Ruby doesn't want to idle

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Feb 8, 2012 | 11:19 AM

bighatchy

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Ruby doesn't want to idle

So Ruby has decided the she doesn't want to idle very good. 73 f100 lwb 390 auto 2wd edelbrock 1406 duraspark II. The engine seems to run as usual when your driving, but if you have to stop the engine might slow to a stop. It seems to be carb/fuel related. I turned the idle up a hair but it didn't cure the problem. I changed the fuel filter as well. Do I need to tear apart the carb? Thanks in advance guys! Daryl

Feb 8, 2012 | 11:45 AM

earthquake68

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From: THIS IS SPARTA!, ...Mo.

Plug in a fuel pressure gauge after the fuel pump. If you hold 5 psi, rebuild the carburetor.

Feb 8, 2012 | 08:29 PM

fmc400

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Usually fuel issues manifest themselves in the opposite way; it will idle fine (when fuel demand is low) but cut out as RPMs increase and the demand for fuel increases. Check for vacuum leaks; vacuum leaks typically show up at idle but go away as the throttle is opened (and vacuum drops naturally).

If there are no vacuum leaks, check the idle mixture using a vacuum gauge.

Feb 8, 2012 | 09:07 PM

earthquake68

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From: THIS IS SPARTA!, ...Mo.

Agreed, but a vacuum leak usually raises the idle, not chokes it out. My thought was needle and seat not sealing (still closing, but not sealing properly and allowing gas to seep through) and flooding the engine at idle. When there's more demand for fuel, it uses it instead of drowning it.

Feb 8, 2012 | 09:08 PM

Blue and White

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Quote:

Originally Posted by earthquake68

Plug in a fuel pressure gauge after the fuel pump. If you hold 5 psi, rebuild the carburetor.

Besides this, I have found a can of Gumout (carb formula) can help. My dent has done this... the gumout seems to help clear it up. I know I eventually need to replace or re-build the carb but not ready yet.

Feb 8, 2012 | 09:13 PM

bighatchy

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I bought the carb on craigslist a few months ago and I at the time just put it on to see if the engine would run. It had been sitting since 2000. It wouldn't surprise me if there is dirt or something stuck somewhere

Feb 8, 2012 | 09:38 PM

Blue and White

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PS... I understand the Edelbrock carb needs the fuel pressure regulated to 4-5 PSI. The standard 6-8 PSI from a mechanical fuel pump is too much for the Edelbrock needle/seat setup. The Holly regulator (Summit or speedshop) is supposed to be best. This could be the problem... and needs to be checked/corrected anyhow if you stay with an Edelbrock carb.