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

Jerry,

I do not know if this may help but there may be a filter on the electric
fuel pump. Mine is a small cylinder on the end of the fuel pump cylinder.

Also I wonder why you would get full revolutions when in neutral and not
when in gear if the transmission is bad.

Sorry I can't help further.

Good Luck

Ansley Sawyer
SV Pacem

On 25 Jun 2004 08:16:00 -0700, (Jerry Poore) wrote:

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
Jerry -

Since you have internet access, check he

http://forums.torresen.com/sailing/

Torresen is the Yanmar distributor in the northeast US. They are
worth 2 of Mastrys, but Yanmar in their wisdom makes me buy from
Mastry. The forum at the link above is excellent.

I'm no expert, but if the engine is failing to reach rpm due to load
issues like a foul prop or a binding tranny, I'd expect to see black
smoke at full throttle. If not, I think it is more likely that you
have a fuel system problem. My 3GM30 behaved like yours when my
electric lift pump bit the dust, FWIW.
__________________________________________________ __________
Glen "Wiley" Wilson usenet1 SPAMNIX at worldwidewiley dot com
To reply, lose the capitals and do the obvious.

Take a look at cpRepeater, my NMEA data integrator, repeater, and
logger at http://www.worldwidewiley.com/

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

To me it sounds like not enough fuel pump pressure. The engine burns more fuel
under load than when freewheeling.

Check your fuel pump, filters and the connections in the hoses for
restrictions. Some trash might be in the fuel hoses. If the Injection pump is
bad usually the engine will miss when freewheeling at WOT.