1989 460 EFI problem

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Mar 20, 2020 | 10:12 AM

Lisa Bitzer

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1989 460 EFI problem

Truck starts and runs great. 4 and 5 gear no power and sounds and feels like it is running on 6 cylinders????

Mar 20, 2020 | 10:58 AM

timbersteel

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From: Mexico, Missouri

Could be anything.

Have you done anything to it recently? Any parts swapped, replaced, or repaired?
Have you checked for codes?
Have you checked fuel psi?

Let us know what you have checked or haven't and we can go from there.

Mar 20, 2020 | 12:21 PM

UNTAMND

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From: Lansdale, PA

First thing you should do is check for codes. And then the next thing you should do is put a fuel pressure gauge on and verify that you are getting at least 38 psi while accelerating, and at idle it should be no less than low 30s. If you remove the vacuum line from the regulator at idle, you should have 38 to 42 psi

if you do not have that much fuel pressure then your pump or regulator are bad or possibly fuel filter is plugged

Mar 20, 2020 | 12:31 PM

Lisa Bitzer

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I do have a fuel pressure problem. At idle 40 psi .accelerating it drops almost to 0. New fpr, hpfp,fuel filter. No kinked fuel lines. Good flow in return line

Mar 20, 2020 | 12:36 PM

timbersteel

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Did you replace the low psi in-tank pump? Your truck requires both to be working correctly or you will have issues.

Do you have dual tanks?

Mar 20, 2020 | 01:24 PM

Lisa Bitzer

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Not yet. I am replacing both tanks and lpps, fuel lines,crossover. Right now its running off a tank out of a 1998 f150 with the pump that was in it. Its holding 35 psi. Could not check it in acceleration. Now that I think about it I may have a volume problem with this setup. What I don't understand is why this is happening only in the higher gears.