Fuel only gets to engine when tank is out of the vehicle

[Challis350]

Hi all. I have a 1986 GMC C2500 with a 350 & Quadrajet carb. Was running perfectly before i started work on it.

I changed the fuel tank over the weekend as the old one had become rusty and was leaking fuel. What i thought would be a one day job took three as the mounts and the tank straps were in awful condition. I re-used the original sender unit as it was working, put all the electrical connections back in place and re-used the old hoses as these seemed to be in good condition.

I go to start the truck after cycling the ignition a few times to get the fuel pump going. Truck starts....but it is not happy. A lot of hiccupping before it gets going. The engine will run, but only if I keep the accelerator pedal held down. As soon as I let off the gas the engine dies. It doesn't even try to idle.

All the initial hesitation of starting points to a fuel supply issue, but then the truck wouldn't roar with the accelerator down if it wasn't getting enough fuel?

I'm struggling to understand how me replacing a fuel tank has lead to a lack of engine idle. Any thoughts?

*EDIT: WONT START NOW*

Thanks

 

[JamesMilk]

I just replaced my fuel tank, I would pony up the cash and replace the sender unit, she's probably clogged somewhere.
You could have jostled something loose that wasn't causing issues in the old tank.

 

[fast 99]

Could have picked up some crud. If air is available remove the idle screws counting the turns and put air pressure to the holes. Just a couple shots might do it. Reinstall the screws and try the idle again. Alternately use carb cleaner in those same holes.

If it is in the idle circuit might be able to tell which side is not working by dribbling fuel in each primary side on the air horn. If restricted should idle better temporarily.

 

[WP29P4A]

I would assume disturbing that much rust and sediment while changing the tank could send crud down stream, good time to change the fuel filter and check the screen in the carb, where the fuel line connects, if it has one.

 

[Snoots]

re-used the old hoses as these seemed to be in good condition.

Mistake Number 1.

 

[Challis350]

I just replaced my fuel tank, I would pony up the cash and replace the sender unit, she's probably clogged somewhere.
You could have jostled something loose that wasn't causing issues in the old tank.

How can this be if I am able to redline the engine? Surely the engine is getting the fuel it needs?

 

[Challis350]

Could have picked up some crud. If air is available remove the idle screws counting the turns and put air pressure to the holes. Just a couple shots might do it. Reinstall the screws and try the idle again. Alternately use carb cleaner in those same holes.

If it is in the idle circuit might be able to tell which side is not working by dribbling fuel in each primary side on the air horn. If restricted should idle better temporarily.

I've seen this suggested on other posts. I've stolen a bottle of compressed air from the office and will give this a go tonight!

 

[Soundmound]

I've seen this suggested on other posts. I've stolen a bottle of compressed air from the office and will give this a go tonight!

You didn't steal it because stealing is illegal. However, misappropriation is standard corporate practice or as progressives would state - a redistribution of CFM's has occurred to those lacking lolol.

 

[75gmck25]

Did you also replace or work on the fuel filters, or run the engine with the air cleaner off? Sediment/junk can get under the needle and let the engine flood, but it will usually run fine at higher rpm because it can burn the fuel and not flood out. You can get similar symptoms if you suck something into the carburetor Venturi area and block air flow.

 

[Challis350]

OK so the problem appears to be getting worse. I can't start the truck now so this all points to fuel starvation. Looks like it's another cold weekend under this truck!

 

[Arizona Ranger K5]

Remove your gas cap, see if it idles then. New tank may have a problem with vapor lock. If that's the problem, get a 'vented' gas cap.

 

[fast 99]

Check for kinked hose where it goes over the frame.

 

[DoubleDingo]

One thing that came to mind, you said it took three days. You used the old sending unit, the fuel in the lines could have congealed in those three days, and the debris from the tank could also contribute to clogging. That, and you used the old hoses. Get a new sending unit and hoses, replace any filters there are, definitely in the carb, but also any in-line filter if there is one.

 

[AuroraGirl]

You didn't steal it because stealing is illegal. However, misappropriation is standard corporate practice or as progressives would state - a redistribution of CFM's has occurred to those lacking lolol.

I mean, you just dragged politics into this for no reason, but you actually made a progressive point right before the dig.

Plus the amount of mergers, takeovers... are increasing way too much. Too few competition. We broke up standard oil when it was way way way way way less put together as exxon mobil or disney etc


misappropriation is standard corporate practice

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[Challis350]

One thing that came to mind, you said it took three days. You used the old sending unit, the fuel in the lines could have congealed in those three days, and the debris from the tank could also contribute to clogging. That, and you used the old hoses. Get a new sending unit and hoses, replace any filters there are, definitely in the carb, but also any in-line filter if there is one.

Yup going to do all of this this weekend. Thanks for coming back and posting.