Thread: Fuel Problem

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I have a 35 Ford Hotrod with 302 engine with 4bl Edelbrock Carb. I installed an electric fuel pump which is located near the fuel tank. The fuel pickup tube is from the top through the sending unit. Between the tank and fuel pump I have a small glass filter. From the tank to the filter to the fuel pump I am running 5/16 fuel hose, about 4 feet. From the fuel pump there is another couple feet of 5/16 hose that then hooks to metal fuel line and runs to the engine compartment. The metal line terminates where the original mechanical fuel pump was and there is about 1 foot of 5/16 rubber fuel hose that connects the metal line from the tank to another metal line that runs up around the water pump and along the valve cover and intake manifold to the rear of the engine where it hooks to a clear filter at the carb. Wow, I know this is long winded but I wanted to make it clear about setup before describing the problem. Now the problem: When I drive the car for anywhere between 5 and 10 miles or there abouts it starts cutting out until it finally stalls. When I look at the clear filter at the carb. there is no fuel in it. If I let it sit for a little while it starts up and the whole thing starts all over again. I thought maybe the first fuel pump was bad so I replaced with a Mr. Gasket fuel pump. The problem still exists. My question is, could this be a vapor lock problem? If so, how should the fuel line be run to the carb. Should I just move it a fuel inches from next to valve cover and intake manifold so that it isn't lying against the manifold and valve cover? At first I didn't think it was a vapor lock problem because I have plastic conduit covering the metal fuel line in the engine compartment and it hasn't melted. I figured that it would melt if it was getting hot enough to cause a vapor lock. I may of course be wrong. Any suggestions or input would be greatly apprecialted.

Thanks,

Teddy

Are you sure your pump is still pumping? I had had a few electric fuel pumps and seen others that would over heat from pumping and quit, till it cools a little then pumps again till it heats up again.
Are you sure your fuel line keeps pulling fuel form the tank? I don't know what you have for a tank, or tank fuel setup. Inside tank sock filter pluged?
I would run all hard line, and only enough hose to hook connections. As long as the fuel line does not touch the block or exhaust it should not get vapor block.
With the conduit over the fuel once it does gets warm, it won't cool down either! I'd remove it.

Pat

Originally Posted by teddy

...could this be a vapor lock problem?...

Yup... doesn't take a lot of heat to boil gas... much less than to melt plastic. You can get insulation to run your fuel line through will help a bit but I wasn't able to completely correct the problem until I switched to a bypass regulator so the fuel is always circulating... this route may be overkill and not cheap. As a start: insulate the fuel line and move it as far away from any heat sources as possible.

I can't find a link to the insulation I used.... I picked it up at the local roundy-round speed shop I think something like $40 for 12'. I'll try to post a picture tonight.... I do see some insulation from Earl's on Summit but this stuff is a different material and very pricey.

There will be other opinions too...

-Chris

If I read you right you have 4 feet of rubber 5/16ths between the tank and pump? ... sounds excessive, Just maybe that line is collapsing from suction.

^^^ good point

Originally Posted by HemiTCoupe

Are you sure your pump is still pumping? I had had a few electric fuel pumps and seen others that would over heat from pumping and quit, till it cools a little then pumps again till it heats up again.
Are you sure your fuel line keeps pulling fuel form the tank? I don't know what you have for a tank, or tank fuel setup. Inside tank sock filter pluged?
I would run all hard line, and only enough hose to hook connections. As long as the fuel line does not touch the block or exhaust it should not get vapor block.
With the conduit over the fuel once it does gets warm, it won't cool down either! I'd remove it.

Pat

I thought it may be a defective pump but I replaced it with another make and the same thing happened.

Originally Posted by Rank

If I read you right you have 4 feet of rubber 5/16ths between the tank and pump? ... sounds excessive, Just maybe that line is collapsing from suction.

I had the same set up with the mechanical pump without a problem. Do you think the electric pump has more suction then the mechanical pump?

Originally Posted by HemiTCoupe

Are you sure your pump is still pumping? I had had a few electric fuel pumps and seen others that would over heat from pumping and quit, till it cools a little then pumps again till it heats up again.
Are you sure your fuel line keeps pulling fuel form the tank? I don't know what you have for a tank, or tank fuel setup. Inside tank sock filter pluged?
I would run all hard line, and only enough hose to hook connections. As long as the fuel line does not touch the block or exhaust it should not get vapor block.
With the conduit over the fuel once it does gets warm, it won't cool down either! I'd remove it.

Pat

The tank is a poly tank. The pickup has no sock on it. It is a stainless steel tube that is part of the sending unit. It is cut at an an angle and is off the bottom of the tank about 1 to 1/12 inches. Also, someone told me that I need a pressure regulator. I thought that was only needed on fuel injection. I believe the pump only puts out 7 pounds of pressure.

Tomorrow I will try to move the metal line a few inches from the intake manifold and valve cover. It that doesn't work, I will try to eliminate the rubber hose from the tank to the pump or at the very least reduce the length of hose as much as possible. I didn't think the hose would colapse unless the pickup tube was blocked or clogged. Thank you guys for the suggestions.

Teddy

Fuel problem solved!!! The problem was two fold. The fuel tank vent line was crimped and the fuel filter inlet between the tank and electric fuel pump was partially clogged. It is one of those glass filters that can be opened and the filter cartiridge can be cleaned or replaced. I had been opening the filter to clean it but I was'nt removing the inlet section of the filter and couldn't see that it was clogged. I guess this is an example of over looking the simple things. The good news, is that the problem encourged me to to relocate the electric fuel pump to a better position in relation to the tank and short the hoses. All is good once again. Thanks for the help.

Teddy

Now, install a regulator to bring the pressure at the carb inlet down to 5 psi and you'll be golden. More pressure will not make more hp, it'll only over-ride the needle and seat, blow raw fuel into the intake and give you tuning headaches. Ask me how I know.