Grain truck starting issue

Milk · Mar 16, 2020

I have an older gmc grain truck with a 427 gasoline engine that has been sitting all winter long in storage shed that won t start! It fired over once, now it s not firing at all! I replaced all spark plugs,still won t fire unless I pour a little gasoline down carburetor. I took gas line apart coming up from the pump, nothing coming out or into the fuel pump, plenty of gasoline in the tank also. As a last resort I tried sucking on the gas line coming into the fuel pump, cannot suck any gas. Any help or recommendations would be greatly appreciated!! Thanks!

Steve@Advance · Mar 16, 2020

Probably a bad fuel line at the pump or at the tank.

Could also be the pump. Try disconnecting the hose from the pump inlet, the pump should pump air. If nothing, the pump is bad.

All of the rubber (neoprene) components, hoses, diaphragms, carb components, were never intended to operate with ethanol gas. Sitting with ethanol gas in the system is even worse.

Chances are it will need a new pump and fuel hoses. The carb will probably need a repair kit and a good cleaning.

If it's a Holley, watch it closely for leaking gas as they tend to leak internally and externally.

If it's a Quadrajet, easy fix!

Milk · Mar 16, 2020

Thanks Steve!!

rustred · Mar 16, 2020

those 427's have a 4 v holly carb. plus a governor on the carb. used to clean and put kits in them a long time ago. about a 4-5 mpg engine.

Hobo,NC · Mar 17, 2020

If you determine you have a fuel supply issue check both sides of the pump, the pressure side (outlet) and the vacuum side (inlet).

Pressure side should have 2-4 lbs of fuel pressure
Inlet side should pull up to 15 to 17" of vacuum.

If the inlet side of the pump check good and you have issues with the pressure side look for issues with the fuel line from the tank to the pump you can also check the inlet side of the pump at the tank to it should check the same as checking at the pump.

They are no fun to replace the pump on confirm its a pump issue before you go there with an old school fuel pressure gauge that has a pressure and vacuum reading on it... That's why it has both
test on it :wink:

https://www.youtube.com/watch?v=EYWKo40FDH0

Milk · Mar 18, 2020

If you?re lucky to get that mileage!!!

Milk · Mar 18, 2020

Update: grain truck not starting issue. Thanks for all your suggestions on getting my gmc grain truck to start. I listened to all of your ideas and they worked! Found the break in the fuel line, fixed it, put the mechanical pump back on, blew air in the tank pressurized the system and it started rite up! Thanks a bunch!! I would have been dickering all day trying to figure it out on my own!!

Hobo,NC · Mar 18, 2020

Good deal...

My uncle helped me put my first mechanical fuel pump on he told me to get the bolts started good then rotate the engine a little then rock the pump till it primed...

I asked WHY he said back in the day when they were all 6V you would run out of battery before it would pick up the fuel...

Of course about all I have worked on are 12V but I remember what he said he was one of the best mechanics around...

Olliejunkie · Mar 18, 2020

Never thought of that. I put a little gas down the carb to get them primed. If I can I fill the bowl first.

Grain truck starting issue

Milk

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Steve@Advance

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Milk

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rustred

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Hobo,NC

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Milk

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Milk

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Hobo,NC

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Olliejunkie

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