2000 XJ idles briefly then dies
#1
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2000 XJ no codes, no CEL. Sat for a long time. Starts for a second then dies. Occasionally will idle for a few seconds then dies, also dies if touching the throttle pedal. Twice is ran for a short time, accelerated, and once I even drove it for 0.5 miles (today). Swapped fuel pump relay with AC relay then also with O2 relay. Made no difference. I'm thinking it's the fuel pump, but that's a pricey shotgun diagnosis and a bit of work. There's fuel at the schrader valve, but no fuel pressure now. A few days ago it idled for a few minutes, and it had 45 psi at the schrader valve. Looks like there is no serviceable fuel filter? I see the evap canister under the car, but no fuel filter. Any thoughts or hints are appreciated.
#2
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Year: 1988
Model: Cherokee (XJ)
Engine: 4.0L
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When you first turn the key to ON (not start), do you hear the FP hum for a second or two then stop? Connect your FP gauge again. Turn the key to on. What's the fuel pressure? Leave the key on and FP gauge attached (pump should have stopped). Does the fuel pressure slowly drop? If it does, you have a leak (maybe an injector). If not, crank to start it and watch the fuel pressure. If it starts, keep watch the gauge. If it dies, note if the pressure dropped before it died. Is there fresh gas in the tank?
A vehicle that sits for a long time can develop other issues. Bad gas, corrosion in electrical components, swollen/cracked hoses, etc. Have you already ruled out those?
I'm going to assume it's not the immobilizer since you were able to drive it a short distance.
A vehicle that sits for a long time can develop other issues. Bad gas, corrosion in electrical components, swollen/cracked hoses, etc. Have you already ruled out those?
I'm going to assume it's not the immobilizer since you were able to drive it a short distance.
#3
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Can't hear for crap, so I climbed under while someone turned key to run. Fuel pump whirs for a second or two. No fuel pressure at schader valve, the needle does not move. Had person cycle key several times with fuel pressure gauge connected, no pressure. Fuel does come out of schrader valve when removing. I put 4 gallons of fresh fuel in the practically empty tank before I started all of this.
If I cycle the key three times before starting, it seems to run for a millisecond. Is there something that would cause the fuel pump not to come on after the initial start cycle? Does the vehicle use an oil pressure switch to determine the engine is running and keep the fuel pump on?
If I cycle the key three times before starting, it seems to run for a millisecond. Is there something that would cause the fuel pump not to come on after the initial start cycle? Does the vehicle use an oil pressure switch to determine the engine is running and keep the fuel pump on?
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From your description you don't have fuel pressure at the valve. You hear the fuel pump prime fore a second or two and then shuts off- thats normal and means you got power to it that makes the pump run- the pump itself might not be working correctly though. Or you have a blockage to the fuel line in front which might be less likely without a separate fuel filter.
The fuel pump runs 1-2 seconds and then shuts off unless attempting to start. Once the PCM sees a certain rpm via the CPS , it'll fire the injectors and spark and cause the engine to run. Oil side of things has no input in this.
The fuel pump runs 1-2 seconds and then shuts off unless attempting to start. Once the PCM sees a certain rpm via the CPS , it'll fire the injectors and spark and cause the engine to run. Oil side of things has no input in this.
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Year: 1988
Model: Cherokee (XJ)
Engine: 4.0L
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Like Roler said. The FP would likely overheat from running with no fuel flowing through it so the PCM primes the fuel system, and shut off after 3 secs if it doesn't get a signal the crankshaft position sensor.
The fuel pump has a little strainer "boot" on the end. If that fell off or is damaged, you could have sucked debris into the pump.
Since the pump is on top of the tank, you're likely going to have to drop the tank to further diagnose. Another approach some take is to cut an access hole in the floor, then patch it.
The fuel pump has a little strainer "boot" on the end. If that fell off or is damaged, you could have sucked debris into the pump.
Since the pump is on top of the tank, you're likely going to have to drop the tank to further diagnose. Another approach some take is to cut an access hole in the floor, then patch it.
#6
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Thanks Roler and Saudade. I ordered a fuel pump, spanner tool, and straps. I went with the Delphi. I'll update this week after replacing. It's acting like a clogged fuel filter or not enough gas, but I can't imagine that 4 gallons is not enough.
Last edited by dernt; 08-04-2024 at 10:31 AM.
#7
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Update: Removed the fuel tank today. It must have had about 10 gallons in it. Drained 8 gallons after dropping it, and there's still some sloshing around. The fuel pump has a pentastar on it, so maybe it's original at 340k miles. Parts arrived, so reinstall tomorrow after work.
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Saudade (08-05-2024)
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#8
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Can someone confirm that there is no other fuel filter in a 2000 XJ except for the tank strainer? Removed fuel pump. Strainer was detatched and at the bottom of the tank. Mostly dissolved. Green brown slime at the bottom of the tank. Cleaned and reinstalled. I'm afraid a lot of the tank crud got into the fuel system. Where is the fuel filter???
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No separate fuel filter in the 97+ - 99, and I assume not on the 00/01 either.
The strainer at the pump is the filter
Not bad if it's the OE pump, 340K miles!
The strainer at the pump is the filter
Not bad if it's the OE pump, 340K miles!
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Saudade (08-07-2024)
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Saudade (08-08-2024)
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