I have a 50 HP 4JH engine which is suffering about a 30-40% loss of
power. I cleaned the fuel, changed the Racor and the engine filter,
and cleaned the fuel injectors. THe engine will run up to 3500 RPM in
neutral but in forward or reverse only about to 1500 RPM, thus I am
only getting about 25 or 30 HP, if that.

A new high pressure fuel injection pump costs about $1500 or I could
have it rebuilt for about $800. One thing is that the manual
lever-operated fuel transfer pump which hangs off the side of the high
pressure pump does not work. I installed an electric fuel transfer
pump. The final fuel filter is a non-Yanmar filter. I am going to
bypass it just to see if I am getting a high presure drop across it
when I need a higher flow rate.

One other possibility is that the transmission is bad. I got salt
water in it twice via the external salt water oil cooler, but there is
no way to check it that I know of. I installed a clear plastic tube
on the return line from the cooler so I can see what color the fluid
is. (Salt water turns the oil the color of Pepto Bismal - pink and it
froths).

I am on my boat on a remote Colombian island called Isla San Andres,
about 200 miles north of Colon, Panama. Parts are imposible to get
here. I am considering sailing the boat to Colon where I can get any
parts I need. It might be a good idea to rebuild the transmission
first to see if that is the problem. My son is looking into a rebuild
kit and service manual for a Borg-Warner velvet drive transmission
model number 1017014. He can send it to me in Panama. Everything that
is sent to this island goes through customs in Bogota and is held up
for 2 to 3 months, thus the reason to sail the boat to Panama. It is a
down hill two-day run there with a good following sea and a beam reach
all the way, so I will not need all 50 HP.

I have traded some e-mails with the Yanamr service tech at Mstry
Engione Center in St. Pete, FL but not much help (basically sent it
back for a rebuild is the response).

Any help would be appreciated.

Jerry Poore
S/V Pelleas
Isla San Andres, Colombia