Yanmar 2GMF20 Mystery Hose

[Stu Jackson]

Electric fuel pumps

It all depends on how it's wired. On many older boats, the electric fuel pump is wired so that it always runs when the ignition switch is on. On newer boats they complicated a simple matter and paralleled the fuel pump power to the glow plugs (don't know if you have them on your engine) and to an oil pressure switch. Once the engine was running and oil pressure was up, the fuel pump started running (again - if it had glow plugs). Because of the need to bleed the secondary engine mounted filter which usually has a bleed screw that needs to be either loosened or removed, many of us installed toggle switches on the fuel pump power to be able to single hand the bleed process without leaving the engine to go to the 1-2-B switch or the ignition switch in the cockpit, thus saving a mini-fuel spill. This experience is on Universal engines.

Electric fuel pumps are really handy for bleeding engines. Don't know if this applies to your engine, but here's what works for us: http://c34.org/bbs/index.php/topic,5558.0.html Please note that some engines are self-bleeding.

I agree that getting some hands-on help would be useful to you with your new-to-you engine. I know I did when mine was new to me. I asked everyone who'd listen, and even some who wouldn't! Once you get the hang of it, you'll wonder why anyone thought it was rocket science, 'cuz it ain't. And, there's so much more information available out there now than there was 13 years ago when it was new-to-me.

Good luck.

 

[wufibugs]

Thanks for jumping in, Stu. There are no glow plugs on the 20GM20F. That certainly explains the switch. When I was testing to see if the pump was pumping, I had to scramble to turn down the bleed screw. I am going to pay one of the diesel handymen here in the Marina to preside over the initial start up. BTW, there is an alarm that screams when the ignition key is in the on position. I assume that signals low or no oil pressure until the engine gets it pumping? He can help me motor over to the dock to have the holding tank pumped out. I will then have to sanitize that and the water tank. I have been reading Peggy's posts on that subject. I have always hated the smell of clorine, but I may have to "suck it up" here since she is not high on the other alternatives.

 

[Steve Dion]

There were no electric fuel pumps on the 2GM engines either. This has been a modification that I do not think it is a good idea (in lew of the manual pump). Many have installed electric pumps to bypass their manual fuel pumps. While this is fine to bleed the engine, it is not that big of a deal to do it with the manual pump and/or the key.

If you electrical system should fail your motor will cease to function with a manual pump. Having an electric & manual pump is not a bad idea as a backup to the manual pump in case of a failure.

The newer Yanmars have self bleeding systems, which is a nice enhancement when changing filters.

 

[druid]

Advantages of electric fuel pump: Ease of bleeding, can be shut off to (hopefully) stop the engine for example if oil pressure fails (the connection to the glowplug button is coincidental - the Idea is you press it to start the engine - once the oil pressure is up, you can release the button. You can wire it this way without glowplugs). You can use the electric pump for other things, like polishing or running a heater (probably using a separate pump, but that means you have a spare).

Disadvantages: doesn't run without electricity, more complex than mechanical.

I tend to prefer the mechanical cuz I like things simple.
druid