help 351m

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Jul 22, 2007 | 05:07 PM

biketruck

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help 351m

I started work on 1978 F-150 Ranger with 351m/400...91,000 miles. See post in 335 series engine section.

I can't seem to get truck to idle after my sons and I started working on it. Ran OK until I changed most all fluids, and cleaned carb. Idles for 5 seconds and cuts out only to restart then repeat.

ideas? suggestions?

Jul 22, 2007 | 11:32 PM

LxMan1

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From: Louisville,Ky.

Sounds like you have a vacuum leak somewhere.

Jul 23, 2007 | 04:02 PM

Scrapiron66

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I experienced the same situation after installing a new intake and carb. As LxMan suggests, it was a vacuum leak. Runs great now....

Jul 25, 2007 | 09:15 AM

biketruck

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I tried the trick I read about here to determine if there is a vacum leak. Sealing off air to carb should make rpm increase. This only kills engine. Vacum lines look good but I am still checking in and under moter for bad ones.

Also float looks good. Wow, this is tough...any ideas?

Jul 25, 2007 | 11:38 AM

LxMan1

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From: Louisville,Ky.

Spray carb cleaner down both sides of the intake where it meets the head and see if it idles up. If so , the intake gaskets are leaking. Also spray aroung the bottom of the carb to see if you have a leak there. It will still die if you smother the carb unless you have a really big leak. You can slowly cover it and see if the idle goes up any before choking out.

Last edited by LxMan1; Jul 26, 2007 at 05:49 AM. Reason: spillin

Jul 25, 2007 | 06:04 PM

Torque1st

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I like to use a propane torch without a flame instead of carb cleaner. I have used many flammable substances in the past.

Aug 12, 2007 | 03:40 PM

clunker86

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i had that problem before but it wasnt from cleaning the carb it was a bad carb. to keep it running you had to kep giving it gas or it would die. maybe its time to rebuild carb or new one. i had a 2bbl so i replaced the carb and intake for a 4bbl.