302 EFI stumbles and

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Apr 27, 2003 | 07:34 AM

oldford2

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302 EFI stumbles and

My prob here is a with a 302 EFI in a 1986 250
When i give it gas say 1/2 pedal it will stumble and act like it is going to die if i dont get off the gas pedal. Starts up smooth and runs great until i give it 1/2 throttle or more under load. What should i be looking to check out ?
thx

Apr 27, 2003 | 01:45 PM

steve83

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Joined: Nov 2002

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From: Memphis, TN

302 EFI stumbles and

Ignition timing, valve timing, vacuum leaks, TPS, MAP, & SPOUT. Have you pulled the codes?

Apr 27, 2003 | 04:39 PM

oldford2

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302 EFI stumbles and

yes the codes have been pulled as code 31---egr and sensor and still the same problemo. after replacement

Apr 27, 2003 | 04:41 PM

444stroker

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302 EFI stumbles and

does it puff any blue smoke? if it does i'd yank the #8 plug and injector and have a look-see

Apr 27, 2003 | 04:54 PM

Franklin2

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Joined: Jan 2001

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From: Virginia

302 EFI stumbles and

oldford2 has had this problem for awhile, and is looking for some fresh ideas. But here is some valuable history on the problem(2 pages)

https://www.ford-trucks.com/forums/s...hreadid=111632

Apr 27, 2003 | 05:10 PM

oldford2

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302 EFI stumbles and

Quote:

Originally posted by 444stroker
does it puff any blue smoke? if it does i'd yank the #8 plug and injector and have a look-see

No puffs of blue smoke whatso ever !

Thx so much Franklin2 for fowarding folks to my problem in the past!
Hopefully some one will come up with the fix !

Apr 28, 2003 | 04:38 AM

444stroker

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302 EFI stumbles and

what kind of fuel pressure are you getting? possibly a fuel pressure regulator? have you tried running injector cleaner through? i like the berryman's b12 chemtool stuff, it's the most potent i've come across. is the fuel filter good? have you checked ignition timing? sounds like a fuel system issue to me but it's always good to cover all the bases.

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May 6, 2003 | 12:17 PM

f100beatertruck

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Joined: Apr 2003

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From: Parkesburg PA

302 EFI stumbles and

I had the same code on my Bronco (302 EFI), but it didn't have a stumble, just high idle. It turned out to be the plenum gasket between the base manifold and the upper. A vacuum leak could cause a lean stumble. The gaskets sometimes creep out with age.

If you can't find a vacuum leak, I would get someone to test the fuel pressure under load. The pump could be weak, or the line/filter blocked.

If the fuel pressure checks out, look at the ignition. The coil could be worn out and not giving a hot enough spark. What are your plugs gapped at? You could try closing them up .005" and see if you get an improvement.

Lastly, the injectors could be clogged and not spraying right.

David -= 83 F100 - 300 4spd 4x2 =-

P.S. I read in your other thread about the TPS, and someone said .8v at idle, I would set it to .99v. This will give you a slightly better off idle response. I don't think this will fix your problem, but once it's fixed it will give you a crisper throttle response.