If you don't have bungs in your tank for a return line hookup, you can install a tee in the tanks "vent" hose near the tank. Hook your return line to the tee.

I have been told that 5 to 5.5psi fuel pressure at WOT is okay. If it goes under 5 than you need to upgrade. Also may want to verify that your electric pressure gauge and sender are correct with a mechanical fuel press gauge.

Eric

It you want to run a mech. pump buy a Carter HV automotive punp and bolt the Carter bottom to the stock marine top. This is what CP performance sells as HV marine marine pump. This is what I use on my 540.

KChotboat,
That is exactly what I did and had just about Zero fuel pressure !


Checkmate,
I've heard about that but didn't know if it worked.

Mine works fine. You need to make sure the sea water pump is in good order since they do wear.

I was having problems with my Holley marine pumps (blue one and black one) The red pump would run all day, but you couldn't wind the motor up without the pressure dropping dangerously low. The lower output of this red pump apparently wasn't effected by the wiring.

After some resaerch, it turns out the problem was low voltage which can kill an electric pump. At WOT, there's no dead head problem, it's when your idleing that it causes the problems.

Turns out the long run of wire from the ignition switch to the safety switch and then to the pump was causing too much voltage drop. The solution, fuel pump relay. This mounts close to the battery and then gets a signal from the safety switch and then sends the voltage to the pump with a heavier and shorter run wire. Painless Wiring carrys them, part #50102, they're only about 25 bucks. You can see all the stuff they carry at www.painlessperformance.com

Craig

Ok, I called mallory with some questions regarding the filtering requirements of their pumps (forgot to install it before the pump and wanted to know how critical this error was). Anyways, the tech was adament that I would destroy the pump. I'm thinking return line-but the pumps have a internal bypass. The tech said that the gearotor style pump is absolutly incapable of lifting fuel. I asked about manually priming the pump and using a check valve. Doesn't matter. The pump can't lift the fuel. Basically, unless the pickup was below the tank and the pump was mounted below the tank, it would burn up. I asked how the pump would burn up. He said that the gear would gall on the aluminum creating too much drag and that the motor would over heat and fail. So of you guys running electric pumps, how many have had problems with the gearotor style when mounted above the tank?

KCHotboat, Do you know what the stock pump is rated at, as far as GPH? Verses the Carter HV pump? I also am trying to determine whether I need to feed my 509 more fuel or not. I don't think I do. My old Gaffrig fuel pressure gauge says 7psi at idle and 5-5.5psi at WOT. But I plan to verify that pressure with a mechanical gauge.

Eric

When I started looking for fuel pump answers Holley echoed the same thing as Mallory. The pump has to be mounted below the tank. I asked what pump he'd recommend for mine, and he said since they have to lift a little, he couldn't recomend one They make a "marine" pump, yet there's no application???? How many boats do you know of that the suction from the tank doesn't come out of the top. I thought this was actually a CG requirement, maybe not though. Anyway, I made a bracket that mounts the pump down at the bottom of the center pod, but it does have to do that intitial lift out of the tank. A lot of guys I know run them and they survive for years. They just have the relay that I spoke about earlier and so far, so good.

Craig

OK, 2 THINGS 1st I SEE ALOT OF GUYS SAYING TO RUN 1/2 IN FUEL LINE FROM THE TANK TO THE PUMP AND TO THE REGULATOR ARE YOU GUYS PULLING THE TANKS OUT AND CHANGING THE PICK-UP TUBE TO? MOST BOATS COME WITH 3/8 PICK-UP TUBES IN THEM, IF YOU LEAVE THAT AT 3/8 YOU COULD CHANGE THE LINE TO 2 INCH FUEL LINE IT DOES NOT MATTER,FUEL LINE SIZE GOES BUY THE SMALLEST SIZE IN THE SYSTEM,3/8 PICK-UP + 1/2 FUEL LINE ALL THE WAY TO CARB =3/8 FUEL SYSTEM.ONLY THING THE 1/2 INCH LINE IS DOING IS ACTING LIKE A LONG FUEL LOG.
AND THE OTHER THING IS THAT ELEC. FUEL PUMPS ARE MADE TO PUSH FUEL NOT SUCK AND PUSH,BUT IN ORDER TO DO THAT THEY WOULD HAVE TO BE MOUNTED SO LOW IN THE BOAT THAT THEY WOULD BE MOUNTED TO THE BOTTOM AND THATS NOT A GOOD IDEA.WERE ARE YOU GUYS MOUNTING THE PUMPS.

Mine are mounted close to the pickup, right on top of the tank. My pickups are 1/2".