driggs
NAXJA Forum User
- Location
- Morgantown, WV
I've got one of the troublesome 2001 XJ's (226k miles, 4.0L, 4WD, AW4 auto, ABS, A/C) with the "heat soak" P303 issue. I've installed the heat insulator sleeve on injectors 3 and 4, as recommended in the TSB, but it never solved the vapor lock on hot startup trouble. I had always assumed that my fuel pump check valve was leaking more pressure than normal, and always turned the ignition ON, OFF, ON, OFF, ON, START as a poor man's workaround.
This morning, after a long weekend of driving with no problems, including 2+ hours last night in very heavy rainstorm, it refused to start; turned and cranked but refused to start. I've been searching up and down
and similar symptoms point to fuel pump/filter/valve, or possibly crank position sensor.
I put a fuel pressure gauge on the fuel rail schrader valve, and it shows that when the fuel pump primes, pressure goes up to 42PSI with the Jeep off.
I fed it some ether in the throttle body, gave it some throttle while trying to start and managed to get it started, albeit sounding "starved". Fuel pressure at idle showed a solid 49PSI as expected; turn the Jeep off and it drops instantly down to 42PSI. I cannot get it to start without giving it gas, but with some accelerator pedal on start, I can get it going.
I fear that I need to replace the fuel pump, which is located inside the fuel tank on the '01 XJ. Can anyone recommend some good, easy troubleshooting for a not-so-skilled mechanic to diagnose? I'm not sure where to go next to figure out if the fuel pump is the culprit... no obvious fuel line leaks. Possible red herring: my oil pressure gauge recently started reading MAX, though I figure I just need to replace the pressure sending unit (again!).
If I do need to replace the fuel pump (of if I have to drop the fuel tank, I figure I should replace it while I'm there), is this Bosch unit all I need to do the job? BSH N69316
THANKS!
This morning, after a long weekend of driving with no problems, including 2+ hours last night in very heavy rainstorm, it refused to start; turned and cranked but refused to start. I've been searching up and down

I put a fuel pressure gauge on the fuel rail schrader valve, and it shows that when the fuel pump primes, pressure goes up to 42PSI with the Jeep off.
I fed it some ether in the throttle body, gave it some throttle while trying to start and managed to get it started, albeit sounding "starved". Fuel pressure at idle showed a solid 49PSI as expected; turn the Jeep off and it drops instantly down to 42PSI. I cannot get it to start without giving it gas, but with some accelerator pedal on start, I can get it going.
I fear that I need to replace the fuel pump, which is located inside the fuel tank on the '01 XJ. Can anyone recommend some good, easy troubleshooting for a not-so-skilled mechanic to diagnose? I'm not sure where to go next to figure out if the fuel pump is the culprit... no obvious fuel line leaks. Possible red herring: my oil pressure gauge recently started reading MAX, though I figure I just need to replace the pressure sending unit (again!).
If I do need to replace the fuel pump (of if I have to drop the fuel tank, I figure I should replace it while I'm there), is this Bosch unit all I need to do the job? BSH N69316
THANKS!
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