97 1800 Sea Doo Challenger won't plane out

[sls0866]

Help! Just bought a 97 Sea Doo Challenger with twin 110's ran great for 2 trips. The 3rd trip started to notice it didn't want to turn too quickly like it was bogging down when you tried to corner. On the 4th I ran it out of fuel due to a broken fuel gauge and every since boat will not run correctly. Starts fine, RPM's are there but the boat will not come up on plane. Comes out the hole great never bogs down but acts as if there's 5000 pounds of weight in the stern. Could this be an impeller issue? Thoughts?

 

[Ronnie]

No experience with those engines (787 cc, 2 stroke 2 cylinders) in a boat but plenty with them in seadoo skis. I suspect that it's a fuel delivery problem like a bad on / off valve (on the skis the wax breaks down over time the part is easy to replace on the skis and cheap at $20 or less) and /or gummed up fuel lines (the fix is to replace them, cheap but time consuming). At least that is what it was when I had similar issues, could be time to rebuild the carbs as well (they have a small fuel filter in them which gets clogged from time to time) unless your boat is fuel injected. Consider looking at the green hulk site which is dedicated to pwcs.

 

[Mainah]

I had the same boat and rebuilt both engines and all 4 carbs last year. First off that could be a lot of different things. Since it was running fine and the changing point was running out of fuel then you may have gotten water in your engines from being towed. The other common things to look for is debris in the pumps even small stuff, impeller clearance, impeller condition, fuel valves, fuel filters, spark plugs, rave valves, carbs and proper amount of grease in the output shaft bearings. If you are hanging around 5k rpms on one engine then once on plane it kicks in then most likely the rave vales need cleaned or replaced. The carbs have 3 adjustments total, low, and high. If it takes off fine and the rave valves and slots are clean and in good order than you may be lean or rich on the high side assuming the internal of the carbs are all good. If you rebuild the carbs only use the stock jet sizes which are different for the boats than the skis and only use genuine mikuni parts. I also think Greenhulk will be better site for you to get info on the 787 rotax engines. All of that said below is the order I would start checking things.

If you got towed in a greater than 5 mph without the engines running than you most likely have water in your engines. If saltwater than a rebuild may be in order at this point. If you know what you are doing than deal with this yourself otherwise a well established jet ski and snowmobile shop may be the best bet. Check the pumps and impellers for anything visible. Replace the plugs with the proper ones gapped to spec (NGK BR8ES I think). While at it do a compression test and look for at least 140 psi in each cylinder with the cylinders no more than 3 psi apart on the same block. Anything under 140 psi or same block cylinders more than 3 psi apart and you are getting close to internal engine component failure. Now take her out and see if that has solved anything. If that did not next would be pulling the rave valves and see how much carbon they have caked on and how worn they are along with inspecting the boots for tears (have replacement gaskets available when you do this). Also pull the fuel valves and blow some air though them to make sure they are working good and replace the fuel filters at the same time. If no issues found confirm operation after putting back together and dive into the carbs but only if you have experience with that. A jet ski or snowmobile shop that has been around for a while will have plenty of experience with these engines and the carbs. Just make sure they look at the boat manual for the proper initial jet sizes and adjustments as they ARE different than the skis and sleds that use the same engines and carbs.

Good luck and welcome to the site