My 1996 Johnson 88 spl has started a severe miss that prevents the engine from even idling at normal idle speed. It will idle at a fast idle. If I rev the engine the miss does not go away, so I have not tried to take the boat out. The miss is very consistent, every second or two, with a distinct puff through the exhaust. I identified the cylinder with the miss by pulling plug wires one by one until miss went away. I then swapped this plug wire and coil with another and the miss stayed with the same cylinder, so don't think the coil or wires are the issue. I then replaced the plugs and then the Power Pack. This did not solve the issue. What else would cause such a miss?
A little history - the boat is recently new to me. When purchased it ran fine, other than it seemed to require slightly more throttle than fast idle to start when cold (even using enrichment key press), and it is not very cold here in Florida, lol. Once it started it ran fine. I could run for as long as I wanted at less than 4500rpms and not overheat, but it would overheat if stayed near 5000 or more for more than a couple of minutes. So I didn't run it more than 4500rpms. I then replaced the water pump and this seems to have solved the overheating at higher rpms. After changing the pump I took the boat out for a test run and after warming it up I stayed at WOT, around 5200rpms, for a few minutes to test and it did not overheat. I went back in happy. The next day I took the boat out and could hear an occasional miss after I was out for a bit and it slowly got worse. The boat died as I shifted to reverse when pulling up to the dock and was hard to restart and had the consistent miss. Haven't taken it out since (a few days ago).
A little about me (my first post) - This is my first boat of my own. I have owned some older PWC's and have dove into various things on those and rebuilt one of those engines. (Yamaha 1200 npv.) I'm a car guy and general all around diy kind of guy and not afraid to work on anything. I'm new to boat engines, but figure they are still an engine.
I'm guessing the issue is now carb related, but not sure where to begin diagnosing this on this boat engine, and curious what would cause it to suddenly develop. The boat was driven on the lake at least every other or third day or more and have had no issues or hint of a miss until right after I replaced water pump. I don't see how replacing water pump would be related, but I think maybe the run at 5200rpms for extended test may be related to development of miss, but not sure exactly how since this shouldn't be an issue. But since I hadn't done that before due to overheating (and previous owner said he stayed around 4000rpm), I'm suspicious of that, but may just be purely coincidence that the miss started now.
Thanks in advance for any assistance,
Ray
A little history - the boat is recently new to me. When purchased it ran fine, other than it seemed to require slightly more throttle than fast idle to start when cold (even using enrichment key press), and it is not very cold here in Florida, lol. Once it started it ran fine. I could run for as long as I wanted at less than 4500rpms and not overheat, but it would overheat if stayed near 5000 or more for more than a couple of minutes. So I didn't run it more than 4500rpms. I then replaced the water pump and this seems to have solved the overheating at higher rpms. After changing the pump I took the boat out for a test run and after warming it up I stayed at WOT, around 5200rpms, for a few minutes to test and it did not overheat. I went back in happy. The next day I took the boat out and could hear an occasional miss after I was out for a bit and it slowly got worse. The boat died as I shifted to reverse when pulling up to the dock and was hard to restart and had the consistent miss. Haven't taken it out since (a few days ago).
A little about me (my first post) - This is my first boat of my own. I have owned some older PWC's and have dove into various things on those and rebuilt one of those engines. (Yamaha 1200 npv.) I'm a car guy and general all around diy kind of guy and not afraid to work on anything. I'm new to boat engines, but figure they are still an engine.
I'm guessing the issue is now carb related, but not sure where to begin diagnosing this on this boat engine, and curious what would cause it to suddenly develop. The boat was driven on the lake at least every other or third day or more and have had no issues or hint of a miss until right after I replaced water pump. I don't see how replacing water pump would be related, but I think maybe the run at 5200rpms for extended test may be related to development of miss, but not sure exactly how since this shouldn't be an issue. But since I hadn't done that before due to overheating (and previous owner said he stayed around 4000rpm), I'm suspicious of that, but may just be purely coincidence that the miss started now.
Thanks in advance for any assistance,
Ray
