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94 xj issue - Fuel???

DarkNipz

NAXJA Forum User
Location
AZ
Hello all,
I am having an issue with my 1994 4.0 4x4 XJ. What happens is after long time running the engine will not go past X RPMS when in Drive. It starts at 4500rmp and the longer I drive it the more it goes down. I have had were it would not go over 1700RPM in drive. when I get on it when it is having this issue, it almost seem like i has a rev limiter. If I put it in neutral it will rev up fine. The only way I have found to by pass this issue temporarily is to turn it off and let it sit for 5-10min. Then it will run normal for 15 to 20 min.

Other info
Just replace the tank due to it rusted and started to have a slow leek.

when this first happen I replace the fuel filter and let it sit over night. Next time out 4x4 trip it started to have issues on the way home.

I can hear a sound coming from the fuel line, like there is air in it or the pump it hesitating. Was thinking about changing the fuel pump but figured I would get some help first.

I have not seen the temp gauge go over 210.

Thanks for any help.
~Darknipz
 
Have you checked the fuel pressure on the fuel rail when this is happening? Sounds like a fuel pressure issue or vapor lock.
 
Excessive heat around the fuel lines causes vapor lock. I don't know if a regular tie pressure gauge would work for fuel, but there is a valve on the fuel rail. Maybe it's a tool you can "rent" from autozone. You should check the pressure when it's cold and running well then again when the problem occurs.
 
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