4.0L Low Fuel Pressure

[sheepjeep]

01 xj with 4.0L


For a while now I have been running into heat soak issues where out on the trail revving the engine hard on an obstacle the engine will vapor lock and I spend a bunch of time often in awkward positions purging the fuel rail of air and letting it all cool down. Doing some research online seems like the conciseness is that there could be issues with the fuel pressure.


So I did a fuel pressure test and it is reading 30 psi with the motor running, should be 49 (+/- 5) psi, and it is holding that pressure of 30 for over 5 minutes with the engine is off. My first guess is either fuel pump or fuel filter. I just want to make sure that this is the right assumption before I go pull the tank down and just throw a pump assembly at it.

 

[Ecomike]

I believe the FPR is in the gas tank and part of the pump assy on the 01.
Could be an aftermarket fuel filter in line to check for, but I believe the only fuel filter is in the tank. The flex-fuel line in the tank may be going bad, loose, leaking...Could be a crushed fuel line between the tank and fuel rail!!!!! Check for that first!!!

But it sounds like the FPR which is in the tank (IRRC on 01) is bad. Use nothing but OEM or Bosch fuel pumps!!!! The rest are junk

 

[sheepjeep]

Thanks just checked the fuel lines look good except the evaporator line that goes from the tank to the canister has broken off from the canister