Mechanical to electric fuel pumps

javalin390
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Mechanical to electric fuel pumps

Postby javalin390 » Sun Apr 21, 2019 8:17 pm

Trying to decide about making the upgrade or not to electric fuel pumps. Heard pro's and con's of both. The choice I am thinking of is the USCG approved Air-Tex 8337. It is capable of a max of 9 PSI and 30 GPH. Any one know what the GPH is for Chrysler 360's on plane? Some of the past posts expressed a concern that electric pumps can't keep up and lean the carbs out at extended higher RPM use. At 30 GPH, that is a lot of fuel ! Any thoughts?
Jim Elias
1974 37' SedanFlybridge
Twin 360 Chryslers.
Marblehead, Ohio

CaptainOpus
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Re: Mechanical to electric fuel pumps

Postby CaptainOpus » Sun Apr 21, 2019 8:41 pm

My understanding is that pressure is as important as flow. maybe even more so. 6 psi i believe. can't find the video on it. Good luck Chris

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Busia
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Re: Mechanical to electric fuel pumps

Postby Busia » Mon Apr 22, 2019 4:26 am

If you have engines with carbs, all you are doing is filling the float bowl as needed. Too much pressure is bad.
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Re: Mechanical to electric fuel pumps

Postby Fastjeff » Mon Apr 22, 2019 6:29 am

I have a LOT of experience with doing this, much of it learned the hard way. To wit:

First of all, there's a whole lot of E-pumps out there, many of which are absolute CRAP: they don't produce anywhere near the pressure and or flow they are supposed to. (Several of these clunkers wouldn't keep up with a 60 hp outboard.) Also, they must be marine acceptable and be located near as possible to the tank.

The one I finally ended up with is sold on Amazon: "Electric Fuel Pump High Performance Universal With Installation Kit Low Pressure 5-9 psi number E8012S". This pump works well BUT requires a fuel pressure regulator (Holley set at 5.5 psig) to control its high output pressure.

The next problem (opportunity, actually) is how to power it. USCG regulations require that a oil pressure switch be wired into the circuit, to shut off the pump when the motor stops. This can be handled with an additional "idiot light" switch added to the oil pressure circuit. I use a Bosch type relay to accomplish this, with the power to run the E-pump coming right off the battery (fused). The old voltage regulator circuit (HOT in run) was used to trigger the relay.

Finally--and here's the nice part--I used a momentary switch to bypass the oil pressure signal and allow the E-pump to run with the motor off. That allowed me to fill the carbs after the boat had been sitting for a week or so, which allows instant starting.

Jeff
"We live at the bottom of an ocean of air, not at the top." General Marvage Slatington

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bcassedy
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Re: Mechanical to electric fuel pumps

Postby bcassedy » Tue Apr 23, 2019 9:30 am

I spent (too much) time last season dealing with 3 separate fuel delivery issues on the starboard motor. One of them was that I couldn't get fuel to flow up at the end of the fuel line where it entered the carb. I remembered from the old Marinette site that Jeff had mentioned electric fuel pumps as a replacement to the old mechanical style found on 318's. Try as I might , including the momentary switch to prime the carbs PLUS the inclusion of a oil pressure switch at the back end of the engine <where the oil sending unit's mounted> I just couldn't get a sustainable amount of fuel at the carb. What I hadn't done is mount the electric pump near the tank as Jeff indicates above. I'd mounted the pump down low (actually on the shelf in front of the engine) but I guess these units (mine was intended for use with a new Edelbrock carb - 6 psi delivery) - are better at pumping longed distances than bringing fuel to them. Long story short(er), I found that the mechanical pumps were/are still available online (Ebay). Installed that, new gas and carb (the 3rd "delivery issue" that needed addressing), and engine fired right up!

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Re: Mechanical to electric fuel pumps

Postby Fastjeff » Wed Apr 24, 2019 6:37 am

That's why I recommended that particular pump. It can draw fuel 15 feet through a 3/8 hose. Used it to pump out the tank on my bow rider. Most E-pumps out thee can't begin to do that.

Jeff
"We live at the bottom of an ocean of air, not at the top." General Marvage Slatington

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Re: Mechanical to electric fuel pumps

Postby Joe » Wed Apr 24, 2019 7:19 pm

Hello, First I have been a mechanic for 30 years. I have owned , and worked on many boats. I would not consider an electric fuel pump an "up grade" on a carbureted system. Put a stock pump on it and drive it.
1988 sedan flybridge. Black / White. 318 240 hp Aluminum aft deck hard top. Louisville Ky . Tartans landing. " KNOCKEFELLERS"

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Re: Mechanical to electric fuel pumps

Postby Fastjeff » Thu Apr 25, 2019 6:56 am

Good advise, for mechanical pumps are more reliable in the long run.

The main advantage of the E-pump is priming the carb.

Jeff
"We live at the bottom of an ocean of air, not at the top." General Marvage Slatington

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Re: Mechanical to electric fuel pumps

Postby seef158 » Thu Apr 25, 2019 7:58 pm

Fastjeff wrote:Good advise, for mechanical pumps are more reliable in the long run.

The main advantage of the E-pump is priming the carb.

Jeff


I myself am a fan of seeing some oil pressure on the guage before my engine fires up so I've never let a long crank time scare me. If your engine is tuned up and you have a decent battery the mechanical pump will prime the fuel system and you'll fire up no problem.
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javalin390
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Re: Mechanical to electric fuel pumps

Postby javalin390 » Sun Apr 28, 2019 7:34 pm

I suppose the long crank time is what's bothering me. After living with, or being spoiled by, the luxury of fuel injection in modern automobiles, which fire up immediately, getting my boat to fire up after sitting a week or two seems like it takes forever. The port engine does fire quicker than the starboard though. Jeff, you mentioned you used the E8012S. The E8337 is supposed to be USCG approved. All the advertising I have looked at does not state that the 8012 is. Any thoughts.
Jim Elias
1974 37' SedanFlybridge
Twin 360 Chryslers.
Marblehead, Ohio