[30Irwin]

Hello folks,

on the weekend I was rewiring a new stereo onto my DC panel. I found a switch that made good sense: the DC Outlet switch. When I looked at the back though, there was another, hefty (maybe 12 gauge) line running off the switch. Tracing it, I found it connect 12 V+ to an electric fuel pump. Huh: why would an electric fuel pump be switched on the DC panel?

I've had the boat for 3 months and have started it up many times (over the warm summer) without too much issue: just a little slow to fire. On all these times I am sure that DC line has been switched off. I have never had an issue where the engine cuts out. This weekend I tried starting with that switch on, and I think it started up much faster.

I'm no mechanic, but I'm thinking that electric fuel pump aids in building some fuel pressure, which is particularly valuable for a faster start, but not essential when the engine's running and drawing fuel using the mechanical pump.

Am I on the right track, here? Thanks!

 

[JimsCAL]

If the engine ran without the electric pump on, you must have an engine driven fuel pump also. I would guess a previous owner added the electric pump to aid in bleeding the fuel system. The faster starting is not related. The mechanical (or electric) pump just delivers the fuel from the tank to the high pressure injection pump.

 

[catamount]

I have a 2QM15 also -- it does have a mechanical lift pump and does not need an electrical fuel pump. Thus I agree that the electric fuel pump is probably for bleeding your filters or polishing the fuel. The hard starting is likely due to low compression, thus it takes a little extra cranking to get it heated up enough to ignite the fuel. These are old engines, production of them was discontinued over 25 years ago! Oldies but goodies.

 

[30Irwin]

Thank you gentlemen; this makes sense.

 

[RichH]

Usually there to more easily air bleed after filter change ... plus can be an emergency backup to the mechanical lift pump if one of its (poppit type) check valves fails.