I have a 1989 Mariner 60HP 2-cycle outboard. Three cylinders. Two carburetors.
It starts and idles ok in neutral, and if I advance the throttle in neutrals, it revs up fine (not sure of the RPMs).
But when I put it in gear, it dies.
The motor seemed to run ok when the previous owner demonstrated it before I bought it, and ran ok in gear at high throttle for a few minutes after I installed it on my pontoon. It killed when I tried to run at idle, and after that I was able to run it in gear for a couple minutes, but now can’t get it to run in gear.
Compression seems ok to me:
Top: 110 psi
Middle: 115 psi
Bottom: 119 psi
Fuel pump seems to work fine, and I replaced the fuel filter.
There is spark on all three plugs, though it’s hard to tell if it’s as strong on all three. All plugs are new.
If either the bottom plug or middle plug wires are disconnected, the motor seems to start and run about the same as when all three are connected. If the top plug wire is disconnected, it won’t start.
When I spray carburetor cleaner or Mercury Power Tune in the top carburetor while idling, the motor bogs down and kills.
When I spray carburetor cleaner or Mercury Power Tune in the bottom carburetor while idling, it doesn’t have any effect on the sound/RPM of the motor.
I held a piece of paper in front of the carburetors, one at a time, while the motor was running at fast idle. Both carburetors sucked the paper tight, but the top one seems like it might have sucked it a little tighter. Hard to say for sure. When the paper sucks tight against the top carburetor, the motor bogs down. When the paper sucks tight against the bottom carburetor, the motor pitch doesn’t change.
I tried a spark plug test light, but couldn’t see it light up for any of the cylinders, maybe because the light was too bright.
If I connect a jumper wire to the exposed high voltage metal on this tester and bring it close to the motor chassis, I get these results:
Bottom cylinder—sparks jumped air gap of ~1/4” to 1/2”. There was no effect on the motor running when the wire was shorted to the chassis.
Middle cylinder—same as bottom cylinder
Top cylinder—Spark doesn’t seem to jump as much of an air gap as for the middle and bottom cylinders, but when shorted to chassis, the engine kills.
I removed the bottom carburetor and disassembled and cleaned most of it with carburetor cleaner, spraying cleaner through all of the orifices. The motor seemed to start and idle in neutral about the same with the bottom carburetor removed, as with it installed. After replacing it, the motor seemed to start and run the same in neutral, but still won’t run in gear.
Any ideas what could be causing this?
It starts and idles ok in neutral, and if I advance the throttle in neutrals, it revs up fine (not sure of the RPMs).
But when I put it in gear, it dies.
The motor seemed to run ok when the previous owner demonstrated it before I bought it, and ran ok in gear at high throttle for a few minutes after I installed it on my pontoon. It killed when I tried to run at idle, and after that I was able to run it in gear for a couple minutes, but now can’t get it to run in gear.
Compression seems ok to me:
Top: 110 psi
Middle: 115 psi
Bottom: 119 psi
Fuel pump seems to work fine, and I replaced the fuel filter.
There is spark on all three plugs, though it’s hard to tell if it’s as strong on all three. All plugs are new.
If either the bottom plug or middle plug wires are disconnected, the motor seems to start and run about the same as when all three are connected. If the top plug wire is disconnected, it won’t start.
When I spray carburetor cleaner or Mercury Power Tune in the top carburetor while idling, the motor bogs down and kills.
When I spray carburetor cleaner or Mercury Power Tune in the bottom carburetor while idling, it doesn’t have any effect on the sound/RPM of the motor.
I held a piece of paper in front of the carburetors, one at a time, while the motor was running at fast idle. Both carburetors sucked the paper tight, but the top one seems like it might have sucked it a little tighter. Hard to say for sure. When the paper sucks tight against the top carburetor, the motor bogs down. When the paper sucks tight against the bottom carburetor, the motor pitch doesn’t change.
I tried a spark plug test light, but couldn’t see it light up for any of the cylinders, maybe because the light was too bright.
If I connect a jumper wire to the exposed high voltage metal on this tester and bring it close to the motor chassis, I get these results:
Bottom cylinder—sparks jumped air gap of ~1/4” to 1/2”. There was no effect on the motor running when the wire was shorted to the chassis.
Middle cylinder—same as bottom cylinder
Top cylinder—Spark doesn’t seem to jump as much of an air gap as for the middle and bottom cylinders, but when shorted to chassis, the engine kills.
I removed the bottom carburetor and disassembled and cleaned most of it with carburetor cleaner, spraying cleaner through all of the orifices. The motor seemed to start and idle in neutral about the same with the bottom carburetor removed, as with it installed. After replacing it, the motor seemed to start and run the same in neutral, but still won’t run in gear.
Any ideas what could be causing this?
