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fuel pump works sometimes
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scottaucoin
New User
May 13, 2014, 2:36 PM
Post #1 of 2
(1590 views)
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fuel pump works sometimes
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I have a 1991 jeep wrangler yj 2.5lt with 125000 miles. The jeep runs fine most of the time but for some reason the fuel pump cuts out and the motor will not crank. After sitting a while the jeep will run again. I have changed the fuel pump twice ,replaced the wiring harness, and had the computer reworked. Any help would be much appreciated.
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Hammer Time
Ultimate Carjunky
/ Moderator
May 13, 2014, 10:33 PM
Post #2 of 2
(1578 views)
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Re: fuel pump works sometimes
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All "crank, no start" conditions are approached in the same way. Every engine requires certain functions to be able to run. Some of these functions rely on specific components to work and some components are part of more than one function so it is important to see the whole picture to be able to conclude anything about what may have failed. Also, these functions can ONLY be tested during the failure. Any other time and they will simply test good because the problem isn't present at the moment.
If you approach this in any other way, you are merely guessing and that only serves to replace unnecessary parts and wastes money.
Every engine requires spark, fuel and compression to run. That's what we have to look for.
These are the basics that need to be tested and will give us the info required to isolate a cause.
1) Test for spark at the plug end of the wire using a spark tester. If none found, check for power supply on the + terminal of the coil with the key on.
2) Test for injector pulse using a small bulb called a noid light. If none found, check for power supply at one side of the injector with the key on.
3) Use a fuel pressure gauge to test for correct fuel pressure, also noticing if the pressure holds when key is shut off.
Once you have determined which of these functions has dropped out,
you will know which system is having the problem.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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