fuel problems please help
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New User
Joined: Feb 2011
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fuel problems please help
I am having fuel issues after replacing my high flow fp. I have a 1989 F150 300 cc 4 speed 4x4 had a problem out on the road where it was running just fine and stalled checked the usal no problems than pulled fuel line and got no fuel when cranking so replaced fuel pump still didnt work checked eec and fuel relay then inertia switch found that it had been bypassed by a jumper wire and when i messed with it the new fuel pump started working again but now i can hear the pump doing what it supose to and the truck will only run for a second than stall will replacing the inertia switch fix this problem(it was running for over a year before) or do i need to look down another line? please help
Posting Guru
Joined: Dec 2009
Posts: 1,053
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From: Calverton
You need a fuel pressure gauge to make sure that there is enough pressure at the fuel rail, should be 50-60psi with key on, engine off. If you had 30-35psi, that may not be enough to start her. Could be the fuel pressure regulator being bad, fuel filter as another option for you. You could also borrow a gauge from AutoZone to see what you got for pressure...you should also run a self test to see if any stored fault codes are available, they may point you in a different direction. Heres a cool site from someone here
How to Solve an EFI No Start
How to Solve an EFI No Start
Fleet Mechanic
Joined: Aug 2005
Posts: 1,462
Likes: 74
From: Hartford, AL
I'm not sure about the 50-60psi. The '89's may be different and the 300 ci's may be different , but my '95 5.0 is was factory set at 39.5 psi vacuum removed from FPR, vacuum attached to FPR and at idle it is around 33-35 psi. Fuel pressure should increase closer to the 39.5 psi at WOT.
I would look at replacing the switch....seems suspect when the word "jump wire" is mentioned.
I would look at replacing the switch....seems suspect when the word "jump wire" is mentioned.
Elder User
Joined: Feb 2006
Posts: 537
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From: Formerly Nawlins
The 4.9 litre is in the 60PSI range ... the V8's are lower. My notes on mine are about 56PSI from rear and 33PSI from front for mine, that is why mine will not start on the front tank, but it will run, I don't though ... not enough fuel will grenade the engine same as too much RPM.
