Motor info:
2003 Mercury 2.5hp Model #1002201AK
(I believe these motors are built by Tohatsu for both Mercury and Nissan)
Problem:
Outboard will no longer start, occasionally backfires
History of Problem:
I purchased this motor along with a 15ft RIB in 2019. The 2.5HP serves as an emergency 'kicker' in case my 40.0HP Yamaha has problems when out on the water as I'm in a remote location in the Pacific.
I generally store the boat out of the water on a trailer; after each weekend I usually run both my main outboard and this 2.5HP outboard in fresh water for a few minutes to get rid of salt deposits, etc. I've never needed the 2.5HP for an emergency and generally don't use it, so running it every weekend keeps it running well and will alert me if it's not working. I mention this for 2 reasons: first, this 2.5HP motor has barely been used so it is in almost new condition for internal parts; second, this motor always started without any issues until the following.
Although the motor always started and ran well, very soon after my purchase I noticed that water was neither coming out with the exhaust nor flowing out of the indicator hose/hole. Although this wasn't an immediate issue since I always only ran the motor for a few minutes, I knew it would be a problem if I actually needed the motor in an emergency. Eventually I got around to tackling it, and after replacing the pump impeller without any change or improvement, I discovered the cooling lines were completely clogged with sediment/corrosion/gunk.
I spent a week or two slowly working the cooling system clean using vinegar to dissolve the deposits in the cooling passageways. The vinegar worked well at clearing out the lines and eventually water flowed freely through the cooling system when I rinsed water through it. However, when I built it back up, the engine would not start.
It was soon clear that I hadn't been careful enough with the vinegar and had corroded the wires going to the ignition coil (not the spark plug wire, but the wire from the CD unit and the ground wire). Replacing the ignition coil seemed like a simple fix but didn't solve the problem. I next replaced the CD unit, the spark plug, and finally the exciter coil inside the flywheel (these being the complete electrical system for this motor). The engine still wouldn't start. Occasionally it would behave like it wanted to start (would turn over more than usual with one pull) and once in a while it would backfire.
I verified my spark by taking the spark plug out and grounding it to the motor housing while turning the engine over. The spark looks good (bluish) to my untrained eye. So I figured maybe the problem was with the carburetor. Even though inspection showed it looking clean, I replaced it with a new carburetor since it didn't cost much. With the new carb, the engine still won't start.
Conclusion:
I'm now at a loss of how to proceed. Someone suggested checking the compression. With my thumb on the spark plug hole, it feels like it's getting compression, but I'm not sure what to compare it to. I'm now waiting on a compression gauge from someone I know. The way it backfires also suggests to me that it is a timing issue. However, there is no way to change the timing on these motors (that I see). They are very simple. I even checked to see if I put the flywheel back on incorrectly, but there's only one way for it to go on the shaft (no possibility of installing it 180deg out) and the key is in good shape (so the flywheel is not slipping on the shaft).
Anyone have any other ideas? This is starting to drive me nuts.
2003 Mercury 2.5hp Model #1002201AK
(I believe these motors are built by Tohatsu for both Mercury and Nissan)
Problem:
Outboard will no longer start, occasionally backfires
History of Problem:
I purchased this motor along with a 15ft RIB in 2019. The 2.5HP serves as an emergency 'kicker' in case my 40.0HP Yamaha has problems when out on the water as I'm in a remote location in the Pacific.
I generally store the boat out of the water on a trailer; after each weekend I usually run both my main outboard and this 2.5HP outboard in fresh water for a few minutes to get rid of salt deposits, etc. I've never needed the 2.5HP for an emergency and generally don't use it, so running it every weekend keeps it running well and will alert me if it's not working. I mention this for 2 reasons: first, this 2.5HP motor has barely been used so it is in almost new condition for internal parts; second, this motor always started without any issues until the following.
Although the motor always started and ran well, very soon after my purchase I noticed that water was neither coming out with the exhaust nor flowing out of the indicator hose/hole. Although this wasn't an immediate issue since I always only ran the motor for a few minutes, I knew it would be a problem if I actually needed the motor in an emergency. Eventually I got around to tackling it, and after replacing the pump impeller without any change or improvement, I discovered the cooling lines were completely clogged with sediment/corrosion/gunk.
I spent a week or two slowly working the cooling system clean using vinegar to dissolve the deposits in the cooling passageways. The vinegar worked well at clearing out the lines and eventually water flowed freely through the cooling system when I rinsed water through it. However, when I built it back up, the engine would not start.
It was soon clear that I hadn't been careful enough with the vinegar and had corroded the wires going to the ignition coil (not the spark plug wire, but the wire from the CD unit and the ground wire). Replacing the ignition coil seemed like a simple fix but didn't solve the problem. I next replaced the CD unit, the spark plug, and finally the exciter coil inside the flywheel (these being the complete electrical system for this motor). The engine still wouldn't start. Occasionally it would behave like it wanted to start (would turn over more than usual with one pull) and once in a while it would backfire.
I verified my spark by taking the spark plug out and grounding it to the motor housing while turning the engine over. The spark looks good (bluish) to my untrained eye. So I figured maybe the problem was with the carburetor. Even though inspection showed it looking clean, I replaced it with a new carburetor since it didn't cost much. With the new carb, the engine still won't start.
Conclusion:
I'm now at a loss of how to proceed. Someone suggested checking the compression. With my thumb on the spark plug hole, it feels like it's getting compression, but I'm not sure what to compare it to. I'm now waiting on a compression gauge from someone I know. The way it backfires also suggests to me that it is a timing issue. However, there is no way to change the timing on these motors (that I see). They are very simple. I even checked to see if I put the flywheel back on incorrectly, but there's only one way for it to go on the shaft (no possibility of installing it 180deg out) and the key is in good shape (so the flywheel is not slipping on the shaft).
Anyone have any other ideas? This is starting to drive me nuts.
