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James, Ford Technician
Category: Ford
Satisfied Customers: 3632
Experience:  Ford Senior Master Tech, Ford gas and diesel expert, ASE Certified
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I have a 1986 f150 lariat with a V8 302. When I run truck

Customer Question

I have a 1986 f150 lariat with a V8 302. When I run truck for 30 minutes then park it to run in the store it sputters, stalls, knocks and pings. I have to let it cool at least 30 minutes then it runs fine on highway. In slow stop/start traffic it does it again and I lose power and can barely go 25mph. If I stay at highway speeds it will be ok. What is the problem ya think?
Submitted: 2 years ago.
Category: Ford
Expert:  James replied 2 years ago.

Hello, I think you may have a fuel pump that is failing if this vehicle is fuel injected. This is where you want to perform a fuel pressure and flow test. It sounds like the fuel pump is heating up and loses pressure at slow speeds.