1998 seadoo sportster 1800 one engine over-speeding to 8000+ RPM’s

[Barnhart501]

I have a problem with my sportster 1800. It has twin 787’s in it; one engine runs great. The other engine will rev to over 8000 rpms as soon as you press the throttle. It actually maxes out the tach. You don’t lose throttle control, because you can bring it back down when you release the throttle. It seems odd that one engine would rev way past the limiter when the other engine runs good. I thought these run on the same rev limiter. I can’t figure out what’s going on. New to the boat, new member to the forum. Thanks for any insights!

 

[POPPS]

Is this on dry land?,,,or in the water?,,,check the throttle cable at the carb,is it binding,,,.are butterflies closed?,,,just take the air box off to look at the butterflies..if everything is okay there,,,perhaps it is binding at the throttle control at the helm
Also,,,had this once,,,in the front cover behind the gauges,,,this jetboat had a linkage from the steering wheel to the throttle cables,,,so that when you are turning and pulling someone,,,tuber etc,,,it maintained the speed,,,check for that first,,,easier to do than checking the carb linkage,

 

[Barnhart501]

Sorry I should have clarified. It is in the water. I had it out again tonight. I manually kept the engines about the same rpm, but it was difficult because one of them was at “half throttle” (but the engine was wound out) and the other was at WOT. I also forgot to mention that it idles perfectly. The throttle response is just way too quick. And I thought the rev limiter shouldn’t even let it go that high?!?!? It was maxing out the tach at over 8K tonight.

I’ll have to check the throttle linkage behind the gauges. Thanks for that tip!

 

[L. Dean Ficarro]

Came across this today, wanted to know what came of the throttle issue. Hope its sorted, cheers!

 

[POPPS]

I would,,,climb down into the hull without shoes on,,,and rev the motor at the carbs by hand,,,amotirwith an air leak will want to rev away on the trailer after you rev it,,,have someone at the choke to snuff the motor if it revs away,,,if it’s not an air leak,,,carb,,,case…it’s a cable/throttle,,from my experience

 

[WhiteZombie]

Is this on dry land?,,,or in the water?,,,check the throttle cable at the carb,is it binding,,,.are butterflies closed?,,,just take the air box off to look at the butterflies..if everything is okay there,,,perhaps it is binding at the throttle control at the helm
Also,,,had this once,,,in the front cover behind the gauges,,,this jetboat had a linkage from the steering wheel to the throttle cables,,,so that when you are turning and pulling someone,,,tuber etc,,,it maintained the speed,,,check for that first,,,easier to do than checking the carb linkage,

Yo Popps. The way you describe the steering assist hooked to the steering wheel- I haven't had it explained that way. I was understanding it to help dock the boat. Mine was unhooked or rattled lose before I got it, so really don't what to expect. I really don't know what to expect at all with this boat once it hits the water.

 

[Barnhart501]

Wow, I haven’t been on the forum for a while and didn’t see any of the 2022 comments lol. So I did figure out my issue last summer. Bad tachometer! Really stupid; I shouldn’t have relied on the gauge, instead I should’ve listened to the hum of the engine. I finally figured it out by buying a manual tach and testing each engine. The engine was working perfectly, just a bad gauge made me think it was faulty. I also swapped out the tachs with each other and verified it that way. Not sure which I did first, it’s been too long lol.