tstorrie

I have an 84 camaro and I have been having problems with the car seeming starved for fuel after it gets hot. I have installed an inline fuel filter before the mechanical fuel pump and changed it many times before. Lately, if I remove the line from the filter, the fuel will pour out non stop. There is no in tank fuel pump, or any relays. The car is running worse and I can't figure out why this line has gas pouring from it with engine off and the gas cap removed? This should be a suction line from the tank, but fuel seems to be available non- stop. Any suggestions would be greatly appreciated.

Ozz1967

iTrader: (4)

The fuel in the line will run out until the line runs out of fuel, could be up to 1/4 gallon or so I'd imagine (the main fuel line) because it's gravity fed.

when the fuel gets hot, it boils causing vapor lock. When the fuel gets hot, it boils, causing air in the line. the mechancial pump is then literally "sucking air", causing a vacuum lock and fuel starvation. It's why the dealers started intalling in-tanke pusher pumps, to help keep fuel in the lines cool by pushing fresh fuel through.

When you disconnect the cap, that should relieve the pressure on the tank, so fuel will eventually stop coming out. Can't explain why ti won't stop on it's own unless it's still under pressure somehow.

five7kid

iTrader: (14)

The fuel pump inlet is below the level of the fuel tank, so fuel will continue to siphon until the tank is empty.

Are you using a factory type pump, which includes a return? Or, has your fuel pump been replaced with one that only has an inlet and outlet?

Ozz1967

iTrader: (4)

True about the line being below the tank. However you need to go up and out of the tank through the line, so shouldn't it only be what's in the line that comes out unless its under pressure?

tstorrie

Thanks for the help, I have a factory pump with the return line I am going to try and replace it just too see what happens. I might try a electric pump located outside the tank and eliminate the manual one altogether. I am thinking of getting a small gas can and seeing if the fuel stops flowing before the can gets full. I have spent so much money on the car this year, I may just leave it for the winter and start again in the spring. I would have liked to drive it this fall, but you just can't count on it right now. I have a fresh 350 vortec ready to go into it, but there is no sense of doing the switch until this problem gets fixed. Thanks again to those members who offer solutions to various problems on this site, at 100/hr shop rate I wouldn't have even gotten the car to the point it is now without reading these forms. You really do provide a service to car owners.

five7kid

iTrader: (14)

As long as the level in the tank is above the outlet of the line, the flow will continue until either the level in tank is below the outlet of the line, or the tank is empty. That's how a siphon works.

The only way it won't work is if the peak height of the line produces a "column pressure" that is greater than the atmospheric pressure. The fuel line in our cars doesn't come close to that.

Pretty good summary of the principles involved: http://en.wikipedia.org/wiki/Siphon

Edwardgp

Yep it will siphon out till the tank is empty.

SuperHawk996xx

iTrader: (1)

I sort of had this problem myself today. I have an 86' T/A with a decomputerized 350 Edlebrock carb and intake. I installed a glass fuel filter so I can actively see the fuel flowing in the line. But today the car would not start and I couldn't see any fuel in the line. I tried to start the car but no luck. Last year I cut out the charcoal canister opposite from the battery in the engine bay and left the vacuum line open that goes back to the tank. I used compressed air and blew air into the tank and tried to start again. This time everything worked like a champ! Anyone have any idea that happened? the engine was cold so I am pretty sure it couldnt have been fuel boiling.

colemanbarrett

mine doing the same thing so what type of fuel pump should i use. should I have a fuel pressure regulator or not if so what type

Ozz1967

iTrader: (4)

I understand what you're saying, but I was refering to how, in the stock set up, the lines come up and out of the top of the tank, before coming to the fuel pump if mounted externally. The fuel in the line between the tank and pump will train back into the tank when not running, causing the pump to run dry for a few seconds, thus burning out faster, which is what happened to me when I ran the holley black pump. I went through 3 pumps before I realized what was happening.

I installed an in-tank pump and almost 2 years later it's still running strong.

ZimGTA

Try putting the filter on the other side of the pump.