jbizub5192
New member
Hi Everyone,
Im working on a 01 Merc 50 2 stroke. It was a neighbors boat which sat for about 7 years. The engine has only around 100 hours on it if that. It was just bought and used for 1 season before it sat. Its having an odd issue I cant figure out. When its cold you can get it up on plane and go full throttle. After about 15 secs running full throttle it will start to surge and each surge reduces the overall rpm. Eventually after a few minutes you will be back down to around 3k rpm. This boat does not have a tach but having worked on many outboards in the past I fell its around 3k. Just enough to lift the bow up a decent amount. Everyday I can repeat this same pattern like clockwork.
I've already rebuilt the carbs, rebuilt fuel pump, new filter, fuel lines, primer bulb, new tank, new plugs. I really dont know what else it could be. Once it gets to the point where the rpms are severely reduced the only way to keep it running is backing down the throttle. If I try to go to full it will stall. However, with that said I also tried to manually pump the fuel bulb to see if that would increase the rpms and it does not. No difference. I pushed the electronic primer and that only made it slightly worse. So its getting fuel that's not the issue.
It seems to me there is something electronic cutting it out. If a sensor is bad would this go into limp mode? Not sure if these engines have a limp mode. Or does this sound like a bad coil pack? Anything else to check? Im going to check compression and timing but I doubt thats the issue. This engine only has 100 hours on it if that.
Thanks,
Justin
Im working on a 01 Merc 50 2 stroke. It was a neighbors boat which sat for about 7 years. The engine has only around 100 hours on it if that. It was just bought and used for 1 season before it sat. Its having an odd issue I cant figure out. When its cold you can get it up on plane and go full throttle. After about 15 secs running full throttle it will start to surge and each surge reduces the overall rpm. Eventually after a few minutes you will be back down to around 3k rpm. This boat does not have a tach but having worked on many outboards in the past I fell its around 3k. Just enough to lift the bow up a decent amount. Everyday I can repeat this same pattern like clockwork.
I've already rebuilt the carbs, rebuilt fuel pump, new filter, fuel lines, primer bulb, new tank, new plugs. I really dont know what else it could be. Once it gets to the point where the rpms are severely reduced the only way to keep it running is backing down the throttle. If I try to go to full it will stall. However, with that said I also tried to manually pump the fuel bulb to see if that would increase the rpms and it does not. No difference. I pushed the electronic primer and that only made it slightly worse. So its getting fuel that's not the issue.
It seems to me there is something electronic cutting it out. If a sensor is bad would this go into limp mode? Not sure if these engines have a limp mode. Or does this sound like a bad coil pack? Anything else to check? Im going to check compression and timing but I doubt thats the issue. This engine only has 100 hours on it if that.
Thanks,
Justin