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jetskigreg
jetskigreg,
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1997 Sea Doo Challenger with a single 787. The boat will

Customer Question

1997 Sea Doo Challenger with a single 787. The boat will only rev to 5000 rpms unless you pump the throttle. The carbs have been rebuilt,and replaced twice. motor replaced, fuel lines replaced, rave valves replaced. I was sure it was fuel related but everything has been replaced or rebuilt several times by 3 different shops. The boat does not always beep when the lanyard is put on but it always starts and idles up to 5000 rpms perfectly.
Submitted: 7 months ago.
Category: Boat
Expert:  jetskigreg replied 7 months ago.

I believe u have bad regulator rectifier u might have to do on the water but get a digital multimeter put on DC volt setting start it up and run for a bit and see how many volts show up on meter also rev it and verify voltage if at any point wether idle or reved u have over 14 volts u have a bad regulator rectifer let me know these readings and i will tell u where to find

Customer: replied 7 months ago.

I will let you know the readings as soon as I get the boat out again. I have done the test where you disconnect the red wire to the rectifier before with no help however.

Customer: replied 7 months ago.

I checked the voltage and maximum was just over 14 volts. I replaced the rectifier anyway with no improvement. I disconnected the red wire, also no help. After about 45 minutes it won't go past 5000 rpms even if you pump the throttle.

Expert:  jetskigreg replied 7 months ago.

Can you unhook the neutral safety switch in where your throttle stck is this is the only thing i know that would limit engine power beside a carb problem if this is not it you probably need a new stator the lightning coil has probably went bad on stator

Customer: replied 7 months ago.

I will do that this week. How can I check the stator? Since it gets worse after it has been run for about an hour I think the stator might be the culprit. The carbs have been rebuilt twice then replaced, the accelerator pump rebuilt and replaced. the fuel lines are new, I even used a fuel bottle and a direct feed to the carbs.

Customer: replied 6 months ago.

I replaced the stator and still no change. I have seen on the internet others who have this problem but no answers. Surely someone knows how to fix this. The motor revs fine out of the water but only revs to 5000 rpms when in the water. If you blip the throttle hard it will rev to 7000. After about an hour of run time even this will not work. The carbs have been rebuilt and then replaced. I used a fuel bottle and ran fuel directly to the carbs. I even replaced the motor with no help. Could it be the water box? I am about ready to part this thing out! Sadly it is too nice. Always garage kept, new interior,etc.

Expert:  jetskigreg replied 6 months ago.

It can be the waterbox but i need you to check one other thing that you said in your last response that you had not said previously you said if you nail the throttle it will work for a short time i need you to check your throttle cable and make sure throttle plates are all the way open u will have to remove flame arrestor and open throttle all way up with throttle lever then grab the throttle linkage on carb and pull make sure it is opening all way up. If that has a Y throttle cable and one cable goes to oil pump and somebody removes oil pump you have to tape cable that went to oil pump up or it will slack your carb cable and not let it go all the way open or if someone didnt properly seat oil pump cable in its place it will also give it slack let me know

Customer: replied 6 months ago.

Thanks, ***** ***** checked the throttle cable lately. but it does rev to 7000 out of the water with no problem. I will check it this weekend.

Customer: replied 6 months ago.

By the way I am rebuilding the rave valves next week just to be on the safe side.

Expert:  jetskigreg replied 6 months ago.

Keep in mind it really doesnt matter what it does out of water because with any kind of pull on the motor a quater throttle is almost wide open out of the water its like a car runnin on 3 cylinders out of gear runs decent but when you put in gear it wont hardly move

Customer: replied 6 months ago.

I checked the throttle cable and rebuilt the rave valves. I just came back from the river and still have the same problem. One thing I noticed today is that when you make a large sweeping turn the boat drops off plane and stays at 3000 rpms. sometimes you have to pump the throttle several times to get back up on plane. Once it decides to rev it runs perfect.

Customer: replied 6 months ago.

Im still waiting on help. Please reply.

Expert:  jetskigreg replied 6 months ago.

I am not 100 percent sure but u have a cable problem if that happens when u turn ur throttle cable is the problem u can check it too open the lid where the steering wheel is there is 2 cables that attach to the back of steering column the biggest cable is ur steering cable and the small cable is throttle either your cable is broke where it Y's back at the throttle or up in front on column but it has a cable problem. From the factory that thing was made when u turn to give the boat throttle so it would turn quicker if it breaks at the Y the cable internally does not have enough tension part number###-##-####i dont know if it still available most of the parts on that boat have been discontinued but you can try sbtontheweb carries a lot of those cables that have been discontinued

Customer: replied 6 months ago.

It does it when in a straight line or turning. I have looked down the carbs while on the water. They are wide open. The odd thing is that it always goes to the same rpm before it levels out. which is just below 5k. its not hitting a rev limiter. It simply will not rev any higher unless you pump the throttle.

Customer: replied 6 months ago.

I just took the water pressure apart and it appears to be ok. I blew in the water inlet and covered the other holes and it moved freely. there has not been any water leaking around the regulator.

Expert:  jetskigreg replied 6 months ago.

There is only 3 things then u either have an air leak (crank seal) somewhere , rotary valve timing is off the rave valves only come into play above 6000 rpm or you have an exhaust blockage the only other thing i have seen is a customer brought me one with a similar issue and come to find out the owner before him had plugs made to put in the outlets of the exhaust pipe for winter time so things couldnt build nest in there and by shear dumb luck he found it on his own.

Customer: replied 6 months ago.

Its probably not the crank seal. the boat has had 2 motors with the same problem and usually if a crank seal goes it revs to the moon. I will check the rotary valve timing again but I don't think dropping the rpms and pumping the throttle would make any difference if that was the issue. I know this is not a simple fix. It has been to three shops to repair this problem. Thats why it has had 3 carb rebuilds and one new set of carbs. The general consensus has been carbs or rave valves. The rave valves have been rebuilt before but I just replaced them again just to be sure.

Expert:  jetskigreg replied 6 months ago.

I agree with crank seal i also agree i dont think it is timing you dont have another mpem you could try do u?

Customer: replied 6 months ago.

I don't and its about the only thing left that has not been replaced. I did talk to one of the guys that rebuilds the mpem's and he didn't think that was the problem. However everything else seems to check out. Do you know if anybody else has solved this problem by replacing the mpem? It's pricey but I don't know what else it could be. I am a pretty good home mechanic but this thing has stumped me as well as the pros.

Expert:  jetskigreg replied 6 months ago.

No i do not know of that being a problem on the boats but i have seen on jet skis seadoosource dot com sells kits to convert it to a regular jet ski mpem however he will not talk to you by phone only email but a good person to know if you know what i mean

Customer: replied 6 months ago.

I think I will email them. Thanks, Doug

Expert:  jetskigreg replied 6 months ago.

sounds great let me know if I can help

Expert:  jetskigreg replied 6 months ago.

Thank You

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