Good morning, everybody. Wanted to share my saga here, and the fix that was completely unexpected.
I have a 2004 Mercury 150hp 2-stroke carbureted on a 2004 Angler 21 foot walkaround. I've had the boat 8 full seasons and it's always been a really dependable boat and motor.
In may of 2026, I had a "Spring Service" done by a mobile mechanic. Plugs, filters, oil/water separator, impeller, thermostats. Pretty basic. I launched the boat for the first time this season the next day.
I backed off the trailer at the ramp and maneuvered to my slip, but decided to take it out for a shakedown cruise. Headed through 12 minutes of no-wake zone, and the boat was running great...nice and cool...last season I was running hot due to degraded thermostats and impeller, but now, with the service, all good.
Got out of the no-wake zone and accelerated up to 20mph in forward until I reached deeper water, then decided I'd check all my systems (radio, washdown, livewell, etc.) Went to put the boat in neutral, but it was stuck in forward gear. RPM's were high, and the slowest I could get was about 8mph. I drove around in circles for a few minutes trying to figure out what to do. I was afraid to shut the motor off, thinking I wouldn't be able to start it if it didn't get into neutral.
I called the marina and made sure my trailer was still at the ramp and in the water. Figured I'd have to maneuver through a tight marina at 7.5mph and aim for the trailer then shut it off. I only made it back about 100 yards, then the motor sounded like it was trying to shift (grinding gears) and high rpm. I panicked and shut the motor down. I was in a very shallow rocky area so I threw an anchor and called for TowBoat. Got towed back to the marina and pulled the boat out.
The next day the same mechanic stopped by the marina to have a quick look (he had another job lined up) and he said the boat seemed to be shifting fine. He sent me a video clip of the shift selector moving properly when he moved the controller at the helm. He suggested the shift cable may have a bind in it somewhere.
I spent 600 dollars and had both shift and throttle cables replaced with new OEM cables, and the control box inspected. Mechanic said control box was good. They tested it (on muffs) and said it was shifting fine.
Launched the boat 2 days later and had the same issue. Once in forward gear for a bit, tried to shift into neutral...stuck in forward at 8mph. Got towed back in. Deja Vu.
Next mechanic (different place....the "experts") diagnosed issue as a high idle. They adjusted the idle and said all was good, and that was the only issue. Another $600 to get this information.
Launched the boat the next day. All was good...for about an hour. Then it was stuck in forward gear, same high rpms, 8mph was the slowest I could do. I shut it off. This time it wouldn't start again....it would pop and run for two seconds at very high idle and die. Got towed back in. Took it back to the supposed experts.
The "experts" said they were going to have to pull the power head and look at the shift rod, thinking the original mechanic may have bent it when reinstalling the lower unit. They said it was going to be costly. Luckily, I had seen some YT videos from an outboard rebuilding shop in Connecticut, and the guy knows all things 2-stroke. I called him, and he said to get the boat from the experts and bring it to him.
Trailered it up to him yesterday. He pulled the upper cowl off and saw that my throttle plate was open. He touched it and it popped back down (closed.) Then he saw that the oil injection arm (that links the throttle to the oil pump) was installed in the wrong position. It hadn't been rotated against the spring so that the "lines" match up. This had the arm at the wrong angle to the throttle plate, causing the throttle plate to get stuck open. This created the high RPM's preventing the motor from shifting out of forward gear.
Apparently after the issues I've been having, the throttle plate would pop back down and all would seem good, but once in forward for a bit, the torque applied by the oil injector arm against it would hold it open, causing the high rpms. I also noticed that the engine was smoking a lot at idle and started hard. This is because I was getting "full oil" (50:1) even at idle, since the oil pump boss wasn't being properly adjusted by the arm/throttle link.
This awesome mechanic popped the arm off, rotated the oil pump boss to the proper position (lined up the marks) and popped the arm back on. I took the boat to the ramp across the street and ran it on the trailer for 40 minutes, shifting in and out of gear, throttling up in forward, etc. No issues. Much less smoke at idle.
I have been searching forums since May and haven't found one person who had the same issue. I'm creating this post just so it might pop up if somebody else has the same issue in the future.
For the life of me, I can't imagine why the original "Spring Service" mechanic would have removed that arm from the oil pump. He did change the inline filter which is close, but he says he didn't do it. I had the carbs serviced a few years ago, but I would think this issue would have happened after that...I guess it may just be coincidence that it happened the day after the service was done. Either way, I'm glad somebody finally figured it out.
