Installation of an Electric Lift Pump on a Yanmar 2GM20F

[Ralph Johnstone]

I recently had the pleasure of finding an external weeping fuel leak on the lift pump of my Yanmar 2GM20F. Now how much of a problem could it be to replace the lift pump ? With the engine location I have, bloody murder . A few inches at best to see around the starboard side of the engine. The only way to see in beside the engine is with a mirror. Removing the pump was not bad but installing another pump is pretty much impossible. When you peer inside the pump hole and see that the lift pump cam is only about 1/4" wide, not much of a target and easy as spit to miss it when the pump cam rider goes in.

Rather than pulling the engine just to install the lift pump, I'll install an electric lift pump. The first question which comes to mind is the delivery pressure. Yanmar specs their mechanical pump at 1.422 PSI.

How important is it to match this pressure and will exceeding this by a few PSI cause any problems ? I'm looking at a Seachoice CUBE (USCG ignition approved) which is 3.5 PSI.

Also, is the pump wired across the ignition switch or across the oil pressure switch ? The Seachoice also seems to be concerned about leaving the ignition switch on while the engine is not running. Is this a concern for a diesel ?

Thanks as always for the suggestions.

 

[Charles Erwin]

The Facet Cube FAC-40252 is 1 to 1.5 psi. Over pressure could be a problem if the pressure side tube and clamps are not up to it but doubtful you could over pressure anything else. Also - I do not understand how 1.5 psi represents a threat at key on - motor off.

Do you plan on a cover plate where the cam driven pump was?

Charles

Edit - By the way I think the motor driven pump specification is at idle so it is likely higher at 2800. Electrics are spec at max without regard to motor rpm

 

[Ralph Johnstone]

Do you plan on a cover plate where the cam driven pump was?

I've machined a small cover plate and that should go in reasonably easy. I will install studs in the block which will be easier than trying to insert machine screw into a gasket and then cover plate.

 

[Benny17441]

Are you sure there is not a panel in the engine compartment that could be removed or cut out to provide access to install a replacement pump. If electrical lift pumps were the ideal solution Yanmar and boat manufacturers would have incorporated them long time ago. Of the top of my head I can think of a number of drawbacks; 1) deplete batteries or loose electrical power the engine dies, 2) in a marine environment wiring, connector and fuses suffer from corrosion and voltage drops, there is an increase in maintenance 3) a mechanical pump gives warning when it is failing but an electrical pump could fail instantly without warning or worse yet exhibit random faults difficult to diagnose. I know some have installed them as an auxiliary to the mechanical lift pump mostly for bleeding air out of the lines. I guess my point is that I like simplicity and reliability; engine failure in a boat if it happens at the wrong time could be critical. Having an engine that does not require electrical power to operate and that will be less likely to cut off instantly is a big plus in my book. As you may guess my recommendation is that it is possible to replace the mechanical lift pump and there are true benefits in doing so. You may install an electrical to act as an auxiliary and then you might have the best of both worlds.

 

[Mark Maulden]

I use the exact same pump. Todays electric fuel pumps are very dependable and a lot of newer engines use them. The MTBF (mean time between failure) is extremely high. I also carry a spare. Also, my fuel tank, primary filter, secondary filter and injection pump are all within 2' of each other even with low fuel. I pulled the power on the pump and the engine keeps running. Loses some hp, but it's very useable if needed. Forget messing with a gasket on the cover plate if its a hassle. Small bead of permatex 2. The only issue concerning "leaving the key on" is the pump likes moving fuel through it. Leaving the key on for "awhile" wont hurt it. After all, thats what you do when you bleed...

 

[Ralph Johnstone]

I guess my point is that I like simplicity and reliability; engine failure in a boat if it happens at the wrong time could be critical. As you may guess my recommendation is that it is possible to replace the mechanical lift pump and there are true benefits in doing so.

I'm with you all the way on the simplicity idea. But this thing is "like a dog having carnal relations with a football in a hatbox".

I'm forced into this, and I'm not overjoyed about it. Maybe if I removed the heat exchanger and shifted the engine to port !

 

[Ralph Johnstone]

I use the exact same pump. I pulled the power on the pump and the engine keeps running. Loses some hp, but it's very useable if needed.

Mark,
Thanks and most interesting what you say about the engine continuing to run without power to the pump. I would think the check valves in a 3.5 PSI pump would have almost negligible resistance to forward flow and not hinder the injection pump. What kind of engine do you have ?

 

[Mark Maulden]

Make sure the pump is rated to pass fuel with no electrical power applied. Some are and some are not. Actually, the pump I use is has a higher pressure rating but same pump. But they should act the same. I have a 36 yr old Volvo MD 17C. It runs ever so sweet!! I have to say nice things about it......But it really does

 

[Mark Maulden]

And the fact that every part of my fuel system is "basically" at the same level, the injector pump will pump fuel from the tank if the electric pump fails. Hence, the reduction in hp....If your fuel tank is "a lot" lower than the engine, then the injector pump might not pump it.

 

[Mark Maulden]

Also, to replace your original lift pump, you could stick a piece of wood into the hole and on top of the cam lobe and turn the engine over and determine the low spot on the cam. When installing the pump, tilt it backwards (to stbd) when installing and push it in. You should feel some pump lever pressure on the cam lobe when you bolt it up. Totally by feel.....Might have to move some hoses etc???

 

[kloudie1]

No sympathy for ya, Ralph.. Changed mine on the 3GMF a few years ago..it was not easy! The access to the pump on the 34 is worse than yours! (granted not by much) .. Installing studs before ya try to reinstall is the ticket.. you can feel when the cam is right, just go slowly..
Note that all the (smaller size) Universal and Westerbeke sailboat engines use electrical lift pumps and have for years.. The HP injection pump cannot lift diesel from the tank by itself, it must have slightly positive pressure to work .. (like on tractors where the tank is a foot above the pump and there is no "lift pump".. The slightly elevated pressure of the "Cube" is not a problem..

Also note that sometimes just uniformly tightening the screws holding the top and bottom of the pump together will stop leaks that develop over time . You can do that with a 90 degree Philips ..

 

[druid]

Wow - that's crazy! How do you get at the pump to do bleeding?

druid

 

[kloudie1]

Bleeding is easy.. all ya need is a fingertip .. there is an access port for bleeding on the 34. Picture shows it.. but getting a hand in while holding the pump then wrenching the bolts down is an exercise in "touch" mechanics.. Pump is to the left , you can see the outlet hose going to the secondary filter..

 

[Ralph Johnstone]

Bleeding is easy.. all ya need is a fingertip .. there is an access port for bleeding on the 34. Picture shows it.. but getting a hand in while holding the pump then wrenching the bolts down is an exercise in "touch" mechanics.. Pump is to the left , you can see the outlet hose going to the secondary filter..

Kloudie,
I have forwarded your picture on to "Ripley's Believe it or Don't" as that has got to be the most impossible access in which to reach the lift pump. Fortunately, it's not something you do on a frequent basis.