The Stovebolt Site Forums The Shop Area Engine Shop Fuel Supply Problem

OK, This problem is driving me nuts, every time I think I have it figured out, nope I'm walking to the gas station again!

OK Here goes, 1951 3/4 ton Chevy, almost totally stock and unrestored, Daily driver.

I can be truckin along just fine, sput, sput, runs outa gas. When I re fill it, she only takes about 5 gallons and she is full. In other words I only have 4-5 gallons of useful fuel in my tank, until she runs out.

I know the gas tank is full as I have taken the sending unit out and there is fuel right to the top.

I tried replacing the fuel pump, still same problem. Previous owner had rigged a copper fuel line, with rubber lines at each end, I replaced both rubber lines, still when the fuel in tank gets below a certain level, my engine dies.

This all started when I ran out of gas one day, I didn't think I was out of gas, so I pulled the fuel line, that is when I discovered 2 things, no gas in tank, and the shut off valve under the tank was shot. Went to Napa, got a plug for the end where the shut of valve used to come out, and bought a new on/off valve that screwed into the fitting that screws into the tank.

OK Now it gets a little stranger, when I run out of gas, if I just pour a gallon, from my gas can, in the tank, forget it, she wan't start. If I pour in 2 gallons, she will start and maybe run for a block before dying again, (no gas). If I put in 3 gallons, she starts fine, I can get home, and to the station the next day to add 2 more gallons, then she's full.

This is driving me nuts, I've thought about replacing the whole valve assembly that screws into the bottom of the tank, but have not found a source.

A soon as it gets warm enough, I plan to replace the fuel line with a proper steel one, but I Don't see how that is causing this problem.


Any ideas?

Frank

Walking way to much in Spokane

Sounds simple. Your truck needs an exorcism. :p

Have you tried to run it with the cap off? Maybe some kind of vent problem. Anyway, welcome to the board. Let's see some pics of that baby.

Frank,
Check the fuel pump. It might not be working properly and needs a little extra help from gravity. Sounds like you are having the problem when the fuel level in the tank gets to about the same level as the carb and gravity stops helping to feed the pump. This would happen if the fuel pump is getting 'weak' and doesn't have enough suction to pull enough fuel from the tank and pump it up to the carb without the extra help from the difference in the fuel level in the tank and the carb bowl. Could happen!!!

'52 Ted

A friend had much the same problem. He changed fuel pump and filter, no difference. Put air pressure to the tank and it would run. Changed the fuel line and petcock and had no more trouble. Petcock and line looked clean and in good shape, but there was some thing wrong. Hope this helps.

Frank,
2nd thought. Check for a vacuum leak in the line, valve, and ALL fittings all the way from the tank to the pump since you were working in that area. Something else might have jarred loose when you were working on other things. It could give the same problem as the 'weak' fuel pump. Good luck.
'52 Ted

Ted 52,

I replaced the fuel pump a few weeks ago, seems to run exactly the same either way. I was surprised NAPA still had one in stock, glass bowl filter and all. I'm kicking myself now, because I didn't think to ask if they had the vacuum booster version. I heven't tried running with no cap, but I have tried removing the cap when it dies, then trying to start it, no luck.

Is there a replacement for the petcock, or is it something you take to the parts store, and cobble together from parts?

I amm planning on replacing fuel line, just hoping someone else would have some ideas.

Frank

Does it get gas from the bottom of the tank or is there a pickup tube in the top?

Pickup is in the bottom of the tank, smack dab in the center.

Frank

Hi Frank,

You wrote 'Went to Napa, got a plug for the end where the shut of valve used to come out, and bought a new on/off valve that screwed into the fitting that screws into the tank.'

Is the new valve screwed into the outlet that the old valve was screwed into, or is it in a different outlet than the original? If so, can you change back to the original outlet?

Ted

Hey 52 Ted,

OK The New cutoff valve is screwed into the same hole that the original fuel line was connected to. The original on/off valve hole was just filled with a plug. Im really considering a tubing bending kit, and double flare kit, then make my own original style fuel line. The original line is still there, The rubber hose that used to connect to the tank fitting is still on it, just shredded.

Frank

see another recent (same) thread. they sound alike. good old crud :mad:
http://www.stovebolt.com/bboard/cgi-bin//ultimatebb.cgi?ubb=get_topic;f=22;t=004756

i found a cheep 50 or so chevy once cheep because of a simular problem. cut to the chase, i finaly pulled the tank and found the washer out of a can of fuel dri or something would get sucked to the fuel pickup inside the tank.