am going to check all the spark plugs for spark just to make sure and pull the vac line line on the FPR and crank to see what the fuel pressure goes to. According to Haynes it should go up to 39psi. I will also use my stethoscope and listen to injectors see if I can hear them click or spray. Any other suggestions?

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