help: fuel pump does not work good when engine gets HOT???

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help: fuel pump does not work good when engine gets HOT???

Postby ski.dive » Sun Nov 03, 2013 1:01 pm

My in tank fuel pump works OK for the first 20 or so minutes,[1977 stock 4cyl. VEGA] ,

but when the engine gets HOT, It pumps very little gas and the engine runs rough and stalls? :bang:

I let the motor cool off for 20 minutes it pumps Ok again???

I can tell by looking at the see-thru in line fuel filter, that Im not getting any or little gas to the carb.

Any suggestions are helpful.
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Re: help: fuel pump does not work good when engine gets HOT?

Postby hammerdown7 » Sun Nov 03, 2013 1:50 pm

How much gas do you have in the tank? The pumps should be submersed for best cooling of the pump.

Dick
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Re: help: fuel pump does not work good when engine gets HOT?

Postby vegastre » Sun Nov 03, 2013 2:00 pm

Just a guess mind you,
The in tank fuel pumps cool by gas flowing through the pump and old pumps eventually start to over heat and cause weird problems if they just don't stop completely. If the pump is new or recently replaced then I would look elsewhere.
Phil Kennedy~
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Re: help: fuel pump does not work good when engine gets HOT?

Postby cjbiagi » Sun Nov 03, 2013 5:29 pm

It could just be bad pump, is it original or has it been replaced lately? Other things to consider are poor electrical connections that can be heating up causing higher resistance and then not supplying the correct voltage to the pump. You can also have a clogged pickup sock on the end of the fuel pump. Also consider looking at the gas cap, is it correct or been replaced lately? The tank needs to vent somehow to allow air to replace the fuel being used or you will create a vacuum inside the tank. I would also look at the short rubber hoses between the tank and the metal fuel lines, if these are original they could be soft and collapsing. Have you had the tank out lately to do any work or inspect it?
Clyde.........75 Monza 2+2
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Re: help: fuel pump does not work good when engine gets HOT?

Postby Monza Harry » Sun Nov 03, 2013 11:03 pm

The above by Clyde, Phil and Dick are all great places to look and probable, you could also look at the oil pressure and oil pressure switch as well perhaps the pressure is falling off and the switch is protecting the engine like it is supposed to. Just giving you idea's to look at if these others fail. Harry
Last edited by Monza Harry on Wed Nov 06, 2013 6:42 pm, edited 2 times in total.
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Re: help: fuel pump does not work good when engine gets HOT?

Postby tonysq » Mon Nov 04, 2013 12:11 pm

Another thing to check is to make sure the fuel line is not too close to the exhaust. Kinda like vapor lock only from the pushing side...

Chris
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