i got a litlle problem

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Sep 12, 2011 | 01:23 PM

mcmavv

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Joined: Nov 2008

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From: s.ont.canada

i got a litlle problem

my 351/400 which has been runnin like a dream lately,has all of a sudden decided it wont idle.as long as i stay on the throttle it runs fine,as soon as i come to a stop,boom its stalls.pulled the fuel lines from the pump to the carb,blew out both the in carb and inline filters,no obstruction.still wont idle.any ideas where to go next will be very helpful.aint touchin it again till tomorrow.thanks in advance.

Sep 12, 2011 | 01:27 PM

Grubbworm

Cargo Master

Joined: Apr 2010

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From: Acworth, GA

Check ALL of your vacuum lines and caps. Mine has the same issue occasionally, always a cracked vacuum line or missing cap. So, I carry a box of assorted caps in the glove-box. Good luck.

Sep 12, 2011 | 01:31 PM

mcmavv

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From: s.ont.canada

caps?

u mean strib caps?

Sep 12, 2011 | 08:07 PM

fmc400

MSEE

Joined: Apr 2004

Posts: 10,386

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From: Austin, TX

Quote:

Originally Posted by mcmavv

u mean strib caps?

Huh?

I agree with Grubbworm; sounds like a vacuum leak.

Sep 13, 2011 | 01:34 PM

mcmavv

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From: s.ont.canada

checked

all the vac lines,and caps,couldnt find anything visable so i just changed them all,except the booster hose.no change still wont idle.like i said runs ,a bit lumpier than normal, as long as im pushin the pedal.foot off stalls.whats next?

Sep 13, 2011 | 02:12 PM

crazyeddie

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Joined: Dec 2008

Posts: 485

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From: Fowlerville, Michigan

Get it running and spray carb cleaner around all your vacuum hoses and fittings. If there's a vacuum leak, the carb cleaner will be drawn into the intake and you will notice a gain in RPM.

You may also want to pull your dash panel and check the climate control box - there are vacuum lines that run to the climate control to open and close heater and A/C duct doors.

Another method is to pull all the vacuum lines off the vacuum T-fitting on the intake and put vacuum caps over the fitting barbs - if it starts idling again, you have a leak in the system somewhere. You can then start re-hooking vacuum lines and trace which one is leaking.

What carb are you running? A blown power-valve in a Holley could cause a poor idle as well.

Sep 13, 2011 | 02:13 PM

crazyeddie

Senior User

Joined: Dec 2008

Posts: 485

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From: Fowlerville, Michigan

Don't forget to spray carb-cleaner around your intake manifold where it seats to the heads - you may have a leaking intake gasket (BIG vacuum leak)...