Questions on Yanmar 2GM20F
 

My 1990 Dana has a little over 800 hours on the 2GM20F Yanmar engine. This
summer it got a lot of use and ran well. However, during the last week I
have developed what I assume is fuel feed problem. I started the engine up
and shortly it started to cough . I drained the racor and turned the engine
over and it filled so it seems that fuel pump is working.

I had changed the fuel filters late last summer. I figured that perhaps I
had picked up some sediment do to the fuel sloshing around in the tank. I
changed both filters( they did not seem overly contaminated) and bled the
engine and it ran fine. However the next day the same thing happened. I bled
the fuel filter again and it ran fine. This has happened three times now. So
I am wondering what the problem is.

When I bleed the engine I normally bleed only the fuel filter (two bleed
plugs) however after reading the manual it advises that to bled the engine
properly you should bleed the fuel pump, filter and injectors. That fact
that I did not do all these could this be the base of my problem. But the
engine ran fine without doing all that.

My son thinks it might be the electric transfer pump. That perhaps it is
injecting air into the system.

Anyway I don't know what steps I should take to correct this situation. Any
thoughts would be appreciated.

While on the Yanmar issue, I get a lot of black residue on the transom. I
thought perhaps I was burring oil but that does not seems to be the case.
Could it be that the injectors need to be adjusted.

Jerry

The 'typical' fuel piping connections on a boat system are 'cheap
compression fitting'. these are subject to releasing their 'grip' over
time. To find a leak in such a system, drain it, then pressurize it
with air at 20 psi and then put soap water on all the joints.... the
bubbles will show where its leaking.
Better to use flare connections on fuel systems.

Injectors can be sent to any Injector Specialty shop for a rebuild;
but, at only 800 hours on the engine yoiu probably have an air leak in
the fuel system. The engine mounted final filter on a 2GM is notorious
for problem with sealing vs. air leak .... consider to change the
gasket.

Black soot on the transom, is a sign of fuel with too small a cetane
rating (try a cetane 'booster' to correct), old degraded fuel - diesel
fuel has a 'shelf life' of only several 'months', an overloaded/lugging
engine due to fouled hull/prop, wrong pitch on the prop, too tight of a
stuffing box (is the box hot to touch when you run?).


In article , Jerry
wrote:

My 1990 Dana has a little over 800 hours on the 2GM20F Yanmar engine. This
summer it got a lot of use and ran well. However, during the last week I
have developed what I assume is fuel feed problem. I started the engine up
and shortly it started to cough . I drained the racor and turned the engine
over and it filled so it seems that fuel pump is working.

I had changed the fuel filters late last summer. I figured that perhaps I
had picked up some sediment do to the fuel sloshing around in the tank. I
changed both filters( they did not seem overly contaminated) and bled the
engine and it ran fine. However the next day the same thing happened. I bled
the fuel filter again and it ran fine. This has happened three times now. So
I am wondering what the problem is.

When I bleed the engine I normally bleed only the fuel filter (two bleed
plugs) however after reading the manual it advises that to bled the engine
properly you should bleed the fuel pump, filter and injectors. That fact
that I did not do all these could this be the base of my problem. But the
engine ran fine without doing all that.

My son thinks it might be the electric transfer pump. That perhaps it is
injecting air into the system.

Anyway I don't know what steps I should take to correct this situation. Any
thoughts would be appreciated.

While on the Yanmar issue, I get a lot of black residue on the transom. I
thought perhaps I was burring oil but that does not seems to be the case.
Could it be that the injectors need to be adjusted.

Jerry