Got the new plastic tank in, also new sending unit, new ful filler hose. new rubber line where the connections are all the way to carb! Can't get line primed up, put rag over filler neck push air hose in to get gas to flow as soon as i let off of hose fuel quits running out of line. So thought it was good enough can't get mechanical fuel pump to pick up fuel, put finger over pump it sucks when motor is running. With carb primed with fuel it runs for like 3-4 minutes then dies! No fuel....tired priming 6 times last nite! Tank has about half a tank of fuel!

Any ideas?

 

Why did you get all new parts in the first place? was there any issue happening before?.

 

Tank rusted up from setting......reason for new parts.

 

well, 7 ideas:

1) Improper fuel line routing - On carb vehicles the fuel line usually runs low along the inside face of a frame rail. So once fuel makes it up and out of the sender's pickup tube, through rubber hose section to steel line, the line drops down and runs along relatively low, to the rubber hose connection to the fuel pump's input. So gravity helps. Did you run the new line along too high?

2) An air leak, anywhere in the suction path. Lot easier to pull air in, than to lift a liquid.

3) A sender with a too-short pickup tube for your tank. If part of the pickup's sock filter is in air, air she will pull.

4) A weak fuel pump. Can test by clamping about 6 feet or so of 3/8" rubber fuel line onto the fuel pump inlet, put other end of hose into a gas can. It should pick it up within 15 seconds of cranking.

5) Fuel pump eccentric on camshaft worn down, so fuel pump arm has little reciprocating motion. I would assume on a 351C or 400 the eccentric is replaceable, but I haven't had either of those engines to know for sure.

6) Carburetor Bowl vent closed/plugged. Carb has to get rid of the air that gets pumped into bowl when pulling in fuel through the line.

7) Spirits. Truck was built over an old Indian graveyard. Can't help with that, check South Park.

 

If you can push air through the fuel line with air but the pump wont pump it, it sounds like a bad pump.

There's not that much involved with moving fuel in these trucks. Do you have a small electric pump you can hook up for a little while to confirm? Or even an old mechanical sitting up somewhere?

I hope when you changed tanks you wound up with a 33 gallon tank; I didnt and I pay the price every two years when my stupid fuel level sending unit needs replacement. There's only ONE place I've found that sells them...I see the 33 gallon units everywhere.

 

That explains a lot about TGM's problems

Make sure here aren't any leaks, air leaks, fuel leaks etc.. Clamps everywhere and if you have an inline filter vs a filter in the carb, make sure it doesn't leak. If the fuel pump has enough suction to feel it with your finger then it has plenty to suck a little fuel into the carb. Also check you oil for any gas contamination. I've heard that these old mechanical pumps can leak past the diaphragm and let fuel into the oil.

 

Thanks for all the help.....it be a few more days before i can work on it again! I will post the fix hopefully soon!!