electric fuel pump with water separating filter, pull or push plus regulator where?

[sdowney717]

I am redoing my fuel system going from mechanical to electric. Tanks also have the anti siphon valves. And I do have them wired with the oil pressure safety switch.

I thought to put 2 water separating filters in front of the pump and mount a regulator on the pump then onto the carb.
I like the idea of filtering fuel before the pump and like the idea of 2 water separating filters, a 10 micron then a 4 micron then a pump and regulate the pressure down to 3 PSI. Pumps are rotary vane type. One is Holley red marine, the other a carter.

This is a dual engine with 2 tanks, so 2 pumps and 4 filters with a central selection valve.
Anyway would you expect this to be a problem?

I ran into a problem, the Holley side seems to pull ok, the Carter side has difficulty maintaining the prime, it will pump into a bucket then just stops moving any fuel. So I am going to have to troubleshoot why.

I could redo it to put the filters on the pressure side, or I could put one filter on the suction side and one on the pressure side. I dont like not having filtered fuel hitting the pump due to wear and perhaps water in the fuel rusting them.

How are these electric pumps normally setup?
And what do you use on the brass screw fittings for a sealer? I was using teflon tape but read that could be bad.

 

[sdowney717]

Re: electric fuel pump with water separating filter, pull or push plus regulator wher

I found the vacuum leak on a fitting on the carter side, it was on my valve selection manifold.
It only takes the smallest air leak to render a suction system like these pumps have to fail completely.

Too bad gas boats cant have fuel pumps in the tanks where they push and dont have to pull fuel out.

I also read that pumps should be within 12 inches of the engine and the pressure line 48 inches or less.
How do you think they measure 12 inches, 12 inches from the exhaust manifold? from the block?
How about 12 inches from the transmission?

 

[Bondo]

Re: electric fuel pump with water separating filter, pull or push plus regulator wher

It only takes the smallest air leak to render a suction system like these pumps have to fail completely.

Ayuh,... That's why ya design a fuel system with only 1 filter, 'n as little hardware, 'n plumbin' as Possible...
Less chance of vacuum leaks....

Merc mounts their electric fuel pumps to the forward starboard corner of the motor, just ahead, 'n under the exhaust manifold...

Donno where ya got the 1', 'or 48"s...

 

[sdowney717]

Re: electric fuel pump with water separating filter, pull or push plus regulator wher

from the USCG website. to be in compliance pump MUST be within 12 inches of the engine. How they define that maybe common sense. I managed to find a spot less then 12 inches away from the valve cover to mount the pump on the boat not the engine. I can see them looking at the motor and taking a tape measure and I though I better get this right, dont want a fine.
They must have seen it all, and they will know when it looks right and when it does not.
http://www.uscgboating.org/regulations/boatbuilder_s_handbook/fuel_standards_parto.aspx

FEDERAL LAW

183.566 - Fuel pumps: Placement

Each fuel pump must be on the engine it serves or within 12 inches of the engine, unless it is a fuel pump used to transfer fuel between tanks.

The 48 inch pressurized fuel line is also written somewhere.


I spent time out there and both pumps are working well now. They can pull thru the anti siphon valve, 2 water separating fuel filters and a mess of hoses and valves. Both filters are before the pump. I was very glad to get it working.

Advantage of cascading filters, is if one is overwhelmed with water, the other will work as a back up. With the old tank and todays lousy fuel seems like a good idea to me.

 

[sdowney717]

Re: electric fuel pump with water separating filter, pull or push plus regulator wher

Looks like the 48 inch rule is ABYC recommendation.
http://www.abycinc.org/committees/faq.cfm

I bet USCG has some kind of maximum length for fuel line based on hose size and amount that will spill if it is cut.

Q. Can a fuel pump be installed in, or near, the gasoline fuel tank to help eliminate vapor-lock?

A. Both ABYC H-24, Gasoline Fuel Systems, and the Code of Federal Regulations do, within certain parameters, permit the use of a remote fuel pump. The parameters are: the pump must be located within 12 inches of the engine that it supplies, and the hose from the pump output to the engine cannot exceed 48 inches. The objective of these requirements is to limit the amount of pressurized fuel hose in the boat. Any pressurized fuel hose that develops a leak can cause a significant fire and explosion hazard by spraying fuel into the compartment. The USCG has provided a grant of exemption to some boat manufacturers to permit the installation of the fuel pump in the tank. These exemptions are granted on a case by case basis and are based on a demonstrated ability of the system design to provide at least an equivalent level of safety. These designs may include a hose-within-a-hose design where the outer hose captures any fuel that may leak from the inner pressurized delivery hose, and a sensor causes an alarm to indicate that there is an inner hose leak.