Skip the auto shop - Our mechanics make house calls

Q: fuel pressure leak?

asked by on

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.

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.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: High RPM but Slow acceleration

Hi Giovanni, Thank you for contacting us. We understand that you think it's the CAT. However, form our end we cannot state that with 100% certainty. Is it possible that a clogged up CAT is the source of the high...

Q: Information on replacement parts

Hi, thanks for writing in. There are a vast variety of companies out on the market that make aftermarket brake pads and wheel bearings for nearly every car on the market including your Jeep. Just be sure to identify the...

Q: I replaced my oil sending unit and it screwed I further than the old one kinda thinking i screwed up

The oil sending unit has threads that are tapered and the new sensor may have less of a taper than the old one, causing it to screw in farther. Be sure that you don't over tighten the sensor. You should...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...
How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...