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Q: fuel pressure leak?

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boy do I have a headache of a problem.I have a 1993 jeep grand Cherokee.Runs great but developed a fuel leak in back by fuel pump.Replaced the lines.Starts and runs fine for about two minutes then pressure seems to build and fuel pours out over the top of the fuel tank.Its very difficult to pinpoint exactly where it comes from,but it seems like some kind of back pressure is causing it to leak somewhere above the tank.Any hints?Thanks so much ahead of time.You help us all out so much.Been reading the posts,and just joined the community.

My car has 200000 miles.
My car has an automatic transmission.

A: Hi there, and thanks for writing in. Than...

Hi there, and thanks for writing in.

Thank you for all the kind words as well, it means a lot. As for your car, you have a send line and a return line. You’ll need to verify fuel is coming through the return line. If not, you could have a restriction in the return line or a bad fuel pressure regulator. If you haven’t done so already, change the fuel filter. For starters I recommend getting a fuel pressure test gauge to verify a pressure build-up.

A restriction could be a kinked line, a poorly flared connection, or debris in the line. A visual inspection of the lines and flares at the connection points is required. Then with the line disconnected, compressed air should verify there is not any debris in the line blocking the flow. To test the fuel pressure regulator with the fuel pressure gauge attached, disconnect the vacuum line attached to it, and the pressure should read higher or change, then reattach the vacuum line and the pressure should drop or change. If not, you have a bad regulator (that is after verifying the return lines are not restricted).

If you do not have a restriction or pressure buildup, you unfortunately may have to lower the tank to get a good visual inspection of what is actually leaking. If you want to have the fuel leak diagnosed, you can contact a professional technician, such as one available from YourMechanic who will perform the diagnostic and provide an appropriate repair solution.

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