Thread:

Fuel system question?

Just installed a holley electric fuel pump in my 73' tahiti jet. I mounted it to the transom just above the jet bowl. Its being fed by 2 side tanks, the hoses come right out the top along the transom about 2 feet to a T fitting and into the pump. I only run 1 tank at a time using valves at the tank. Im having flow problems, sometimes none. This seemed like a good way to go what am I missing. is the pump not able to pull from the tank ? seems like a very short run. what if I run the hose along the bottom then up to the pump will it then siphon properly. Im lost how should I have run this.

I would try mounting fuel pump lower, maybe along side of pump bowl on transom or along side a stringer. I've always tried to keep fuel pumps as low as possible in relation to fuel tanks. Check and make sure you have a good ground as well.

Originally Posted by sox

Just installed a holley electric fuel pump in my 73' tahiti jet. I mounted it to the transom just above the jet bowl. Its being fed by 2 side tanks, the hoses come right out the top along the transom about 2 feet to a T fitting and into the pump. I only run 1 tank at a time using valves at the tank. Im having flow problems, sometimes none. This seemed like a good way to go what am I missing. is the pump not able to pull from the tank ? seems like a very short run. what if I run the hose along the bottom then up to the pump will it then siphon properly. Im lost how should I have run this.

Electric fuel pumps are pushers and not pullers with the exception of Weldon. It needs to be primed to push the fuel to the carb. You need to lower the pump as low as possible to the tanks, to allow gravity to feed it and prime it.

Originally Posted by Ol Blue

Electric fuel pumps are pushers and not pullers with the exception of Weldon. It needs to be primed to push the fuel to the carb. You need to lower the pump as low as possible to the tanks, to allow gravity to feed it and prime it.

As stated, electric pumps push better than they pull. Ideally the tanks would have the outlet in the bottom, and the pump mounted below the outlet.

Thanks guys. You are confirming all of my thoughts. My concern with mounting it down low on a stringer is all the water that splashes back there. Is this a concern or can the fuel pump take being in some water from time to time.
thanks again for the replies, very helpfull.

Originally Posted by sox

Thanks guys. You are confirming all of my thoughts. My concern with mounting it down low on a stringer is all the water that splashes back there. Is this a concern or can the fuel pump take being in some water from time to time.
thanks again for the replies, very helpfull.

I put my relay & circuit breaker kit in a small box to keep it from getting wet.

Originally Posted by Shaun

I've never understood all this talk about needing to mount a pump low so that gravity will feed it. My pump is mounted below my tanks but i run a filter/water separator up on the transom above the jetpump, above the fuel tanks. So my pump has to pump the fuel up the tank straw, across the transom, fill the fuel water/filter separator and then down to the pump. I've run Mallorys pumps like this for 15+ years, and now this year i just changed to an Aeromotive pump and I have never had a problem. Even if I change my filter or drain the system the pump never has had a problem pulling fuel.

I think your problem is else where personally, mounting your pump/lines/filter/whatever lower may band-aid the problem but something just doesn't seam right. That's just my opinion, i'm no expert.

Shaun, Weldon says you can mount a Weldon pump on top of a fuel tank and it will pump. None of the other Mfgs will say that including Aeromotive.

Originally Posted by Shaun

I've never understood all this talk about needing to mount a pump low so that gravity will feed it. My pump is mounted below my tanks but i run a filter/water separator up on the transom above the jetpump, above the fuel tanks. So my pump has to pump the fuel up the tank straw, across the transom, fill the fuel water/filter separator and then down to the pump. I've run Mallorys pumps like this for 15+ years, and now this year i just changed to an Aeromotive pump and I have never had a problem. Even if I change my filter or drain the system the pump never has had a problem pulling fuel.

I think your problem is else where personally, mounting your pump/lines/filter/whatever lower may band-aid the problem but something just doesn't seam right. That's just my opinion, i'm no expert.

It's not a gravity feed it a siphon effect. Always try to place the pump below the tank pickup.


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The shut off valves need to be t the Tee not the tanks.


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