T-Roy
Member
I bought a basket case Challenger last year because the deal seemed right and I've owned enough Seadoos to typically fix most anything wrong with them. I've met my match with this one, though.
The boat came with one SBT engine with just a few hours on it and one blown one. I replaced the bad one with a matching 787 from SBT. The boat started and ran, but it had serious cavitation issues, so I rebuilt both pumps with new impellors. First outing two weeks ago, it ran like a champ. Came out of the water great, topped out great - no issues until the very end of the day when it started to bog down and wouldn't go above 4000 or so. Figured I fouled the plugs or something and headed back to the ramp. Put new plugs in it and tried again. Same thing, bogs down and neither motor will go past 5000, however, it did rev up and plane out for a short distance. But, as soon as I throttled down and tried to take off again, I was back to 5000 and plowing. Plugs are very wet when I look at them. It doesn't appear to be over-oily, so I'm confident that the oil system and fuel delivery is fine. When they are running at 5000, I can throttle back from full to 2/3 before they start responding, so I'm pretty sure at WOT, the wet plugs are from the excess fuel.
I checked the obvious at the lake before hanging my head in defeat and putting it back on the trailer. Once home, I dug in a little deeper to see if anything stuck out. I did find one RAVE valve that has to be inop since the valve and the bellows are not joined together and the valve moves up and down freely. The other seems OK and not stuck as well as the two in the other motor. Obviously, an issue for that motor.
Second thing I found was the metal band around the bellows in the opposing engines water pressure regulator was missing the screw and was not compressing. I located the screw in the bottom of the valve and put it back together. Again, obviously an issue, but I'm questioning if that would cause any real issues as the bellows and spring are fine.
Third, one the motor with the bad RAVE valve, I found a small split in the coupler between the pipe and muffler. I could hear water dripping and finally figured out it was draining out of there.
This boat has been giving us fits with the DESS where the rubber cap seems to be worn out and will not stay on the post. It will partially dislodge and kill the motors. Irritating, but if you hold your tongue just right when you put it on, it will stay.
So, the only thing I can see that would prevent ONE engine from running right would be the RAVE valve on the starboard engine. For the life of me, I cannot figure out what is preventing the other one from going past 5000 and why this happened rather suddenly.
My plan is to repair the bad valve and clean the rest of them to take that part out of the equation. The water regulator has been repaired. I plan on ordering a new DESS so I don't have to fight with that stupid thing anymore as well as a new coupler between the pipe and muffler.
The rev limiter works when in neutral at 3500, so I don't think the switch is bad. Both carbs were clean and rebuilt when I put the motors in. I've had it out approximately 10-15 hours since then.
So, with the one bad RAVE, which will not allow the starboard engine to properly run out, will that cause the port engine to also not run out? Too much load for it to get past that point? I've read thread after thread where it could be rectifiers, water regulators, etc., but what could be causing the same reaction out of both motors? The only thing I can think of that is in common with both motors is the MPEM and even then they should react independently from what I understand.
Any help or advice would be appreciated, I'm really stumped on this one.
The boat came with one SBT engine with just a few hours on it and one blown one. I replaced the bad one with a matching 787 from SBT. The boat started and ran, but it had serious cavitation issues, so I rebuilt both pumps with new impellors. First outing two weeks ago, it ran like a champ. Came out of the water great, topped out great - no issues until the very end of the day when it started to bog down and wouldn't go above 4000 or so. Figured I fouled the plugs or something and headed back to the ramp. Put new plugs in it and tried again. Same thing, bogs down and neither motor will go past 5000, however, it did rev up and plane out for a short distance. But, as soon as I throttled down and tried to take off again, I was back to 5000 and plowing. Plugs are very wet when I look at them. It doesn't appear to be over-oily, so I'm confident that the oil system and fuel delivery is fine. When they are running at 5000, I can throttle back from full to 2/3 before they start responding, so I'm pretty sure at WOT, the wet plugs are from the excess fuel.
I checked the obvious at the lake before hanging my head in defeat and putting it back on the trailer. Once home, I dug in a little deeper to see if anything stuck out. I did find one RAVE valve that has to be inop since the valve and the bellows are not joined together and the valve moves up and down freely. The other seems OK and not stuck as well as the two in the other motor. Obviously, an issue for that motor.
Second thing I found was the metal band around the bellows in the opposing engines water pressure regulator was missing the screw and was not compressing. I located the screw in the bottom of the valve and put it back together. Again, obviously an issue, but I'm questioning if that would cause any real issues as the bellows and spring are fine.
Third, one the motor with the bad RAVE valve, I found a small split in the coupler between the pipe and muffler. I could hear water dripping and finally figured out it was draining out of there.
This boat has been giving us fits with the DESS where the rubber cap seems to be worn out and will not stay on the post. It will partially dislodge and kill the motors. Irritating, but if you hold your tongue just right when you put it on, it will stay.
So, the only thing I can see that would prevent ONE engine from running right would be the RAVE valve on the starboard engine. For the life of me, I cannot figure out what is preventing the other one from going past 5000 and why this happened rather suddenly.
My plan is to repair the bad valve and clean the rest of them to take that part out of the equation. The water regulator has been repaired. I plan on ordering a new DESS so I don't have to fight with that stupid thing anymore as well as a new coupler between the pipe and muffler.
The rev limiter works when in neutral at 3500, so I don't think the switch is bad. Both carbs were clean and rebuilt when I put the motors in. I've had it out approximately 10-15 hours since then.
So, with the one bad RAVE, which will not allow the starboard engine to properly run out, will that cause the port engine to also not run out? Too much load for it to get past that point? I've read thread after thread where it could be rectifiers, water regulators, etc., but what could be causing the same reaction out of both motors? The only thing I can think of that is in common with both motors is the MPEM and even then they should react independently from what I understand.
Any help or advice would be appreciated, I'm really stumped on this one.
