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Fuel delivery issue please help

tnewman021

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tnewman021 Enthusiast

tnewman021

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I have a 1984 GMC Sierra heavy half ton 5.7 L V8 I replace the mechanical fuel pump and replace the coil pack yesterday I took the fuel line off from the carburetor and tried to start the truck and no fuel come out it has dual 25 gallon tanks where do I start and how do I know what is wrong

 

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txab Senior Enthusiast

txab

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Did you install the FP correctly? You need to make sure you get the pump arm under the push rod that runs off the cam

garagerog Enthusiast

garagerog

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All good ideas above, the only other thing I can think of is to ask the OP is to use the dash switch to go back and forth between the saddle tanks ( btw, I believe they're 20 gal) and make sure the fuel gauge moves. There is a solenoid that controls a valve that determines which saddle tank is being drawn from. Unlikely, but I suppose it's possible that the valve could get stuck in such a position where it isn't drawing gas from either tank.

tnewman021 Enthusiast

tnewman021

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Yes I have checked my tanks they are on 3/4 and the other one is on a quarter tank and they do move I can't find a fuel filter anywhere I think whoever had the truck before me just bypassed it I've checked the wheel wells on top of the fuel tanks and close to the engine can't find nothing the fuel pump is hooked up correctly I had to hold it with a hacksaw to have the pushrod hit the metal to make sure it was working correctly. I have check all the fuses and they are lighting up fine with my tester but I can't find why the fuel is not pumping through

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garagerog Enthusiast

garagerog

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4 minutes ago, tnewman021 said:

Yes I have checked my tanks they are on 3/4 and the other one is on a quarter tank and they do move I can't find a fuel filter anywhere I think whoever had the truck before me just bypassed it I've checked the wheel wells on top of the fuel tanks and close to the engine can't find nothing the fuel pump is hooked up correctly I had to hold it with a hacksaw to have the pushrod hit the metal to make sure it was working correctly. I have check all the fuses and they are lighting up fine with my tester but I can't find why the fuel is not pumping through

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If you have the stock style quadrajet carb, there is a fuel filter in the base of the carb where the fuel line goes in, you'll need to use two wrenches to remove the line without twisting it, and I see River just beat me to it, ha.

riverbanks Senior Enthusiast

riverbanks

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Yup,I too am waiting,not a tough system to solve,but the diverter valve,like you mentioned,seems a very good possibility

tnewman021 Enthusiast

tnewman021

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If you have the stock style quadrajet carb, there is a fuel filter in the base of the carb where the fuel line goes in, you'll need to use two wrenches to remove the line without twisting it, and I see River just beat me to it, ha.
Yeah I pulled that one out as well and it's clean

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riverbanks Senior Enthusiast

riverbanks

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Do you have a vacuum guage?put that on inlet of pump and crank motor over,if not, with inlet line removed from pump,add a extension to it,blow back thru it,have someone listen at fuel filler neck for gurgling,at the tank that is selected

tnewman021 Enthusiast

tnewman021

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Do you have a vacuum guage?put that on inlet of pump and crank motor over,if not, with inlet line removed from pump,add a extension to it,blow back thru it,have someone listen at fuel filler neck for gurgling,at the tank that is selected
No i dont

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tnewman021 Enthusiast

tnewman021

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Do you have a vacuum guage?put that on inlet of pump and crank motor over,if not, with inlet line removed from pump,add a extension to it,blow back thru it,have someone listen at fuel filler neck for gurgling,at the tank that is selected
Can I blow through it with my mouth or do I need a tool

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