Jeep sputters out and dies

Liberated

Liberated

TJ Enthusiast
Joined
Aug 23, 2018
Messages
119
Location
Northwest Ohio
Help! '03 sport, 4.0, manual. In a bit of a pickle. Went snow wheeling last weekend, and started having problems running. I don't know if this makes a difference or not, but just in case I'll say it, I hit the governor like 7 times on the drive up.

So while we were wheeling, I was idling at the bottom of a hill waiting on someone to make it over and the Jeep puttered and died. When I tried to restart, it did, but acted like it was out of gas. After that it would turn over but not fire. First we thought vapor lock. But we couldn't get anything at the valve. We turned the key on, and heard the pump run, but not for more than a second or two. We scratched our heads, pulled the o2 sensor to release backpressure, and rolled the Jeep down to flat ground to get out of the way of a snowmobile. We shut off all electronics, pulled the drl connector, then pulled the relay and jumpered the pump. It ran just fine, so we cranked her and she started back up. Then we put the relay back in and it ran fine. So we shut her down, put the oxygen sensor back in, and and fired her up. No problem.

Half hour later it did it again. Once again on a slight incline. We rolled it back down to flat ground, pulled o2 sensor, shut everything off, and she fired up.

Took her into town and a shop tested the alternator, because a buddy had a suspicion I would have never come to. They tested it at 13.8 volts. They all agreed that the alternator was just not putting out enough juice, but I was still not convinced. The battery alone should be enough to run the pump, right? Still, my alternator was under warranty at home so I decided to try to drive it.

Well I drove it two hours to my dad's house, and it occasionally sputtered along the way, but did 75 just fine. Stopped for gas before finishing the drive to my place(another 2 hour drive), and it wouldn't start up. I shut off the lights, and radio and all(except cb), and it started up and ran smooth. Keyed the mic and it died. Did it again, same result. Killed the cb, and tried again, and it started, but sputtered out before I got out of the gas station. Ran to town for an alternator, when I got back to my Jeep a half hour later, it started and made the 3 mile drive to my dad's place fine. In the morning I replaced the alternator, then drove 2 hours home without trouble.

Today after work, I drove all around trying to find a homeless guy shelter, and after I got him settled, tried to drive home. It sputtered out and died.

So now, I have a problem that sometimes when my Jeep gets warm, it doesn't give me fuel, and it appears to be electrical... I'm sitting here disabled waiting for the engine to cool to see if she'll start and get me home. What is going on?

Only thing I can think is a bad ground. Would there be one that might cause this? Please help. Everything I have is breaking and my brain is getting fried.
 
Hmmm, starting simple I would look for a bad ground, or perhaps try splicing in a secondary ground to the fuel pump, I had a pick up once that would crap out at idle, but then if I would turn on the wipers a few times it would start again, I think why it ran ok when traveling was going down the road the pump was under more load hence pulling harder at the ground, or perhaps it never lost contact long enough to notice. Either way I added a secondary ground and it was fine, it's a cheap place to start too.

Question when it does this, does it even try to start while its cranking?
 
The first time it fires and putters like it's emptying the fuel from the rail, but then it just cranks after that.

Does anyone know of a chart or diagram of all the grounds in a TJ?

My other idea ties back to an s10 blazer I had back in high school. The starter would die once the engine was hot on a warm day. Had to wait for it to cool, then it would start right up. Anyone ever heard of a fuel pump acting the same when it starts going bad? Pump motor gets warm and won't work until it cools, kind of deal...?
 
Liberated said:
The first time it fires and putters like it's emptying the fuel from the rail, but then it just cranks after that.

Does anyone know of a chart or diagram of all the grounds in a TJ?

