lean/ fuel pressure problems?
New User
Joined: Feb 2002
Posts: 9
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From: western
lean/ fuel pressure problems?
hi guy's. i'm troubleshooting a lean (code 41) condition. fuel filter was replaced a few days ago. today i hook up a fuel pressure tester to the schrader valve on the fuel rail. with the key on/engine off i get 38psi. and it holds that pressure. start the engine and pressure drops to 34psi and holds steady. goose the throttle to the floor and psi jumps to 44psi, release throttle and pressure drops back to 34psi. with engine idling, remove vacuum line from fpr and pressure goes back up to 44psi. no sign of fuel leaks at fpr.
question: are these fuel pressure numbers within spec? thanks for your help :-)
ric
91 F250s/c w/7.5L EFI
question: are these fuel pressure numbers within spec? thanks for your help :-)
ric
91 F250s/c w/7.5L EFI
Postmaster
Joined: Jul 1999
Posts: 3,172
Likes: 4
lean/ fuel pressure problems?
Code 41 covers a lot of ground . If the response fron the O2 Sensor is within specs then check for vacuum leaks . I found a rusted Vacumm Resevior Canister to be the cause of the Code 41 I chased for an hr a few days ago . The canister leak was along the bottom , very hard to see or hear . Check all the vacuum lines , pay attention to any of those plastic elbows & connecters .
New User
Joined: Feb 2002
Posts: 9
Likes: 0
From: western
lean/ fuel pressure problems?
paul, you're right on the code 41. there are many things that can cause it. the vacuum lines are next on my search. the O2 sensor is very new and i've also checked for exhaust leaks upstream of the sensor. if it's any help, when i cold start the motor it doesn't have a fast idle function. meaning, it idles very low when cold and misses and blows black smoke till it warms up. still, 41 is the only code.
thanks again for your guidance :-)
ric/scratching his head
91 f250s/c w/7.5L,banks power pak
thanks again for your guidance :-)
ric/scratching his head
91 f250s/c w/7.5L,banks power pak
Postmaster
Joined: Jul 1999
Posts: 3,172
Likes: 4
lean/ fuel pressure problems?
Even though the fuel psi seems to hold , with the black smoke at cold startup thats a pretty sure sign that the engine is getting too much fuel , at least on a cold start . You may have an injector(s) leaking. What you might try is when the engine is cold is turn the key to run to pressurize the fuel system , shut the key off & watch how the pressure bleeds off . Sometimes temperature can have an effect on if & when an injector leaks . Also make sure the throttle body & air bypass valve are clean just to rule those things out as part of the low idle speed .
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