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Switching BACK to mechanical fuel pumps?

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  • Switching BACK to mechanical fuel pumps?

    I have older pre-vortec inboard mercruiser carbed 350's. They both run well, one of them was just rebuilt in fact.

    The problem I'm having is with the fuel pumps. Someone before me converted over to electric pumps, like these https://www.summitracing.com/parts/crt-p4389. That in itself isn't bad, but the conversion is terrible. First off they mounted them on the bulkhead between the engines and the cabin, so when the pumps are running they're very loud in the cabin. They also never included any oil pressure safety switch. All I have is a switch for each pump that I gotta turn on before starting and off after I shut down. And on top of that, they put pressure regulators in between the pumps and carbs. There is no need for these since the output of the pumps is 5-6 psi and thats perfect for my carbs. So I need to move the pumps to another location, re-wire/plum them, add the oil pressure switches. I want to use the bulkhead they're currently mounted on for electrical stuff.

    My current immediate issue is that my port side pump fails sometimes. Usually after a longer run at 2k rpm or above the engine will sputter and die. It usually will stay running at idle only. I checked the port fuel tank/filter/lines and found no blockage. The pump itself stops outputting fuel. I've taken it apart, cleaned it, check power... still does it. If I beat on it with my crescent wrench it'll start working again. This pump has failed at very inopportune times, like docking. Or today when trying to run with heavy following seas... loosing that engine caused lots of tense moments while I beat on that pump with my wrench.

    So, I'm thinking instead of replacing that electric fuel pump, and moving them etc etc, that I'll go back to mechanical pumps.

    Any thoughts?

  • #2
    Yeah, make it set up like it came from the factory. I hate it when someone cobbles together a cheap fix. Not only will you be more comfortable with the boat, it will be safer in the long run.
    If ya can't fix it with a hammer,ya got yourself an electrical problem.


    • #3
      Hopefully the original pump push rods are still in the block. You should be able to get new fuel lines . Or if there is a speed shop in your area they can supply you with good quality fittings and hose. Electric rotary pumps need to have clean fuel in the inlet side and are for pushing and not pulling.
      1980 Donzi 18'. 2+3 6.2 MPI Alpha 1


      • #4
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        Looked real quick today and the port side engine still has a fuel pump bolted to it. I'm not gonna fool with trying to see if it's still any good or not, so I'll just replace it. Dunno what to do about fuel lines... I know I'll likely use rubber from the tank to the pump(fuel filter in the middle there some place), being extra careful about routing. I didn't look at the starboard engine as I have to stand on my head to get to the right side of that engine. But I didn't talk to my engine rebuilder about possibly going back to mechanical pumps. Hopefully he put the push rod in there.. it's not the same block that was removed since it had been bored out once before.