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Discussion Starter · #1 ·
Problem: Starts up fine - idles fine - but take it out for a spin and it'll die pretty quick. Restarts again no problem after a few seconds - Repeat

Hey Y'all. I've read everything available on the forum regarding this issue, and found that this problem could be anything from the Catalytic converter to fuel pump to any sensor.
I just got the Jeep. PO was tired of messing with it, and "passed the torch."

I believe every sensor with the exception of the Coolant Temp Sensor has been replaced. New fuel filter, fuel pump, distributor, plugs, wires, all installed by PO.

A couple things I think are worth mentioning that may help:

It knocks a bit upon startup, and when it dies. Idles smooth. 140k miles on it.

The heater core has been bypassed with an elbow. In theory this shouldn't matter, but If someone has input I am all ears. (Coolant running a smaller loop causing some weird voodoo magic?)

The temp gauge never gets much above 100 degrees. (Possibly because it dies whenever it is on the road?) Even so, my assumption is that it should still run, but I don't know how the ECM reacts to this. (Stuck thermostat?)

The gas gauge pins itself to beyond full with the key on. (PO told me he had someone do the fuel pump/strainer. Maybe they messed that up and somehow it's causing my issue?)

I tested fuel pressure by putting a valve in the throttle body plug port. It tests at 18psi. (Book says it should be 15.) Zero pressure when key is off. 18psi with key on. It drops to 17 momentarily when I blip the throttle or increase RPMs.

I am picking up an ignition coil tomorrow to try. (the existing one "looks" new, but I feel like this may be the best bet right now.) At this point I feel like I'm just throwing money at it in hopes of getting lucky.

One other thing: I thought I had the problem sorted last week so I drove it to get emissions inspection done. It passed everything except had an EVAP fault. I found the rollover valve was broken and disconnected, so I repaired that.

Does passing emissions testing in CA. rule out the clogged catalytic converter theory? Or is it opposite, where a clogged cat would make it pass emissions because hardly any air is going out?

I can't get it to flash codes at me. (Either a burned out CEL bulb or?)

Seriously, thanks so much in advance for anyone's time in helping. I owe you all doughnuts.
 

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Had a similar prob with a cherokee before. Chased that damn thing for weeks. Replaced damn near every part trying to find it.
In the end I finally replaced the 2 last parts at the same exact time: temp sensor and the egr valve.
The cherokee I was working on had 2 temp sensors and I missed 1 initially.
The egr valve was old and original so it was due for a change. It was PACKED with carbon deposits! Try pulling yours and cleaning it with bottle brushes and carb/brake cleaner.
After replacing those 2 things it stopped doing it and ran like normal.
 

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Discussion Starter · #3 ·
Thanks so much for the reply! I checked the EGR valve with a hand vacuum pump. It definitely isn't doing it's job as it is stuck open. While I was there I traced the vacuum line coming off of it over to a valve near the battery. (Pic posted) now I see another problem. There is no line coming off the bottom of this vacuum valve. It is constantly sucking air through that open port. If the EGR line is disconnected it stops. Perhaps the PO knew the EGR was bad, so just unplugged something? Any idea where this missing line goes to? There's a check valve below near the canister that's open also, but this may be a drain?
Thanks a million!!!
 

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Sorry I can't help with your line routing, but a service manual should get you sorted. There should be links on the site?
No problem glad I could help. I know what its like to chase something in circles. The egr valves are often over looked on our vehicles and can cause issues.
 

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No hose needed to the bottom of the egr/canister solenoid. It's some kind of vent. Not sure about sucking but if your egr is stuck open it will certainly idle poorly. The other pic looks like the vent to the 4 wheel drive vacuum system. Again no hose necessary.
 

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Discussion Starter · #6 ·
Thanks for the replies y'all!
I *think I got it sorted out. I found that the PO had run a jumper wire inside the fuel tank, across the fuel gauge power to the pump power wire. (Pic below.) The orange fuel pump power had been cut up high so I never saw that initially.

I guess it supplied power for a bit and then heated up enough due to the small wire that it would quit working? In any case, I replaced the fuel pump assembly, and have done a few test runs with no problems. Fingers crossed.
 

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