Hello everyone. I have an issue with my engine and was wondering if anyone has an idea what the issue could possibly be? It was running great before sitting for a month and then the next time it was used has trouble running with a load. The moment I started the engine it would run at about 60% for about 4 miles. It runs great under no load but the moment the prop gets in the water it bogs down. I turned off the engine and removed spark plug wires and then reinserted them and it ran fantastic 100% for about 2 minutes and then bogged back down to idle speed. I kept doing this over and over and eventually it just would stay running at idle speed 4 miles back to the boat ramp at about 5% (at least I was able to get back in the middle of the night with no one around . I also noticed that when I would touch the ground wire that connects to the kill switch the engine would run like at 50% but I had to let go because it was shocking me. I also disconnected it to see if that would help and it ran great for about a minute and then bogged back down as I was idling back to the boat ramp. The only thing that I can think of that happened while it sat for a month is that it got heavily rained on one day when a cold front hit.

Get the easy things out of the way first - Start with new fuel, there could be water in your tank from condensation or phase separation from ethanol if your gas is E10 and it will act like this. Check all of your hose connections and tank fittings to make sure there is no air getting in. Look at your fuel line to make sure there are no kinks, or cuts, etc. If you have a new gas tank that is not vented, loosen the cap a little bit to make sure its not vapor locked.

Other things to try - crank her up. While the engine is running, pull one of the spark plug boots off. It should then be running on one cylinder (the cylinder with the boot still connected). Pull the other spark plug boot off while its still running, and it should kill the engine (both plugs now removed). Repeat the process but start with pulling the other cylinder first. You are trying to determine if a coil is bad, or if the engine is only running on one cylinder. If you pull a boot, and the engine dies while the other boot is connected you got a dead cylinder - look at coils and wiring harness.

Thank you for the reply. I did try one with one boot off spark plug and it stayed on but bogged down even worse so i put it back on. The tank was full all the way to the top with nonethanol gas when it rained and the carb was cleaned 2 months ago. It ran like a champ but all of a sudden after that rain something happened. Very strange. Its at the shop now but they are so backed up and said they will get to it soon. I just got to be patient but I’m so fed up with waiting everytime it goes in for a fix or weld fix. I just hope its something minor like spark wires/plugs or something. Thanks for the reply buddy. Frustrating…

Alright, for those interested, after running around with the mechanic for the past couple of months and explaining that the problem seemed to be coming from an arching issue, he changed out the spark wires and coils. Ran like a champ yesterday and hopefully will stay running that way forever. Now need to replace the upper and lower bearings of the shaft since the prop end has some slight wiggle to it. The shaft is also starting to vibrate and creates a banging sound every second while running which has gotten worse just recently. I’m going to do the work myself since I have experience doing the work on my old longtail.

Question??? Since I’m going to do all that work in replacing the bearings, should i go ahead and replace the drive shaft as well? It’s around $200+ (I do not really want to spend the extra cash) but not sure if its absolutely necessary since the shaft has held up for the last 10 outings. I bought this 25hp mudbuddy longtail back in August of 2021 used and the longtail end was in great condition with no rust. The bottom skeg also had no wear. Seems to me this longtail was not really used in harsh conditions. I have no idea how old this motor is but would guess it’s probably around a 2008 or so.