No fuel
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New User
Joined: Feb 2011
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No fuel
I have a 1986 F-150 5.0 mfi. It's in good shape for a Michigan truck of that year. I have replaced the fuel pump in the rear tank, the pump on the frame rail, the fuel filter, the fuel pressure regulator, and have done a cylinder balance test, a vacuum test (21"hg), fuel psi test 41psi, but it takes 50 to 100 key cycles to attain fuel pressure. It runs great at an idle but it stumbles, or stalls with any throttle added. I am going to check for voltage drop at the high pressure pump today. Any help would be appreciated, as I am a struggling auto motive student.
Thanks, 86F1502WD
Thanks, 86F1502WD
Post Fiend
Joined: Dec 2007
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From: Lost
You've got fuel pressure, but what about fuel volume? A restriction in the lines could allow for enough pressure and volume to run the engine at idle, but not enough for anything else. Could also explain the delayed fuel pressure reading.
The restriction could be anywhere from the screen on the bottom of the in-tank pump, somewhere in the lines, the tank selector valve, ECT.
Certainly wouldn't be the first person to deal with crudded up fuel lines in a 25 year old vehicle.....
The restriction could be anywhere from the screen on the bottom of the in-tank pump, somewhere in the lines, the tank selector valve, ECT.
Certainly wouldn't be the first person to deal with crudded up fuel lines in a 25 year old vehicle.....
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On the volume test it put out more than the repuired 1 pint in 30 seconds. I am really stumped with this one. Nothing adds up. I even blew the lines out berfore I replaced anything. Everything came out clean, inspected the sock wiped the tank, blew the lines out into a gas can and inspected the gas, this one just has me confused, at least it's mine and not a customer car. Could it be burnt contacts in the relay?
Last edited by 86F1502WD; Feb 15, 2011 at 01:58 PM. Reason: not enough details inlcuded
