Fuel Pressure
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Fuel Pressure
So I am having a fuel pressure issue now. Not sure how big of an issue it is though. Any suggestion or advice would be great. Ok, so at idle in park i am reading about 48 psi of fuel pressure on the rail. If i put the car in drive the fuel pressure doesnt change. Also if i keep it in park or gear and step on the pedal the pressure doesnt change. The gauge works i checked it on another car right after. Im thinking bad regulater or possible kink in the return line? Just want a second opinion.
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New User
Joined: Jul 2010
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fuel pressure
damn sorry cant believe i forgot to put that in. Im driving and 87 f150 with the 4.9 inline 6. My chiltons manual says i should have 30 psi in park at an idle and 40 in gear. Thats where im getting the idea of it being to high. Thing is when i brought it into the shop they said it was a bit low on pressure to. Is it possilble the chiltons is wrong?
FTE Legend
Joined: Jun 2006
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From: Ottawa, Ontario
35-40 psi is the right range for the V8's but the 300 should make 45-50psi. And the pressure should change with manifold vacuum too, so it should be at the low end of the scale at idle and increase to the high end when the throttle is opened or the vacuum line is removed from the FPR.
Fleet Owner
Joined: Aug 2005
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From: Easton,Ks
I book calls for 45 PSI at idle and 60 PSI with the vacuum hose off the FPR but I have heard 55 PSI also for WOT.
I think Paul O meant 45-60 not 45-50.
Pull the hose off the FPR and turn the key on and off with a cold engine and see if any fuel comes out of the nipple, if it does it is bad. But would not think it to be bad at 48 PSI.
If you had 60 PSI all the time then I would say bad FPR with a ruptured diaphragm.
I think Paul O meant 45-60 not 45-50.
Pull the hose off the FPR and turn the key on and off with a cold engine and see if any fuel comes out of the nipple, if it does it is bad. But would not think it to be bad at 48 PSI.
If you had 60 PSI all the time then I would say bad FPR with a ruptured diaphragm.
