bypassing the in tank fuel pump

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bypassing the in tank fuel pump

Postby peterpan » Mon Jun 16, 2008 6:27 pm

on my 75 vega i am running a mechanical pump and need to pull the in tank one out

i am thinking about just soldering a longer tube on where the pump was


any thoughts or ideas ?
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Re: bypassing the in tank fuel pump

Postby spyder_xlch » Mon Jun 16, 2008 7:24 pm

That's pretty much how you'd have to do it. I'd put some kind of baffle in the tank around the pick up and a sock on the end of the pick up.
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Re: bypassing the in tank fuel pump

Postby peterpan » Mon Jun 16, 2008 10:51 pm

i ended up just getting a compression fitting for 3/8 line and putting a peice on the end and set it about a half inch off the bottom of the tank

i have my fuel filter mounted before my fuel pump now and plan to ad another between the pump and carb later
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Re: bypassing the in tank fuel pump

Postby gerbsinmd » Mon Jun 16, 2008 11:05 pm

or just leave the pump in the tank if its any good. I had a buddy that ran a normal pump on the engine and the one in the tank for years. He only turned the one in the tank on for racing.
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Re: bypassing the in tank fuel pump

Postby Astre-mutt » Tue Jun 17, 2008 10:30 am

Peterpan, I assume that you are trying to keep the stock fuel line. If not I would think it mite be simpler, and better to mount the line at the bottom of the tank. You could weld, or purchase a compression fitting to mount to the tank. I believe this would also make the system self priming to the mechanical pump.

I'm planing on doing something similar on my car, but because of cornering force I'm putting a cone shape reservoir under the tank with a 3/4"hole in the tank for the gas to pass through.
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Re: bypassing the in tank fuel pump

Postby monzamess » Tue Jun 17, 2008 1:01 pm

The Iron Duke cars also used a mechanical pump and so maybe you could find one of those pickup tubes:

Image

P.S. Is a bottom drain really a good idea? Crud that gets into the tank could clog things up. Also seems like a safety issue in an accident and you can't stop the gas from coming out.
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Re: bypassing the in tank fuel pump

Postby Astre-mutt » Tue Jun 17, 2008 2:44 pm

monzamess wrote:
P.S. Is a bottom drain really a good idea? Crud that gets into the tank could clog things up. Also seems like a safety issue in an accident and you can't stop the gas from coming out.


All good points, in my case the the cone is similar to the rear sump on tanks set up for drag racing, but it will work for g-forces in all directions. As far as safety who knows. I had plan on having it as far forward as possible on the bottom of the tank, with the elec fuel pump tucked up in the rear axle tunnel. Only the 90 degree fitting, and a short piece of braided line would be below the tank. I would definitely use a cone shaped screen in the tank to prevent trash from entering the fuel line. Maybe not the safest system, but I would think it would be safer then the drag racing style where the fittings are at the rear.

The Iron duke pickup is a good thing to know.
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Re: bypassing the in tank fuel pump

Postby spyder_xlch » Tue Jun 17, 2008 7:26 pm

Just remember water is heavier than gas. If you have any water in the tank it will surely find it's way into that sump.
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Re: bypassing the in tank fuel pump

Postby peterpan » Wed Jun 18, 2008 1:25 am

ya the iron duke sending unit is a part i'm going to start keeping my eye out for

i used the 3/8ths compression fitting to put about a 6'' extention on the pickup tube where the old fuel pump was

then i used a long pry bar to adjust the pickup to a half inch off the bottom of the tank running the pry bar threw the filler neck

i thought about some kind of filter on the pickup tube but then i would have to drop the tank to change it so i settled for a see threw filter before my fuel pump and will ad another between the pump and carb later

i drove the car today with only a gallon of gas and it worked fine so far


i don't know if it would of done anything but when i removed the electric pump i just cut the power line to the pump off and was worried that it might cause a spark in the tank so i allso cut the power wire off the plug that plugs onto the sending unit just to eliminate the possability
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Re: bypassing the in tank fuel pump

Postby 78spyder » Sun Jul 20, 2008 1:39 pm

Anyone know what size pickup the iron duke uses? Looks like 3/8 in the pic, but I always thought they were 5/16.
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Re: bypassing the in tank fuel pump

Postby Jitterbugdude » Mon Jul 21, 2008 10:10 am

Is this for a stock 4 cylinder? if so, what kind of fuel pump are you using and where did you mount it?... If on the other hand, this if for a V8.... never mind!!!........ Randy B
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