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91 Pioneer 4.0 running issues


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So basically went out to my truck one morning, turned the key over , it started than died a few seconds later. Tried again it felt and sounded like no fuel. Put two gallons in. tried again and nothing. Just turning over but trying. Came back the next day to it, started it , ran for a few seconds, than died. Same thing. So had a fuel filter kicking around. Put that on no difference. Checked spark and I have spark. Checked and I'm getting fuel on the rail. Havnt put a pressure gauge on it yet though. Decided to do the tps . Changed it out. Than it started and ran for 10 seconds perfect, but than it went to a real low idle and almost stalled out. Than it jumped to a high idle . It did this cycle about three times than stalled. Tried again back to just starting for 2 seconds. Finally tonight I changed the cps. Still no change. Starting to rip my hair out with this one. Sorry for the long rant.

Jason

91 Pioneer 4.0 metric ton

automatic 4x4

78,000

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So checked the codes. Here's what I got

35

Cooling fan relay.

Check relay and circuit.

checked fuse box and relay isn't even there

33

Air conditioning clutch relay.

Wiring to A/C clutch fault.

truck doesn't even have ac

12

Battery disconnected.

Battery or power to the ECM disconnected in the last 50 key cycles.

 

I left the fuel pressure guage at work so ill get to that tomorrow. Hopefully won't be raining and I can check some grounds as well

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The code 33 was likely the last one, yes? I've read that in a non-a/c Jeep it can be the end-of-codes code. My MJ has a/c, and I get a 55 code as end of codes. You didn't get a 55 so I'm assuming that's what's happening with that one.

 

I doubt the cooling fan relay issue is your problem, unless you overheated and blew your head gasket or something... Wouldn't hurt to check for cross-contamination of fluids (oil+coolant) or check compression.

The code 12 seems to be something my truck threw out whenever there were codes to throw. While yes, my battery cables were/are pretty $#!&ty, it only ever gave the code 12 when other codes were present or if I had just had the battery disconnected for one reason or another. 

 

Check fuel pressure as well anyhow.

 

Jeep Driver's MAP sensor theory could also be something to look for. I would have expected a code for that, but your motor may not be running long enough for it to actually throw one. If you've got a buddy with a decent running XJ, you could always swap the map sensors to see what happens.

 

This is completely unrelated to your issues, but your set of codes is exactly what I got from my Lada today and forgot to look up. I'll go do that. Hope you find your problem!

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It's been quoted on here, but I don't trust my memory of them, so I won't post them to avoid confusion. But I will go look them up and post if you don't find them first. 

There's one pressure with the engine running, and one with the engine running and the fuel pressure regulator's vacuum line unplugged. Don't know if you'll be able to get a good reading if you can't really keep the engine running. I would assume the one with the vacuum unplugged would be the same weather or not the engine was running, though.

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