6.2 Dies

[HH]

The 6.2 in the Grand Cherokee dies once in a while after letting off the fuel pedal. I can come up to a stop sign and it will die, and sometimes when I stomp the pedal from idle and lift off quickly it dies. This does not happen all the time, seems to happen more when it is cold. Restarts no problem. Any ideas?

[DmaxMaverick]

Sticky governor (internal) or pump going south. At zero throttle input while the engine is on compression (being pushed by the vehicle, or idling down from higher RPM), the governor reduces fueling to zero. It should come back up to idle fueling as soon as the RPM nears the idle speed.

A "tired" IP in concert with any other system weakness can also be suspect. Make sure the fuel filters are fresh and the tank is venting properly (fuel filler cap).

You can try a heavy dose of a "cleaning" additive, and/or a lubrication additive. 2 cycle oil works as good as any lube additive, and may be better in this case. Some will recommend ATF, but I suggest it only as a last option.

[john8662]

Check your fuel pressure from the lift pump, this can be done at the outlet on the fuel filter.

A dead lift pump will also cause the issue where it'll die on deceleration. Been there done that one one of my N/A 6.2's.

[HH]

Truck has new filters, and new electric lift pump. Lift pump is a 1993 electric brand new. IP had been sitting awhile, came off government vehicle with low miles, I think less than 60k. I'll try a dose of some cleaner. Tank vent could be an issue, as I did not change the cap on the tank, cap is still stock for gasoline. Thanks for the help.

[Robyn]

IP likely has issues as described by Maverick.

Depending on the year of the IP it could even be one that had a "Flex ring" in it. (early 6.2's had these)

Failure of the flex ring can cause all sorts of wierd crap to happen.

Missy

[DmaxMaverick]

Start by replacing that gasser fuel cap with the correct Diesel cap. They vent very differently, and can directly cause the problem you describe.

[argo]

Listen to Robyn and DmaxMaverick. The flex ring can do it and so can the wrong fuel cap. When I was in college I had a diesel Olds (similar I.P.) that had this problem. I lost the fuel cap, and I took one from my friend's Camaro (it was broken down in his back yard). I figured "A gas cap is a gas cap". I was wrong. I would stall, sometimes restart had, and have no power. I'd release the cap and hear a whoosh of air entering the tank, and suddenly, it would run like a thousand bucks. (In hindsight, I bet the timing chain was stretched and the I.P. timing was retarded, and the EGR was choking the engine, so it didn't run like a million). My pump had already gone through he E.I.D. ring deal by the time I got the car, but when my grandfather owned the car, it has similar problems until the ring got fixed.

[HH]

Problem seems to have gone away. Drove the Jeep about 50 miles this week and did not die once. My luck seems to be getting better. Thanks for the help.

[DmaxMaverick]

That's great. Keep your fingers crossed. What did you do?

[HH]

That's great. Keep your fingers crossed. What did you do?

Just drove it around :rolleyes:. I did change the fuel tank cap, but that was after driving it around ?? Guessing governor in the pump was gunked up, seems to idle better now too. Could there still have been some air in the system from changing the IP and filters? Thanks!

[DmaxMaverick]

Just drove it around :rolleyes:. I did change the fuel tank cap, but that was after driving it around ?? Guessing governor in the pump was gunked up, seems to idle better now too. Could there still have been some air in the system from changing the IP and filters? Thanks!

Sure. That's as good an answer as any. Could have been more than one issue, too.