Howdy,
I have a 2010 Yamaha T9.9 GEXH. Three years ago while in use the engine died and I assumed that this was the result of very low fuel so I used the spare fuel jug, which had bad gas in it. (Don’t judge) The engine restarted and then died and wouldn’t restart. I noticed back at the dock that the shifter cable had popped off the shifter arm at the motor.
This engine hung in my garage for three years while I worked to restore the little boat it was mounted to. Now I am looking to restart it. Here is what I’ve done thus far.
Pulled plugs and lubricated before turning over. Replaced spark plugs because the old ones which were pretty new had zero continuity and they were wet with lubricant (not water).
Electric starter worked intermittently, replaced battery cables and brushes. Starter works perfectly. This eliminates there being an issue with the neutral safety switch or the overboard safety switch. The electric starter wouldn’t spin and the engine turn over if I’d forgotten the lanyard or if it was in gear at the remote (it’s not in gear either at the remote or at the prop). (Remote is a 703)
Rebuilt carb. There was some slight varnishing in the bowl and most of the jets were fowled. Carb does spray fuel into the cylinders. No issues with fuel line or pump that I can discern. Replaced fuel with ethanol free fuel.
Changed oil. It actually looked okay, but I did it anyway. Oil level is correct.
Changed gear lube. No issues with water intrusion.
Changed impeller. Drive shaft and shift cam function properly. There was a loose coolant hose that was spraying a very fine mist (no idea how long that’s been going on), which I secured. Water moves correctly, very strong stream through the exit port.
At this point I’m trying to start it. Sprayed starter fluid into the cylinders. Then through the carb. Nothing. It turns but won’t start. Obviously I’m not doing this all at once in a manner which would flood the engine, but in stages and over several days.
Ran compression test, cylinder 1 reads 140psi and 2 reads 145 (I haven’t a clue what they’re supposed to be, but this seems pretty good to me.)
I put an endoscope into the cylinders: I see no scoring along the walls nor do I hear any rings jingling about or feel anything out of the ordinary as it turns over (it also has a pull start). Piston heads look a little gunky, not just carbon, actual gunk that I can scrap off with the camera.
I’m about to pull the ignition coil and check for continuity, (I think this is futile because I can see fuel burning off through the exhaust). I’m wondering two things: Does this motor have some fancy computer in it that might break and cause something weird to happen with an oil/temp sensor, cut off switch, or rectifier? Finally, does this engine have reed valves or something of the sort that can fowl up? I don’t see one on the parts diagram, but then I haven’t started pulling the intake manifold apart yet. (I’d prefer not to)
Frankly, both these questions are ridiculous, I don’t really think that this motor has an ECM, nor do I think reed valves are an issue with fuel in the cylinders and good compression. So if there is anything else I’m missing do tell. What direction would you head in next?
I have a 2010 Yamaha T9.9 GEXH. Three years ago while in use the engine died and I assumed that this was the result of very low fuel so I used the spare fuel jug, which had bad gas in it. (Don’t judge) The engine restarted and then died and wouldn’t restart. I noticed back at the dock that the shifter cable had popped off the shifter arm at the motor.
This engine hung in my garage for three years while I worked to restore the little boat it was mounted to. Now I am looking to restart it. Here is what I’ve done thus far.
Pulled plugs and lubricated before turning over. Replaced spark plugs because the old ones which were pretty new had zero continuity and they were wet with lubricant (not water).
Electric starter worked intermittently, replaced battery cables and brushes. Starter works perfectly. This eliminates there being an issue with the neutral safety switch or the overboard safety switch. The electric starter wouldn’t spin and the engine turn over if I’d forgotten the lanyard or if it was in gear at the remote (it’s not in gear either at the remote or at the prop). (Remote is a 703)
Rebuilt carb. There was some slight varnishing in the bowl and most of the jets were fowled. Carb does spray fuel into the cylinders. No issues with fuel line or pump that I can discern. Replaced fuel with ethanol free fuel.
Changed oil. It actually looked okay, but I did it anyway. Oil level is correct.
Changed gear lube. No issues with water intrusion.
Changed impeller. Drive shaft and shift cam function properly. There was a loose coolant hose that was spraying a very fine mist (no idea how long that’s been going on), which I secured. Water moves correctly, very strong stream through the exit port.
At this point I’m trying to start it. Sprayed starter fluid into the cylinders. Then through the carb. Nothing. It turns but won’t start. Obviously I’m not doing this all at once in a manner which would flood the engine, but in stages and over several days.
Ran compression test, cylinder 1 reads 140psi and 2 reads 145 (I haven’t a clue what they’re supposed to be, but this seems pretty good to me.)
I put an endoscope into the cylinders: I see no scoring along the walls nor do I hear any rings jingling about or feel anything out of the ordinary as it turns over (it also has a pull start). Piston heads look a little gunky, not just carbon, actual gunk that I can scrap off with the camera.
I’m about to pull the ignition coil and check for continuity, (I think this is futile because I can see fuel burning off through the exhaust). I’m wondering two things: Does this motor have some fancy computer in it that might break and cause something weird to happen with an oil/temp sensor, cut off switch, or rectifier? Finally, does this engine have reed valves or something of the sort that can fowl up? I don’t see one on the parts diagram, but then I haven’t started pulling the intake manifold apart yet. (I’d prefer not to)
Frankly, both these questions are ridiculous, I don’t really think that this motor has an ECM, nor do I think reed valves are an issue with fuel in the cylinders and good compression. So if there is anything else I’m missing do tell. What direction would you head in next?