High fuel pressure problem?
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Joined: May 2006
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High fuel pressure problem?
Well here's my 1st post. My 93 f150 5.0L has been running rich and I can't seem to fix the problem. I ran a self test which came back all ok. I checked the fuel pressure and it was 40 psi with key on engine off, but jumped to 70 psi with the engine running. I then changed the FPR and the same thing is still happening. Could the injectors be hanging up resulting too much pressure build up? What else is there to check?
Any help is much appreciated.
Thanks
Any help is much appreciated.
Thanks
Logistics Pro
Joined: Mar 2005
Posts: 4,698
Likes: 47
From: Mexico, Missouri
Could be the pump itself going bad. Injectors usually leak down. You can disconnect the return fuel line from the fuel rail and insure there is no obstruction. Also if you have a container, you can disconnect the fuel line from the fuel filter and direct it into the container. Turn the key into the (ON) position and see if the flow is within specs.
It really sounds like you have an obstruction in the return line from the fuel rail, but without further diagnosis, it's hard to tell. If the pump is OEM, it could simply be age is a factor, it's over pressuring the system and it's going bad.
Might do a search here on high fuel pressure and see what else may be the culprit. Let us know what you find out.
It really sounds like you have an obstruction in the return line from the fuel rail, but without further diagnosis, it's hard to tell. If the pump is OEM, it could simply be age is a factor, it's over pressuring the system and it's going bad.
Might do a search here on high fuel pressure and see what else may be the culprit. Let us know what you find out.
FTE Legend
Joined: Jun 2006
Posts: 31,930
Likes: 1,499
From: Ottawa, Ontario
No the injectors won't affect fuel pressure unless one of more is stuck open and then you would have a low pressure problem. You either have a restricted return line or a partially clogged check valve in the fuel delivery module inside the tank. Does the truck have dual tanks? If so does it do the same on both?
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Thanks for the responses. I'll check the return line flow next. I only have a single rear tank. The fuel pump is the 2nd one in the truck with 351K miles on the clock so I am probably due for another pump...
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