Which pump for a 650hp 540 N/A

Aeromotive or Weldon ?

I've currently got a mallory 140 that is dead headed ( I know not the way to go) and they only last about a year and a half and I'm tired of changing these things. Now I just put a new motor in and am having fuel delivery issues (pump number 3) , I think, so like the saying goes "it's always easier to do it right the second time. " I'm going to redo the system the right way and I've got a Nickerson carb on order. At least with those two things out of the way I can get this motor figured out.

Can you install a mechanical pump ? Will do the job, be cheaper, and less hose routing.

The smaller Mallory and Holley electric pumps don't seem to like todays fuel at all.

If going to a bigger pump/regulator that uses a return line, Cp Performance, Hardin Marine, and KEPP carry the same return fitting that splices into your fuel fill hose.

First off, why not a mechanical pump?
Most of the repeat electric pump failures I've seen were from improper mounting. Too high or far from tank. Where's yours mounted?
The Mallory 140 requires a regulator, so why not run a return line? I've never done it, but heard others here run the return to the fuel line in front of the pump. Makes plumbing easier, I'm sure.
Gary

Don't return it to frt of pump if you don't have to.

I just found the fitting I was talking about:
http://www.hardin-marine.com/product...uel-return.htm

Well guys thanks for the replies but if I had the oportunity to run a mechanical I definitly would be using one.
I've got a gen6 block , so no mech provisions. I'm stuck with the electrical.

I will look into the " t /fuel filler " thing but I don't thing I can get to the fuel filler line.
I might be able to weld a bung onto the plate that my sending unit is attached to. Unfortunatly I'm pretty sure I can't fit a -6 , only a -4 which I don't think is enough so maybe the -6 from a regulator then split into 2 -4's ?

The Mallory is mounted on the bulkhead just in front of the motor about even with the top of the tank. The reason I don't have a return line was I didn't think I had a way to return the fuel to the tank. now that I might be forced into it I WILL find a way.

There is a way to modify the raw water pump mounted mechanical fuel pump to deliver more fuel. CP performance sells a kit, or you can buy a carter M61045 pump and swap over the valve body.

Your return line needs to be the same size as your feed line when working with a return style regulator and a high flow electric pump.

There's your problem!
Mount it at the level of the bottom of the tank. Electric wont suction fuel well and will die prematurely if not mounted 1) near the bottom of the tank, 2) close to it, 3) and dont have a filter or fuel water separator before the pump.

[QUOTE=26scarab]
The Mallory is mounted on the bulkhead just in front of the motor about even with the top of the tank. [QUOTE]

SB thanks for that link! I had never seen that before.
Gary

Unfortunalty , it isn't possible to mount the pump lower, with the way the liner is laid out.

about 6 years ago with my first build up (625hp) 502 I went with the CP recommended upgraded fuel pump that runs off that raw water pump housing. I installed that and didn't have a fuel gauge and ended up detonating that motor and eventually took out a piston. So I won't even entertain that idea.
Electric is what I'm stuck with and so is installing a return line. I just have to make a decision on whether it will be an Aeromotive or a Weldon.

I am using the mallory adjustable return style fuel log 4302M

http://www.malloryracing.com/Product...minselection=6

It requires #10 in and out. My Holley Black Marine pump has 4 years with this setup. Fuel goes to the carb first and excess pressure is returned to the tank. Absolutely the best way to get max flow and max life out of an electric pump.

Pump is wired through oil pressure safety switch with a manual overide button in engine bay to prime fuel bowls after long layup without cranking motor.

I also have a fume detector with automatic fan and twin halon.

The fume detector will set the alarm just from the fumes released while the bowls fill after a long layup.

BTW, This regulator/log is not USCG approved, however to most eyes it just looks like a fuel log.