Home » Public Forums » GMCnet » Fuel pump in but no pumpy
| [GMCnet] Re: Fuel pump in but no pumpy [message #362881 is a reply to message #362880] |
Tue, 16 March 2021 22:38   |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma:
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Senior Member |
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Keep in mind that a Vain driven pump need a filter to maintain long life,
Several of our customers have with out these pumps by not having a filter.
Go to our sight and see how we do it to avoid vapor loc by mounting them
outside the frame and close to the tanks.
On Tue, Mar 16, 2021 at 8:19 PM Richard H Staples
wrote:
> Duce,
> Since it worked before, and the only thing changed was the fuel pump, I'd
> start there. I'd disconnect the fuel line from the pump (suction side),
> attach a vacuum gauge, and crank the engine with the starter for ~30
> seconds or so. The gauge should read at least 5 or 10 inches of vacuum, and
> should hold that reading for at least a minute or so. If it does not, I'd
> pull the pump off and recheck it.
>
> Work the lever by hand and make sure it pulls vacuum. If it does not,
> you've got a defective pump. It happens!
>
> If the pump works manually, look for scratches on the side of the lever.
> It is sometimes possible to install the pump a little cockeyed, so the lever
> essentially "misses" the cam in the engine, then no pump action.
> Reinstall carefully.
>
> If the pump DOES pull vacuum when the engine cranks over, I would check
> carefully for any small leaks in the fuel lines from tanks(s) to pump. Any
> small leak in those lines will allow air to enter instead of fuel. (Been
> there, done that, although not on the GMC.) If you have access to a
> "Mity-Vac" or similar vacuum pump and reservoir, attach it to the fuel
> line and make sure you can draw fuel from the tank.
>
> All the suggestions about electric pumps are generally good ones. I have
> a Carter 4070 pump in my auxiliary fuel feed, with a primer switch on the
> dash. It does help to overcome vapor lock on occasion. OTOH, the
> original mechanical pump is simple, safe, good enough for GM, and worked
> for 45
> years. It should work now.
>
> My 2ยข, HTH
> Rick Staples
>
> --
> Rick Staples, '75 Eleganza, Johnstown, CO
>
> "Advice is a dangerous gift, even from the Wise to the Wise, and all paths
> may run ill." -Tolkien
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--
Jim Kanomata
Applied/GMC, Newark,CA
jimk@appliedairfilters.com
http://www.gmcrvparts.com
1-800-752-7502
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Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
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