Dennis Moore

You need a return line to the fuel tank to make an electric fuel pump last. When the needle and seats close (in the carburetor) the fuel pump can't pump any fuel and the electric motor gets hot (called dead heading the fuel). Installing a fuel return line allows the fuel pump to flow continuously keeping the electric motor from overheating and burning out. This not only allows the fuel pump to flow fuel easily, but also keeps fresh/cool fuel in the fuel line (helps prevent vaporlock). A regulator placed between the carburetor and the fuel tank (on the return line) will bleed off excess fuel pressure (except for the 7.5 psi that the carb needs).

The small plastic line on the pump is not a return line but it should be routed to the flame arrestor to make the Coast Guard happy.
Dennis Moore

mcollinstn

mechanical pumps will work well on that aplicatin and have no odd side effects.

You should have a warning horn wired into the temp/oil press circuit to alert you to conditions where you should shut it down. Shouldn't be relying on fuel starvation to alert you to an oil filter falling off...

Your electric pumps (if you MUST keep them) are most likely failing from heat. Wait, Dennis already addressed this. Yes, an after-pump regulator set to a lower pressure than the one ON the pump will work. Get a bypass style like he says, and run the bypass all the way back to the tank. Another thing to help your pump is a pump control box that lowers the voltage to the pump at low engine speeds to lower current draw AND pump heat (otherwise it runns FULL BLAST all the time including at idle).

I'd still go back to mechanicals unless you are running blow-thru supercharger...

p4-33

OK, seems the majority of you are recommending mechanical pumps...

I bought my boat already rigged with HP500's and the Holley Blue set up, so I need to understand what the original config looked like. I have Gen VI blocks, so no fuel pump boss on the block. Some HP500's had the mech fuel pump running off of the raw water pump, but I've not got anything on mine where a pump might mount.

My Fountain is an '86 that was repowered with HP500's at the end of '98, and I think 420's came out of it. My guess is that my external components (raw water pump included) came off of the old motors, which had mech pumps mounted directly on the block, and the easiest way to plumb up a fuel system was to go electric.

Looks like my only choice if I were to do mechanical pumps would be to switch out my raw water pumps with ones with mechanical pump provisions. This doesn't sound like it's getting any less expensive...

So to make an electric system last longer than a season, I need to return bled off pressure back to the tank. I will need to add a return line fitting to my tanks, or to the pickup/sender assemblies. I'll need to look at how feasable this is.

Nothing is ever easy. ;^)

Thanks for everyone's input.

Brian

Krumbsnatcher

I just completed this a while back, and I also documented the project for others. Here it is, hope it helps.

http://www.offshoreonly.com/forums/s...fuel+regulator

p4-33

You gotta love this place... From problem statement, to the confirmation phase, into concept, prototype, and finished design in a day and a half.

Some people spend MONTHS on this stuff!

CP Performance has all of the parts, and can have them here by week's end. Ramchargers may even have parts locally. I just need to confirm my fuel tank filler hose dia.

Thanks Krumbsnatcher - pictures are worth a thousand words.

Brian

22Pachanga

I agree I am changing from a Mark IV block to a Gen VI this winter and the fuel system was something I was giving a lot of thought to, and now all the questions have been answered!

Just have to ge the parts and put it all together.

Scott

Cord

I have Mallory electric pumps. So far no problems. I first set the system up without return lines and after hearing about so many problems I added one. Because I have dual tanks, I ran dual pumps so that there would be some redundancy. After adding the return line, I hear a noticable difference in how much the pump labored after it reached pressure.

Some other tips: do not run the power from the dash to the pump. Run the power from the switch to a relay. Power the relay directly from the battery with a fuse between them. 14g wire is the absolute minimum to use for this circuit. Having the oil pressure switch cut out is ok, but again, use them to control the relays, not the pumps. Although redundant with oil pressure cutout, if you run the power through the kill switch do it the same way. Use it to control the relay.

p4-33

Hello again,

I dug up this old thread because I'm FINALLY going to get this done. It *is* winter in Michigan, afterall.

I have 1/2" barb x 2" tees for my fuel fill hoses, plenty of 1/2" fuel hose for return lines, motors and cockpit out of boat, so plenty of room to work. I still haven't nailed down the pump setup, however.

I'm leaning towards Malloy Comp Pump 140's, with return regulators. Here's the dilemma: Mallory sells a 4140M package that has an anodized/marinized pump (M) but it comes with a 4207M non-bypass regualtor. They also sell a 4142 package (no M) that is an automotive application, and it comes with a 4309 (also no M) 2 port bypass regulator. They don't sell the marine 140 by itself, nor sell them in a package with a marinized bypass regulator.

I could buy the 4140M package, pitch the 4207 ($90x2), and buy 4307M marinized 3-port bypass regs separately ($100x2). That's option #1.

Option #2 is to go with the automotive 4142 pkg, with a 2-port bypass regulator, and ignore that it's not USCG approved. Mallory tech support tells me the primary difference is marine (M) components have an anodized coating, as well as the additional test time to meet USCG certs. The boat stays in the garage, and RARELY will see saltwater, so I'm not too concerned about corrosion. I just have a hard time with breaking the law, even tho it's a minor infraction and may never be noticed. But you never know when you might run across a Coastie with a woody against go-fasts.

Option #3 would be to run Mallory 110's (4110M) internally regulated at 7 (or so) psi, and skip the external regulators.

I'm leaning toward opt #1, but not crazy about having spare stuff I'll never use. Anyone looking for 4207M non-bypass regulators? Brand new, cheap.

What are you folks doing for electric fuel systems?

Sorry for the long winded post. Just want to do things right.

Thanks,
Brian

HP350SC

p4-33

I have (1) brand new 4140m kit that came with my whipplecharger HP500 kit. Also have nicely made up relay/wire harness assy. and wiring diagram that comes from whipple for this pump. I ended up modifying my sea water mounted fuel pump so don't need this setup. How about $190+shipping for all? Call me at 503-201-9488 if interested. I post regularly at Hotboat.com (same user name,HP350SC)

HP350SC

By the way, the Holley pumps are junk in the marine environment. Pump portion corrodes up internally.