Fuel problem

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Bigrigpapa

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1982
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I've got an 82 K10 with a 350. It runs fine but when I get in to start it, I've got to pump the crap out of the pedal for it to start. I noticed that the visible fuel filter by the Holley carb doesn't have any gas in it. I know it's supposed to always have fuel in it so my question is, after I shut it off where the heck is the fuel going ? Once it's running, everything is fine. Thanks for any help given
 

chengny

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I am assuming that you are running the stock mechanical fuel pump - correct?

If so, the pump is bad.

There are a pair of spring loaded check valves in these pumps that prohibit back flow both while in operation and also when idle. If they are leaking (or the springs are weak) the pump does not function as designed. You might get less than normal fuel flow when running or - when the engine is off - gas can flow by gravity out of the carburetor and back into the tank.
 

Bigrigpapa

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The pump looks new but I'm not sure because we've just recently bought this truck. I wonder if I should replace it or look into swapping it for an electric pump? Thank you for the guidance though.
 

PrairieDrifter

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You can get a lot of life out of a mechanical pump. But if you want to convert to an electric fuel pump you could do it, it will just be a little bit more expensive because you'll need a pressure regulator too
 

chengny

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If you had a Q-jet installed, I would suggest checking for leakage at the float bowl bottom plugs - but because you have a Holley, that doesn't apply.

If it's not going down into the manifold, the lost fuel must be going back into the tank.

Try this:

Someday, after you have parked the truck for the night, restrict the flow of fuel within the gas line. Take a pair of needle nose vice-grips and gently pinch down on the rubber section of hose that connects the steel tubing to the gas pump:


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The next morning, release the vice-grips and try to start the truck. If it starts right up...you will have confirmed backflow through the pump.
 

HotRodPC

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Yep, sounds like a combo of problems to me. #1, check valve in the fuel pump is bad and allowing the fuel to drain back to the tank when the fuel pump is not being ran by the engine, and #2, the well plugs in the carb are allowing the fuel to drip out of the float bowls into the intake. So then you have to crank the hell out of it #1 to get fuel pumping again and #2 to fill the float bowls before the accelerator pump has something to pick up on. Fix them well plugs in the carb, and that fuel pump will probably work just fine because if your float bowls keep fuel, before they even close to empty, the fuel pump would have caught up.
 

MadOgre

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What about fuel line being too close to exhaust causing hot fuel?

Is it hard to start when its cold or when its hot?
 

PrairieDrifter

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If you weren't losing gas through your fuel pump which you may not be, and it is going into the intake it would probably flood the motor and of course would cause extended cranking due to it being flooded. But it depends on how fast it leaks down, if it sits overnight or for a long period that fuel will just evaporate and you can't tell if your losing gas into the intake.

If you can drive it and get it warmed up and shut it off and if it doesn't take very long to leak all of the gas you can try starting it right away after the gas leaks down you can flatfoot your pedal and see if it starts right up, that way you can tell if it's leaking into the intake
 

HotRodPC

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My C20 has these same problems. If I shut it down one afternoon, and need it the next morning, it's not so bad, but if I let it sit for 2 days, I have to crank the hell out of it to get it to start, so I'm positive my well plugs are leaking down and probably the fuel pump check valve too.
 

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