Need help with EFI problems

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Jun 14, 2018 | 08:15 PM

baddad457

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From: south louisiana

Need help with EFI problems

Awhile back my 96 E150 started popping like mad anytime you nailed the throttle. Found several things, first was a massive vacuum leak, there's a port in between the throttle bores that transitions to a1/4" or so plastic line that goes to a manifold on the driver's side under the dash in the engine box. Next was the pass side header collector worked loose. Fixed that and decided to remove the Cat. With all that, it still pops when you put your foot into it. With the code reader hooked up the Short term fuel trims run anywhere between minus zero to 5-6. Before I fixed the above issues it would register a lean condition on bank 2. Now the only thing comes up is the cat's missing. Nothing about running lean. Can't find any more vacuum leaks spraying with carb cleaner all off the engine with it running. The only other part I'm going to replace is the pass side upstream O2 sensor. We replaced the other two. Motor has GT40 heads, Cobra rockers, shorty headers and full 3" exhaust. Also noticed this evening with it running and the cowling off is the driver's side header will glow red running in park at around 1500+ rpms. Faster you go the redder it gets. Fuel pump and regulator are new.

Jun 14, 2018 | 09:34 PM

Conanski

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From: Ottawa, Ontario

Could be a leaking injector, does it hold fuel pressure?

Jun 14, 2018 | 09:38 PM

baddad457

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From: south louisiana

Haven't checked since installing the new pump and regulator, but before then it would show about 20psi on a gauge.

Jun 15, 2018 | 02:13 AM

xlt4wd90

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From: SoCal

Isn't normal pressure 40 PSIg? I second checking for fuel pressure leak-down, and point to the injector on that cylinder whose pipe is glowing red.

Jun 15, 2018 | 08:46 AM

baddad457

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From: south louisiana

Seems like a leaking injector would make it run rich. Or is leaking, mean the injector O ring leaking ? I'm gonna pull the plugs tomorrow and see what they tell me. Any comment on the STFT numbers ? Seems they're low to me, but I don't know what normal readings should be.

Jun 15, 2018 | 08:47 AM

baddad457

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From: south louisiana

Quote:

Originally Posted by xlt4wd90

Isn't normal pressure 40 PSIg? I second checking for fuel pressure leak-down, and point to the injector on that cylinder whose pipe is glowing red.

Yea, that's what I thought. And why I replaced the pump and regulator. Figured one or both were going south.

Jun 16, 2018 | 05:44 PM

Conanski

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From: Ottawa, Ontario

If you have one dirty injector that is always bleeding fuel the computer will see that side of the engine as rich at the O2 sensor and will try to compensate by leaning out all injectors on that bank. The plugs should tell the story, if you have 1 brown/black plug and 3 that are very pale or white you found the problem.

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Jun 16, 2018 | 06:20 PM

baddad457

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From: south louisiana

Ok, got a chance to work on it again today. First off I pulled the plugs. 7 were normal colors, #5 was a little dark grey. It's not running lean. The gaps were at .050-.060 so I decided to replace them and the wires. Had just bought a new set of Ford 9mm's for the Comet so I put em to work. The cap and rotor were toast after 40K miles. Even with brass terminals, they were all black. Next off I changed the pass side upstream O2 sensor. Got everything back together and fired it up. Popping when you punch the go pedal was gone. So got that fixed. Took it down the road and pretty much ran better, with only the occasional stumbling nothing like it was before. I think maybe it needs time to adjust the fuel curve. The short term fuel trims are back to responding, they shoot up to 25-27 when you nail the pedal, where they did nothing before.