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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: VeeTwin60 on April 27, 2008, 02:38:40 pm
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Hey Guys - The other day, my truck started stuttering as if it were out of gas. It is very intermittent, as it will go back to normal just a little bit later. When it is stuttering, if you push the accelerator it will cough and act like it would if it had too big of a carburetor. When it is normal, it works just fine.
Could this be a blockage in the fuel filter? Could it be a fuel pump going out? Any other ideas?
350 cu.in. w/Holley 600 CFM 4bbl Street 1850C
Thanks!
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Holley,
Power valve is my guess.
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Sure could be a power valve. Always start checking with the easy stuff. Air filter. vacuum lines. fuel filter. plugs. Look inside of the distrib. cap and see if it's cracked.
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are you using E10?
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Not knowingly. Would it be labeled on the pump?
I think I'm going to rebuild the carb and replace the plugs and wires - It won't hurt, I know they both need it.
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Replace the plugs and plug wires first and see if that helps.
E10 is usually found on the pump, it would say, "Contains Ethanol" or "Contains upto 10% Ethanol".
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Okay - I've replaced the plugs and wires (which it needed). I've rebuilt the Holley. After reinstalling the carburetor, I turned the truck over. Now, I know the bowls are empty, so it will take a few tries to fill them up and fire it off. However, it never fired. So, I disconnected the fuel line and diverted it into a container. I then turned the truck over - nothing came out of the hose ???
So, I go back to the fuel pump question - is it possible for a fuel pump to operate intermittently?
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Is your pump mechanical, or has it been changed to electrical? My guess is that the mechanical one works or doesn't. An electrical one could be intermittent.
How about a suction leak? Could the fuel pump be sucking air through a cracked/rusted/loose line?
Could the pickup tube in the tank be broken?
How about a blockage in the lines?
If you have access to a HAND OPERATED vacuum pump, or brake bleeding pump, you could try to draw a vacuum on the line to check for a leak or blockage. If the gauge won't come up off 0, it is probably a leak. If it goes up and up as you pump, and holds but you get no gas - blockage. If it goes up, but slowly falls as gas is drawn to it, fuel pump is not working.
I stressed hand operated because of the dangers of mixing electricity and gasoline.
Hope this helps... good luck!
I
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It is mechanical - and I had the same thought as you... a mechanical one works, or it doesn't - no in between.
But... it was the fuel pump. :-\ I changed it and it runs like new again. :)
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Good job!