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Old 08-24-2010, 12:09 AM
mescalito's Avatar
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Default 1976 Sierra, fuel delivery issues

I suppose I'll start at the beginning. The truck has been sitting for a couple of years with little attention. I recently rebuilt the carburetor and noticed the float bowl was bone dry, so I assumed the fuel pump had gone out and replaced that after I finished the overhaul. After priming the carb a few times with a small amount of fuel, it would start for a few tantalizing moments before cutting out. I detached the after-pump fuel line and situated a catch container underneath it and started it a few more times via the priming method and still nothing, although the pump seemed to be trying to do its job.

I'm not sure if this is related, but the fuel gauge is screwed up in such a way that when the tank is empty, it reads at a quarter full. So as you add fuel it always displays a quarter tank more than is actually in the tank. I haven't taken it off to inspect it yet, though I presume that the sending unit is at issue.

thanks in advance for any input
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Old 08-24-2010, 12:57 AM
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Hmmm think maybe the fuel line from the tank is clogged. Try the reverse of what you did. Use a 1 gallon tank of gas and see if the pump pulls fuel from that when cranking.
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Old 08-24-2010, 11:22 PM
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Quote:
Originally Posted by mescalito View Post
I suppose I'll start at the beginning. The truck has been sitting for a couple of years with little attention. I recently rebuilt the carburetor and noticed the float bowl was bone dry, so I assumed the fuel pump had gone out and replaced that after I finished the overhaul. After priming the carb a few times with a small amount of fuel, it would start for a few tantalizing moments before cutting out. I detached the after-pump fuel line and situated a catch container underneath it and started it a few more times via the priming method and still nothing, although the pump seemed to be trying to do its job.

I'm not sure if this is related, but the fuel gauge is screwed up in such a way that when the tank is empty, it reads at a quarter full. So as you add fuel it always displays a quarter tank more than is actually in the tank. I haven't taken it off to inspect it yet, though I presume that the sending unit is at issue.

thanks in advance for any input

WOW!!!! havent had my hands on one of those motors in awhile.......the fuel gauge problem is probably the gauge its self they were known for doing that very thing....as far as fuel delivery.....I say pull the tank and check it out the sock filter could have a bunch of rust built up on it....while you have the tank down diconect the fuel inlet to the pump and the outlet from the tank and blow some air through it with an air compressor (not real high pressure....20psi should do) it could also be the pick up is clogged to......on a side note did you get the pump seated right on the crank? that was another common mistake.......just some ideas
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Old 08-25-2010, 07:05 PM
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At ruffneck4lyfe's suggestion I ran some tubing from the tank-side of the pump into a gallon gas tank, and it pumped just fine so I think I can rule that out. I haven't dropped the fuel tank yet, but that is my next little project. Most of the steel line between the tank and the pump looks good, but some of the short rubber segments appear due to be replaced.

I appreciate the ideas.
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Old 08-25-2010, 07:05 PM
 
 
 
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1976, 76, bowl, carburetor, chevy, delivery, float, ford, fuel, gas, gauge, gmc, jumps, lines, problems, sierra, truck

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