4.9 intementent miss

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Dec 29, 2008 | 09:42 PM

73f-1

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From: Knoxville,TN

4.9 intementent miss

I have a 87 f-150 4.9efi 4spd no a/c. Sometimes at idle it starts missing,I can smell fuel,but does not smoke.It will buck while driving.It does it 75% of the time,sometimes it drives great to and from work without missing a lick.New plugs, fuel filter,checked and replaced all vacuum lines.It code an egr code,I put a blockoff plate between it and the intake,no change.Tested fuel pressure read 57-60,didn't drop when missing(haynes manual says up to 60 ok on all exept for 87 model,but the fuel pressure regulator part#is same for the other years).Please help,Thanks.

Dec 30, 2008 | 11:50 AM

Lazy K

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I think the first thing you should do is to go to fordfuelinjection.com and click on Fuel Pressure Regulator and read. Good luck.

Dec 30, 2008 | 12:53 PM

quicklook2

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From: Lakewood, Ohio

how old are the ignition wires?

Dec 31, 2008 | 09:20 AM

73f-1

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From: Knoxville,TN

The wires are three years old 12,000 miles

Dec 31, 2008 | 09:29 AM

73f-1

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I'm going to check the cap,button,wires,fuel pressure regulator,and coolant temp sensor.will let you know.

Dec 31, 2008 | 09:55 AM

quicklook2

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From: Lakewood, Ohio

what brand and type of plugs?

Dec 31, 2008 | 10:29 AM

wolfy

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check your distributor cap and rotor inside, a lil bit of moister will foul those up. also on my 91 4.9 I6 i simply unhooked the vacuum line to the egr valve and it stopped the bucking / hesitation during light throttle. you might want to give that a try.