I have a 2004 Mercury 150hp 2-stroke carbureted on a 2004 Angler 21 foot walkaround. I've had the boat 8 full seasons and it's always been a really dependable boat and motor.
In may of 2026, I had a "Spring Service" done by a mobile mechanic. Plugs, filters, oil/water separator, impeller, thermostats. Pretty basic. I launched the boat for the first time this season the next day.
I backed off the trailer at the ramp and maneuvered to my slip, but decided to take it out for a shakedown cruise. Headed through 12 minutes of no-wake zone, and the boat was running great...nice and cool...last season I was running hot due to degraded thermostats and impeller, but now, with the service, all good.
Got out of the no-wake zone and accelerated up to 20mph in forward until I reached deeper water, then decided I'd check all my systems (radio, washdown, livewell, etc.) Went to put the boat in neutral, but it was stuck in forward gear. RPM's were high, and the slowest I could get was about 8mph. I drove around in circles for a few minutes trying to figure out what to do. I was afraid to shut the motor off, thinking I wouldn't be able to start it if it didn't get into neutral.
I called the marina and made sure my trailer was still at the ramp and in the water. Figured I'd have to maneuver through a tight marina at 7.5mph and aim for the trailer then shut it off. I only made it back about 100 yards, then the motor sounded like it was trying to shift (grinding gears) and high rpm. I panicked and shut the motor down. I was in a very shallow rocky area so I threw an anchor and called for TowBoat. Got towed back to the marina and pulled the boat out.
The next day the same mechanic stopped by the marina to have a quick look (he had another job lined up) and he said the boat seemed to be shifting fine. He sent me a video clip of the shift selector moving properly when he moved the controller at the helm. He suggested the shift cable may have a bind in it somewhere.
I spent 600 dollars and had both shift and throttle cables replaced with new OEM cables, and the control box inspected. Mechanic said control box was good. They tested it (on muffs) and said it was shifting fine.
Launched the boat 2 days later and had the same issue. Once in forward gear for a bit, tried to shift into neutral...stuck in forward at 8mph. Got towed back in. Deja Vu.
Next mechanic (different place....the "experts") diagnosed issue as a high idle. They adjusted the idle and said all was good, and that was the only issue. Another $600 to get this information.
Launched the boat the next day. All was good...for about an hour. Then it was stuck in forward gear, same high rpms, 8mph was the slowest I could do. I shut it off. This time it wouldn't start again....it would pop and run for two seconds at very high idle and die. Got towed back in. Took it back to the supposed experts.
The "experts" said they were going to have to pull the power head and look at the shift rod, thinking the original mechanic may have bent it when reinstalling the lower unit. They said it was going to be costly. Luckily, I had seen some YT videos from an outboard rebuilding shop in Connecticut, and the guy knows all things 2-stroke. I called him, and he said to get the boat from the experts and bring it to him.
Trailered it up to him yesterday. He pulled the upper cowl off and saw that my throttle plate was open. He touched it and it popped back down (closed.) Then he saw that the oil injection arm (that links the throttle to the oil pump) was installed in the wrong position. It hadn't been rotated against the spring so that the "lines" match up. This had the arm at the wrong angle to the throttle plate, causing the throttle plate to get stuck open. This created the high RPM's preventing the motor from shifting out of forward gear.
Apparently after the issues I've been having, the throttle plate would pop back down and all would seem good, but once in forward for a bit, the torque applied by the oil injector arm against it would hold it open, causing the high rpms. I also noticed that the engine was smoking a lot at idle and started hard. This is because I was getting "full oil" (50:1) even at idle, since the oil pump boss wasn't being properly adjusted by the arm/throttle link.
This awesome mechanic popped the arm off, rotated the oil pump boss to the proper position (lined up the marks) and popped the arm back on. I took the boat to the ramp across the street and ran it on the trailer for 40 minutes, shifting in and out of gear, throttling up in forward, etc. No issues. Much less smoke at idle.
I have been searching forums since May and haven't found one person who had the same issue. I'm creating this post just so it might pop up if somebody else has the same issue in the future.
For the life of me, I can't imagine why the original "Spring Service" mechanic would have removed that arm from the oil pump. He did change the inline filter which is close, but he says he didn't do it. I had the carbs serviced a few years ago, but I would think this issue would have happened after that...I guess it may just be coincidence that it happened the day after the service was done. Either way, I'm glad somebody finally figured it out.