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Old 06-28-2008, 04:51 PM   #1
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Fuel Pump Question. Jeep wont start

I have a 1991 jeep wrangler that i drive that does not start. i sometimes have a problem with the fuel pump not turning on and the jeep not starting, but once i hear it turn on it starts right up (usually) now, i tried to start it after about 2 months of no use and heard the fuel pump go on but the jeep still wont start. How can i test the fuel pump? Or how can i test to see if gas is getting to the engine?

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Old 06-28-2008, 05:34 PM   #2
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there should be a valve on the fuel rail that you can plug a pressure gauge on if you have one. when the pump doesn't turn on while you crank, you need to know if power is at the pump at that time. if it has power, and no pumpy, then the pump is bad.

but if it isn't getting power when not coming on, something else. now, hearing it come on, and not starting still could be pump if it isn't pumping enough pressure, since it sounds like its been on the way out. also good idea to replace fuel filter if its old, to rule out clogged filter when the pump is coming on.

also check grounds, and relay for when it doesn't come on. hopefully they're both the same problem, just a bad/weak fuel pump. good luck. oh yeah, welcome to the forum.

good idea to check spark when it doesn't start, eventhough it sounds like just fuel related.

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Old 10-15-2008, 11:23 AM   #3
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What did you do to fix this? My 1990 2.5 will start fine if the pump comes on. When the pump, which has already been replaced ,doesn't come on with the ignition switch turned the fuel gauge pegs to full. Starting without fuel of course is impossible. Could it be a sending unit in the tank or maybe a computer problem?
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Old 10-15-2008, 11:43 AM   #4
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ok right beside the fuel tank,drivers side, there is a connector unplug it and check for 12 volts. if you got it then its in the pump, if not, go upstream to the relay under the hood. check the relay, it could be intermittent so it might show 12 sometimes and others not (sometimes the pump will work, others it won't) its the characteristics of relays. anyways there should be two relays on the battery tray, a pre-ignition one to prime and another is a start/run which will run it the whole time, just pull them and replace if you need to.
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Old 10-15-2008, 11:44 AM   #5
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ohh wait time oiut, i am sorry i thought you had a 90' so it might be diff, is yours multi port fuel injection or tbi?
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Old 10-15-2008, 12:55 PM   #6
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90 4 banger is tb injected
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Old 10-15-2008, 01:19 PM   #7
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ok so same as my jeep just go on with what i originally said
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Old 10-24-2008, 03:44 PM   #8
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I have a 91 wrangler that has been stutering as if the motor shut on and off and now it has stopped when I was on my way to get a new fuel filter. The fuel filter is replaced now but still wont run it sound like the fuel pump comes on but want second openion. also earlier that day the stereo syst. started haveing issues could it b the relays and how can I test one?

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