1985 C20: Carb not getting fuel

[1985C20FLATBED]

Hello all,

I have a 1985 C20 with a 350 and auto transmission. Truck is completely stock.
I have power to the key and the truck wants to start. I am now looking into the carb because we don’t think it’s getting fuel. It has a new fuel filter and I have a new carb mounting gasket on the way. Any other suggestions? Thanks!

 

[legopnuematic]

Pull the fuel line off the carb and insert into a bottle, crank truck for a few seconds.

It should fill the bottle up a fair amount. If it does the fuel pump is ok and getting fuel to carb, if it doesn’t fill the bottle or very little, check fuel pump and connections from pump rearward.

 

[1985C20FLATBED]

Thank you. I gave that a try and a good bit of fuel came out, so I believe the pump is good.

 

[1985C20FLATBED]

What do you think I should look for next?

 

[legopnuematic]

What carburetor is on the truck?

If you have good flow to the carb, hook the line back up and crank for a few seconds, then while staring into the throat of the carb (likely will have to Hold the choke flap open), cycle the throttle lever on the carb a couple times, this will pump the accelerator pump. When you work the throttle you should see fuel spray.

If you do see fuel spray, that says the accelerator pump is working and that the needle and seat is allowing fuel into the bowl.

 

[Sad Sack]

Should be a long paper gas filter. Did you put it in backwards?

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[1985C20FLATBED]

I put a new filter in, ill check again but pretty sure its not backwards

 

[1985C20FLATBED]

What carburetor is on the truck?

If you have good flow to the carb, hook the line back up and crank for a few seconds, then while staring into the throat of the carb (likely will have to Hold the choke flap open), cycle the throttle lever on the carb a couple times, this will pump the accelerator pump. When you work the throttle you should see fuel spray.

If you do see fuel spray, that says the accelerator pump is working and that the needle and seat is allowing fuel into the bowl.

 

[1985C20FLATBED]

No fuel spray from what I can tell, don't smell gas either

 

[Matt69olds]

Fill the float bowl with fuel. Try and start it. With the float bowl full, it should run long enough to pull fuel from the tank. If not, check the fuel lines. Make sure you don’t have one kinked, or corroded.

 

[CalSgt]

Fill the float bowl with fuel. Try and start it. With the float bowl full, it should run long enough to pull fuel from the tank. If not, check the fuel lines. Make sure you don’t have one kinked, or corroded.

Any time my carb lost its prime I would need to pour fuel straight into it to get it started. After a start it would stay primed.

Also

At one point my tank switch valve went bad, it would lose prime trying to suck air from whichever side tank was empty so I bypassed the valve and only used one side.

 

[1985C20FLATBED]

Fill the float bowl with fuel. Try and start it. With the float bowl full, it should run long enough to pull fuel from the tank. If not, check the fuel lines. Make sure you don’t have one kinked, or corroded.

How much fuel should go in the float bowl? I've read about a cap full but want to be sure

 

[1985C20FLATBED]

Any time my carb lost its prime I would need to pour fuel straight into it to get it started. After a start it would stay primed.

Also

At one point my tank switch valve went bad, it would lose prime trying to suck air from whichever side tank was empty so I bypassed the valve and only used one side.

My truck has one tank so I think I should be ok

 

[Matt69olds]

How much fuel should go in the float bowl? I've read about a cap full but want to be sure

I have no clue how much fuel a Q-Jet float bowl will actually hold. I’m guessing a 1/4 cup or so.

 

[Ricko1966]

I have no clue how much fuel a Q-Jet float bowl will actually hold. I’m guessing a 1/4 cup or so.

If it's s qjet with a vent hose to the charcoal cannister.,I pull the vent hose off at the carb,and fill the carb through the air horn vent using a mustard bottle or dish soap bottle full of fuel,until fuel dribbles out the vent hose barb. Never measured it,I will next time. Fill where the funnel is until fuel starts to dribble out the red circle.