My other idea ties back to an s10 blazer I had back in high school. The starter would die once the engine was hot on a warm day. Had to wait for it to cool, then it would start right up. Anyone ever heard of a fuel pump acting the same when it starts going bad? Pump motor gets warm and won't work until it cools, kind of deal...?
Click to expand...
Hi,
Had the same problem with a garden tractor. Three shops said it was fixed each over$100. Finally asked a neighbor who likes to tinker and within a half hour he found a small tear in the diafram of the fuel pump which apparently only opened up once them motor got hot. New fuel pump, end of problem. BTW neighbor was a microbiologist. Lol.
 
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Liberated said:
The first time it fires and putters like it's emptying the fuel from the rail, but then it just cranks after that.

Does anyone know of a chart or diagram of all the grounds in a TJ?

My other idea ties back to an s10 blazer I had back in high school. The starter would die once the engine was hot on a warm day. Had to wait for it to cool, then it would start right up. Anyone ever heard of a fuel pump acting the same when it starts going bad? Pump motor gets warm and won't work until it cools, kind of deal...?
Click to expand...

The site below is the service manuals by year. It has a wiring diagram for all the wiring in the jeep.

http://www.jeep.on-line.no/documentation/TJ/Jeep_TJ.htm
 
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Sorry I haven't updated where I'm at. Kind of forgot about this post, as I'm in the midst of putting out about 100 fires right now...

Currently: I have the service manual. I've got good ground at the fuel pump connector(pins 3+4) and can show good voltage to the fuel level sensor(pin 2), but when it dies I'm getting no power to the pump itself(pin 1).

Aside from that, I've checked and cleaned engine and body grounds, and replaced battery terminals with milspec terminals. I cannot seem to find anywhere there ever was a frame ground, and best I can tell the wiring diagrams don't seem to clarify where I would actually find one. Think just for the heck of it, I make make up a ground strap to the frame.

I've checked fuel pump and ADS relays. I think the ads is kicking in from what I can tell. Going to hook it up to a diagnostic machine this afternoon. I'm wondering if my PCM is jacked up...
 
Sorry for the lack of update. Shortly after the last post, it wouldn't even crank over anymore. I finally gave up and sent it to a shop. Here's what they came up with:

1) fuel pump relay was bad (I had swapped it with another when trying to diagnose, so maybe they were both bad?)

2) crankshaft position sensor was bad (that same shop replaced it less than a year before... This time I told them only use Mopar)

3) starter motor went bad (this is probably true, after all the mud she went through last summer)

I don't know if it was really a mix of problems, and I had more than one relay bad, or if I just got lucky, but it has run ever since.

Now, just before I left for Moab in the end of May, I ran my codes, and came back with crank sensor bad at PCM. Now I'm wondering if I have a bad pcm, or if that code is just still hanging around from the old problems.
 
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Assuming you just cleared the code and maybe it was just not cleared from previous work. Glad everything else worked out!! I'm looking at poss replacing fuel pump/relay too, few issues here on fuel delivery, ie sputtering at high rpms, and gauge error, slow start on 2nd try, etc.
 
I thought I had reset the codes. Between that and the fact this code specifically says "at the PCM" I'm a little worried I've gotten lucky since the new CPS, relay, and starter.
 
This is above my pay grade but just curious for my own edu...did you have a CEL or just find the codes with a code reader? And if you used a code reader, did you clear all the codes with the reader, and then this popped up again? Again, it's above my KB but maybe someone will jump in here with something. It's a stretch and I may be wrong but seems like I've read elsewhere that when you change some of these components it takes a while and some driving for the PCM to "re-learn" the driving systems, which implies that it is somewhat intuitive? I have no idea but maybe since is seems to drive well and not throwing CELs at you, continue clearing the codes and maybe it will find it's habit? Hopefully someone way smarter than me will chime in here since I too am very interested in this.
 
My check engine light is always on for evap stuff, and the occasional misfire. But I did have the shop do one final check before I headed off to Moab, and that's when we found the PCM code. I'd never seen the PCM code before, and they seemed a little surprised by it, like they hadn't seen it last time. I'm pretty sure the light was off for a couple days after they fixed it, so I think they cleared it. From the little I understand though, I think you're on the right track that the computer stores info and adjusts over time.
 
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