Hello, I recently bought a 1997 Sea doo Sportster. The boat seems to operate fine until about half throttle at which point the engines rev and the boat begins to take off, but the then it stalls out and the RPM's drop off. If you leave the throttle in position the motor will again begin to rev and take off, but then the RPM's drop off. It almost feels like a slipping transmission. This pattern repeats over and over as long as the throttle is above about half position. Any thoughts?
1997 Sea doo Sportster stalling problems
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I would see if the boat idles fine on the trailer. On the trailer start it, put in forward, and throttle up. If it idles well on the trailer than most likely your motor/carbs are working well. At that point, its probably a problem with the jet pumps not working correctly for several reasons. It could be clogged with debris. maybe not. Also it could be cavitating. First determine how it runs on the trailer. A more specific answer could be found with a little searching here or report what you find.
Dr Honda
Well-Known Member
You can't tell anything on the trailer.
Since you say it feels like a slipping transmission... I would say you have cavitation. Either you have too much clearance in the pump... or the carbon seal is done.
If you go to full throttle... does the engine just rev up to it's red-line, and the boat doesn't go anywhere?
At full throttle (or anything above half throttle) the engine revs, RPM's increase for a few seconds and then it falls off. While the RPM's are high the boat starts to take off, but this doesn't last long as the engine RPM's drop off only after a few seconds. If you leave the throttle in position it will begin to rev again and then fall off. It seems like, but am not sure, that the engine revs as the tide comes back in on the back of the boat.
In response to gcha1727, I did run it on the trailer with a water hose hooked up to it. I manually actuated the throttle at the carburetor with the intake removed. It seemed to rev fine and did not exhibit the rpm drop found while in the water. I did not try this with it in drive however.
In response to gcha1727, I did run it on the trailer with a water hose hooked up to it. I manually actuated the throttle at the carburetor with the intake removed. It seemed to rev fine and did not exhibit the rpm drop found while in the water. I did not try this with it in drive however.
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Not to second guess the good Dr., whose expertise to mine is like a Wake 230 to a kayak. But I had a very similar sounding problem. Changing spark plugs fixed it.
That's a lot easier than a carb cleaning, and a lot less risky too (I lost my choke lever removing a carb, turns out to be a discontinued part which I've had no end of fun locating, finally did). Unless your plugs are relatively new, try that first.
That's a lot easier than a carb cleaning, and a lot less risky too (I lost my choke lever removing a carb, turns out to be a discontinued part which I've had no end of fun locating, finally did). Unless your plugs are relatively new, try that first.
Dr Honda
Well-Known Member
I pulled the plugs after running it on the trailer. They looked to be in good shape the center electrodes didn't look eroded or anything--didn't check the gaps. If memory serves me, they looked a bit wet when I pulled them. Does this help at all? I am not sure where to begin with cleaning the fuels system and carbs. I'm sure I can pull the carbs but have never rebuilt one. I'm not afraid to try new things, but don't want to land myself without a boat at all. Any suggestions?
Plugs are cheap, like $2.50 each. They're right on top, easy as can be to change. Standard spark plug wrench is all that's needed.
Cleaning carbs means removing the throttle and choke cables, also probably replacing the bottom gasket (need to buy online and wait). There are lots of screws and washers. If they haven't been off for a while they could be tough to remove, might strip off a head (happened to me). You're best to have the right sized allen ratchet (I think 8mm? 7mm?), rather than trying to use allen keys. Lots of risk of dropping things irretrievably (in my experience :banghead
under the engine. These bolt styles are hard to find too. Some parts are not even available, I lost the choke lever, it's obsolete and not replaced, so I had to call around a lot. Even worse, dropping something into the intake manifold, you could have a hell of a time getting it out.
Then, when you get the carb off, its bolts could be frozen (mine were), so I had to buy an impact driver. Now carbs have all sorts of tiny bits that the amateur (as you can tell) like me could lose and have trouble figuring out how to reassemble. If you get past all that, wait until you try to re-tension the springs for the throttle and choke levers, and get the oil pump cable correctly re-attached (done by feel alone). I totally tore up my fingers and burned a lot of time with those damn springs. Maybe there's a tool, nobody at my local auto parts store knew of one. If you're a lousy weekend mechanic like me, it's a lot of frustration.
I'd rather work on the drive system, pumps are easy to take off, a lot less parts and if you drop something it falls on the ground, not under the engine.
Of course, if a dirty carb is causing your problem, yes, you should clean, or probably rebuild if you're going to tear the carb apart anyway. I'm just sayin', give new plugs a try. These 2 cycle engines soak the plugs, especially if you're running a little rich they don't seem to last long. Good thing they're cheap.
Cleaning carbs means removing the throttle and choke cables, also probably replacing the bottom gasket (need to buy online and wait). There are lots of screws and washers. If they haven't been off for a while they could be tough to remove, might strip off a head (happened to me). You're best to have the right sized allen ratchet (I think 8mm? 7mm?), rather than trying to use allen keys. Lots of risk of dropping things irretrievably (in my experience :banghead
under the engine. These bolt styles are hard to find too. Some parts are not even available, I lost the choke lever, it's obsolete and not replaced, so I had to call around a lot. Even worse, dropping something into the intake manifold, you could have a hell of a time getting it out.Then, when you get the carb off, its bolts could be frozen (mine were), so I had to buy an impact driver. Now carbs have all sorts of tiny bits that the amateur (as you can tell) like me could lose and have trouble figuring out how to reassemble. If you get past all that, wait until you try to re-tension the springs for the throttle and choke levers, and get the oil pump cable correctly re-attached (done by feel alone). I totally tore up my fingers and burned a lot of time with those damn springs. Maybe there's a tool, nobody at my local auto parts store knew of one. If you're a lousy weekend mechanic like me, it's a lot of frustration.
I'd rather work on the drive system, pumps are easy to take off, a lot less parts and if you drop something it falls on the ground, not under the engine.
Of course, if a dirty carb is causing your problem, yes, you should clean, or probably rebuild if you're going to tear the carb apart anyway. I'm just sayin', give new plugs a try. These 2 cycle engines soak the plugs, especially if you're running a little rich they don't seem to last long. Good thing they're cheap.
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