Injector trouble or something else?
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Joined: Jan 2010
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Injector trouble or something else?
I posted some info on my 92 f150, 5.0 a month or so ago.When checking the fuel pressure with the key on,the pressure goes to 40 psi,but when the pump disengages it immediately falls to zero(in 2 seconds or so).I also have some drivability issues and rough idle at times,along with a strong gas smell at idle..Exhaust pipe tips are black as coal..It has been said that the injectors leaking could cause, or is the problem..Does anyone else know of any other condition that could cause this problem???One last note,the engine usually has to be cranked over several times before it will start,and if you get on it ,for example passing a car,it will backfire....I appreciate any help i can get.....
Lead Driver
Joined: Nov 2002
Posts: 9,557
Likes: 44
From: Concord, NC
Have you checked the fuel pressure regulator for a ruptured diaphragm? Pull the vacuum hose and if there is fuel in the vacuum line, it is time for a new pressure regulator, even though it still maintains the correct static fuel pressure.
Lead Driver
Joined: Nov 2002
Posts: 9,557
Likes: 44
From: Concord, NC
It could be the fuel pump, or it could be a stuck-open injector, or it could be the fuel pressure regulator (which you have already replaced). Have you taken any of the plugs out to see what they look like? If one is more carboned up than the rest, there may be a problem with that one cylinder, either injector or something else. The fuel pump has a check valve inside it to both prevent fuel from going from the running pump backwards into the inactive tank and also to maintain fuel pressure after shut down.
I think I would track down the fuel pressure problem first, then the rich running condition may solve itself. That could save you from spending money to replace various sensors that may still be working properly.
I think I would track down the fuel pressure problem first, then the rich running condition may solve itself. That could save you from spending money to replace various sensors that may still be working properly.
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Posting Guru
Joined: Dec 2008
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From: Rusty, Maine
^ I agree. You need to find out where your loosing your residule fuel pressure. I would start at the pump in the front tank. It sounds like the check valve in that pump may be bad.
These dual tanks can be a blessing and a curse.
These dual tanks can be a blessing and a curse.
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Lead Driver
Joined: Nov 2002
Posts: 9,557
Likes: 44
From: Concord, NC
Do you have any codes coming up in the computer? If all the plugs look the same, I would think that it's not the injectors. And you've double checked that there's no fuel in the fuel pressure regulator vacuum line?
