Fuel Pump Testing for Cold Starting Problem

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Jan 30, 2007 | 10:56 AM

tractoman

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Joined: Feb 2006

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From: Sonoma, CA

Fuel Pump Testing for Cold Starting Problem

I am suspicious of my fuel pump leaking back through its diapragm when it sits for a couple days. It's difficult to start lately if I haven't run the truck for awhile. How long should it hold fuel pressure? This is a '76 460 with Carter AFB and 1" Transdapt squarebore to Ford spreadbore adapter and 1" 4 hole spacer. Once it's running, it's fine and it will start quicker in the morning after using it the day before than if it sits for a week. I've checked the choke and fast idle adjustments and it all seems correct. Over the summer I could step down once to activate the choke and fast idle and it would fire right up. Now I do this dance a few times and I have to pump the pedal a few times between starting attempts before it lights up. It'll also fire up right now if I prime the carb but that is a hassle. Carb was rebuilt less than a year ago.

Last edited by tractoman; Jan 30, 2007 at 10:58 AM.

Jan 30, 2007 | 01:52 PM

Mil1ion

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Joined: Jan 2008

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I have the same problem.

What I do now is pour a few ounces of gas down the carb and it starts on the first kick.

The problem isn't the fuel pump.

IMO, The problem is evaporation.

Jan 30, 2007 | 03:03 PM

tractoman

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From: Sonoma, CA

What causes the evaporation? I would guess it would evaporate in the hot weather more than the cold or is it the hot engine causing it. Can it be corrected?

Jan 30, 2007 | 04:05 PM

beartracks

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From: Albuquerque

It's not the pump. If there is no gas in the carb to start with it either evaporated of leaked out. It cannot leak back through the pump.

Jan 30, 2007 | 04:07 PM

samickguy15

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Joined: Feb 2004

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From: Delavan, IL

A hot engine will cause evaporation year round. Not very likely if it's 6° outside, but if it's 40/50° it's totally possible. Try either re-routing or putting some insulation on your fuel line.