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Ron, ASE Certified Technician
Category: Ford
Satisfied Customers: 34184
Experience:  23 years with Ford specializing in drivability and electrical and AC. Ford certs and ASE Certs
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The front fuel tank is overfilling. We replaced the fuel

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The front fuel tank is overfilling. We replaced the fuel pump in the front tank, and it is still overfilling
JA: Have you ever replaced the fuel pump, or is this the original?
Customer: Not sure if it was the original, but we just replaced it yesterday.
JA: What is the model/year of your Ford?
Customer: 1995 Ford F150 with a 5.8L engine
JA: Are you fixing your F150 yourself? What have you tried so far?
Customer: No, we are a repair shop, looking for advise
JA: Anything else you want the mechanic to know before I connect you?
Customer: Not at this time

Hello. My name is ***** ***** I am happy to assist you today. Give me just a moment to review your post, and I'll be right back with the help you need.


Did you replace the complete assembly?

Customer: replied 3 months ago.

The common cause for this type of problem is in most cases a failing check valve in the pump. Each fuel pump contains a check valve on its high pressure supply outlet port and a shuttle valve on its return inlet port. When the front pump is not running, the shuttle valve and check valves are designed such that they should block flow of fuel into the front fuel tank. When the front pump is running, the shuttle valve opens and allows fuel to flow into the tank.
The function of the rear in-tank fuel pump is identical to the front in-tank pump. In order to determine if you have a defective fuel pump your going to need to do a little testing. See the steps to do this in the link below.

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