I took my 1986 Johnson 100hp Comm out for a test run with mixed results. The
timing linkage came apart then the fuel line slipped off at the connection
to the motor. Once all that was straightened out the motor popped the boat
right out of the water and up to WOT rpms of 5000 with grins all around.
Then the motor all but stopped cold and was hard to turn over. With a little
begging it started again and we limped back to the dock as the motor
wouldn't pick up speed at all. The next day I took it out minus the cheering
section (two stepsons) and it ran the same just bogging down when the
throttle was increased. Trying not to make too many changes at once and
remembering that every time I messed with the sparkplugs it ran better I
took the boat out and put new plug wires on it as the new spark plugs were
on the way but won't be in until tomorrow.

Taking the boat out again without messing with the spark plugs and the new
wires on it did the same thing just bogging down when the throttle was
applied. I limped back to the dock and pulled two plugs on the starboard
side just cleaning them off with a paper towel. After putting the plugs back
in the motor it idled better so I took it out and the performance that I'd
seen before was there for a couple hundred yards then it was back to the
bogged down motor again, could it foul the plugs that fast?

I rebuilt the carbs, new thermostats, new water pump, new Holley "blue" fuel
pump with a regulator set at 5 psi to replace the VRO and a 50:1 fuel mix in
the tank. I have Champion L77CJ4 in the motor right now and NGK BUHXW-1
surface gap plugs on the way which I hope will solve the problem. Could an
improper setting on the floats cause such a problem as I didn't have the OMC
gage to set them up with? Would anyone have the specks on that gage for the
100 hp Comm?

Thanks Mick

Better run a compression test. The first stop incident sounds suspicious.
may have ring and/or cylinder wall problems.

--
Ron White
Boat building web address is
www.concentric.net/~knotreel

Yup.

-W

"Ron White" wrote in message
...
Better run a compression test. The first stop incident sounds suspicious.
may have ring and/or cylinder wall problems.

--
Ron White
Boat building web address is
www.concentric.net/~knotreel

That was checked and it was an even 110 on all four cylinders but the motor
hadn't been run for a couple years. The motor came off of a 20 ft Boston
Whaler now it's on a 16' Thunderbird trihull could it be that the high speed
jets are too big for the lighter load?

Mick

"Ron White" wrote in message
...
Better run a compression test. The first stop incident sounds suspicious.
may have ring and/or cylinder wall problems.

--
Ron White
Boat building web address is
www.concentric.net/~knotreel

"Mickey" wrote in message
news:Gkjlc.9337$A27.2420@fed1read06...

I rebuilt the carbs, new thermostats, new water pump, new Holley "blue"
fuel
pump with a regulator set at 5 psi to replace the VRO and a 50:1 fuel mix
in
the tank.

Do you have the VRO wiring completely removed from the pump?
If not, the built-in low oil safety feature may be sensing low oil flow and
restricting the motor's rpm's

"Ron White" wrote
... Better run a compression test. The first stop incident sounds
suspicious.
may have ring and/or cylinder wall problems.


"Mickey" wrote
That was checked and it was an even 110 on all four cylinders but the
motor
hadn't been run for a couple years. The motor came off of a 20 ft Boston
Whaler now it's on a 16' Thunderbird trihull could it be that the high
speed
jets are too big for the lighter load?

Mick

It's a little unclear, but I think you're saying that you checked it
sometime before you took it out the other day? I think Ron's referrring to
the incident that you described on the water - where the motor stopped and
then was hard to turn over. The compression might have been fine when you
checked it, but might not be now. Worth checking again, anyway.

Cam

I wish it was that simple Joe yes the pump is removed and the alarm circuit
from the tank has been removed also. I put the NGK spark plugs in only to
have the motor idle rough still. I did check the new plugs after running it
in the driveway for a while and had the two on the starboard side were
discolored a little but the ones on the port side were clean. I fumbled with
my manual checking a couple things with an ohm meter not finding anything in
particular wrong. I did have one plug on the bottom port side that was
spotless clean so I thought it wasn't firing. I swapped coils on that side
but it still did the same thing. I need to look into the stator and power
packs next but really can't afford to replace everything. I checked the
powerpack for a bad diode that looked good. Could a bad stator or pickup be
causing this and be this erratic? As it stands right now the motor is idling
rough at 800 rpm which is a sign that it won't run well out on the water. I
have to start my 4 graveyard shifts now so it will be a couple days before I
can get back at this thing unless it keeps me from sleeping.

Mick


"Joe" wrote in message
...

"Mickey" wrote in message
news:Gkjlc.9337$A27.2420@fed1read06...

I rebuilt the carbs, new thermostats, new water pump, new Holley "blue"
fuel
pump with a regulator set at 5 psi to replace the VRO and a 50:1 fuel
mix
in
the tank.

Do you have the VRO wiring completely removed from the pump?
If not, the built-in low oil safety feature may be sensing low oil flow
and
restricting the motor's rpm's