Jeep died while driving but now runs fine, fuel issue?

[Red91Laredo]

I was driving about 8 miles from home the other day when my '91 XJ (4.0, AW4, 242) randomly died as I went around a right hand turn at about 20 mph. It cranked fine but would not restart. Gas gauge was at 1/8 and the gas light was not on, but I thought maybe the gauge was not reading accurate; so I went and got a gallon of gas and put it in the tank but the Jeep still would not start.

I went to an auto parts store around the corner and was going to get a plug wrench to check spark, but realized a can of starting spray would be a cheaper and easier way to see if it was a spark or fuel issue. I had a friend crank the Jeep over while I cracked the throttle body open slightly and gave it a shot of starting spray and it immediately fired up and ran for a second. We got it to start a couple more times to confirm it would run with the spray, so I figured it was not getting fuel for some reason, although I could hear the pump priming when the key was turned to run.

I had the Jeep towed home and I didn't touch it for a couple days when I tried to start it, just thinking wouldn't it be funny if it starts right up, and sure enough it did. I let it run for several minutes and it sat and idled fine, all gauges normal, etc. I shut it off and restarted it a couple times with no problems and then drove it around the block with no problems.

I've looked under the hood for any loose wiring or anything obviously wrong but everything looks fine, my rig is pretty well maintained. I've driven it a mile or two from my house and have had no other problems, it starts and runs normally, idles fine, heavy acceleration to 60 mph it runs strong, etc. But I'm afraid to take it too far from home because I don't know why it died and wouldn't restart randomly, and I assume that eventually it will do it again.

Any ideas what it could be or suggestions on what to check? Does the CPS or any other sensor that affects fuel delivery start to fail intermittently before it dies for good? I'm thinking the fuel pump is ok but something was either causing it not to get power while cranking or something was causing the injectors not to fire.

The Jeep has 187k and the 4.0L is stock, under the hood is pretty much all stock in fact other than than a ZJ 130 amp alternator I added a while back. I've had it for 3 years and 42k miles and it's never not started on the first try and always ran well so I'm kinda stumped on this.

 

[8Mud]

If it stalls out when you let your foot off the gas pedal, like when slowing for a corner, it could be sticky IAC. If the IAC sticks shut, it will only start if you give a little gas pedal while cranking. If the IAC sticks shut and you crank it without giving pedal you can flood motor, which can just aggravate the issue.

I'm not sure if the 91 has an EGR or not, if it does a sticky EGR may also be an issue. If it sticks open the motor can die at idle.

 

[Red91Laredo]

When it died, I did try cranking it while depressing the pedal, both partway, and all the way to the floor (I remember hearing somewhere that if you flood an EFI motor trying to start it, doing that will help... I don't know if that applies to our XJ's, I just tried it because I was running out of ideas). I can see how if I had flooded the motor cracking the TB and using some starting spray could have helped get it started again, but I'd think that then it would just continue running?

I'll check my IAC and clean it out if need be and do some searching on whether or not I have EGR on my '91.

It just runs so well now (totally back to normal) that I feel like it must be an electrical/sensor that was causing it not to get fuel momentarily. I know the CPS is often responsible for random dieing/no start issues, but it controls both fuel & spark, correct? My thinking is that it should not have ran on starting spray if my CPS was being flaky?

I'm still wondering if maybe it's possible that the Jeep was just really low on gas after all- when it died, I coasted to the left side of the road, since it was the only safe place I had enough momentum to reach. I stopped with the Jeep pointing downhill and leaning to the left. Maybe it's possible that even though there should have been 2-3 gallons in the tank, all the gas was just out of reach of the fuel pickup? I'd think the gas tanks in these rigs would have some sort of baffle to prevent this sort of thing, but perhaps not? Anyone ever have their XJ stall while off roading with less than a 1/4 tank of gas?

 

[tjmotter]

If your CPS was bad you would not have had any spark so this seems fuel related. Perhaps your regulator (that small device at the front end of the fuel rail) is going bad? You might want to check your fuel filter as well.

 

[Shorty]

the small fuel hose in the tank that connects the pump to the rest of the sending unit is a known weak spot. It dries out over time and lets the fuel from the pump leak back into the tank instead of flowing to the engine.

The most common time for it to present itself is going around a corner with only a couple gallons of fuel........ sound familiar??