Challenger won't Rev

[whitehawk1]

Help... Fresh carb rebuild and my 96 Seadoo single motor challenger won't rev up high or go fast. We had a nice steady idle and low RPM's we circle around just fine. WE went to rev it up and go vroom vroom and it got all boggy and the Rpm didn't want to go above 3500-4000.
Any help would be great.

Thanks

 

[Coastiejoe]

Help... Fresh carb rebuild and my 96 Seadoo single motor challenger won't rev up high or go fast. We had a nice steady idle and low RPM's we circle around just fine. WE went to rev it up and go vroom vroom and it got all boggy and the Rpm didn't want to go above 3500-4000.
Any help would be great.

Thanks

Did it rev and then not? If so, was it after it sat for a bit after running for a while?

Pull the rectifier wire and see if it resolves the issue. If so, replace it.

 

[whitehawk1]

no rev at all. No I started before i went to boat ramp. shuter down went to ramp dropped her in and she started right up but never got up into a high
RPM mode. the throttle is responsive for a third and the high end just doesn't ramp up the second ttwo thirds

 

[whitehawk1]

found the recitfier. I read on another thread that I should pull the red wire. I pulled that and it starts now but acts the same. As i watched the rpm's they stopped right at 3500 no higher.

 

[whitehawk1]

Can somebody help me. To pull the rectifier do I just unplug all the wires. I've been looking for a thread to explain"pulling the rectifier wire"

 

[jhjesse]

Are you replacing the rectifier, or are you just testing? To test just unplug the red wire and see if your engine clears up.

Did you set your pop off pressure and check the needle and seat holding pressure when you rebuilt your carbs?
If I am reading your post right, you are idling and getting low speed throttle. If so, I would crack open the high speed screws 1/8 to 1/4 turn and try it if the rectifier is not the problem.

 

[racerxxx]

Does it sound like the video. If it does your neutral safety switch could be bad. See if you can start the boat with the gate lever in forward it reverse. If it starts, the switch is bad. Meaning the MPEM always thinks the gate is in neutral. The switch will be in with the control handle.


Seadoo Jet boat neutral low RPM rev limiter: http://youtu.be/Zoxqd7HMlto

Sent from my SGH-T889 using Tapatalk

 

[whitehawk1]

Thanks for the time, I pulled the red wire and it's the same. I going to try and see if it's the neutral switch tomorrow. Thanks again

 

[whitehawk1]

I am trying the neutral switch tomorrow but can you tell me, can I test out of the water, on the hose? Or does the rev limiter kick on because she's not in big water?

 

[racerxxx]

Like I said, see if it starts in forward or reverse. It should not be able to start in either F or R. If it can then the switch is bad. From there is you remove(lift up) the control handle enough to get to the switch you can ohm the switch with a volt meter. If you got the same reading with the switch open and closed its bad. Be careful removing the control handle assembly, take the 4 screws off the cover plate, then there are 4 more screws, start to work then out and as soon as the move enough spray them with wd-40. Then work them in and out and spray again and repeat the process until you feel comfortable they will come out without binding or breaking. That's the last thing you want..

Sent from my SGH-T889 using Tapatalk

 

[whitehawk1]

Thanks so much for your help. I really appreciate the good people of the forum who've helped me. I tested the rectifier and the neutral switch. Both seem fine. Went through the whole trouble shooting process one more time and saw that the weed remover below was just barely down. The handle was pressed in all the way but the forks were sticky and down a bit. lubed it worked it a few, closed it and My boats running at High RPM's. Sorry for troubling anyone , I'm a newb. but trying to learn. I know I could have fixed that one at the bay with a whole lot less stress, forum involvement, and time. Sorry and Thanks again

 

[ravens9273]

I just went through this. Finally resolved mine (however not a good outcome).

As others have said.

Check the rectifier. This can be one cause
Check Neutral switch. See if boat starts in forward.

My boat was not revving out of the water nor in the water.
The other two issues above were ok with my boat. I then took out the spark plugs. cleaned them and reinstalled. The boat then began to rev finally out of the water normally.
I took boat to the water and still would not rev in the water. Engine cut out every time I put the throttle forward.
I check spark plugs again and they had water. Long story short water is getting into the combustion chamber. This is why it would rev out of water and not in water.
I finally diagnosed my problem but this is the order I would go.

See if engine starts in forward gear. If not move then move on to rectifier.
Others told me to unplug the red wire to rectifier. I did so. see if boat will then rev normal.
Mine did not so it was not rectifier.
I then moved on to spark plugs and was considering redoing carbs again.
Spark plugs were cleaned and this fixed higher rpm's out of water.
I took boat to water and this is where I learned my boat had water leaking into combustion chamber. Water on spark plugs etc...

I am not trying to sound like a know it all. Others here helped me with my problem. The walked me through all the steps. I am sharing with you what I just went through. I tried everything and today I found why my engine would not rev. Sorry to say it was the worst of all issues I could have had.

 

[whitehawk1]

Alright here's a new clue. I started the boat in the yard on the hose it runs great. Took to bay wouldn't rev above the 3500. Brought home put on the hose and it rev up past 5000 just fine. What the heck! It has something to do with water cooling system, right? Anybody know what's bouncing me off the high rims?
Checked neutral switch
Checked rectifier wire

 

[Waterluvr]

You have the same issue I started having with mine today. Everything checks out on my engine ok, good compression and ignition the neutral safety and rectifier aren't the issues and that really only leaves fuel. The only grey fuel lines I have are the 1/4 lines that are on the carb itself, I understand those are known to cause issues.

I'm trying to find a kit to completely rebuild both carbs and the fuel pump and I'll replace those old 1/4 line's while I'm at it, there's really not much else could be wrong at this point.

With your boat making 5K rpm on the hose and 3500 in the water, that sounds about right if you think about your 3K flusher hose idle speed setting that should run at 1500 rpm sitting in the water. Removing the load from the jet pump will show you a big increase in RPM's.

 

[whitehawk1]

Yeah it just seems the rev limiter is bouncing me when I'm in the water. What in the cooling system initiates the rev limiter

 

[Waterluvr]

There's nothing that I know of in the cooling system of the 787 that will bounce you off the rev limiter. Far as I know the only electronic function it has is the ability to ground the sensor wire to the beeper on the helm and alert you to an overheat / no water condition.

 

[whitehawk1]

Just like the rev limiter stops you from reving past 3500 in neutral. Isn't there something with water cooling which doesn't allow higher rpm's. What is the 1/4 line that runs along exhaust?

 

[Waterluvr]

Just like the rev limiter stops you from reving past 3500 in neutral. Isn't there something with water cooling which doesn't allow higher rpm's. What is the 1/4 line that runs along exhaust?

So, I have been looking at every reference I can find for an answer to that question and if someone else knows better please chime in but all I can find are two functions of the control module that will retard ignition.

1. The neutral safety switch/MPEM will limit rpm's to 3500
2. The MPEM will limit engine top end to 7,200 rpm's

I don't have enough experience with these to know if the exhaust / water side are known to have restrictions or regulators that can cause top end issues with these but I would think that would be a slight performance issue of several hundred rpm's and not 3500 of them.

I need to go finish removing the carbs of my Challenger, after thinking about it this morning and giving how well the boat was running until hour number two yesterday and all else checking out I expect to find the two internal carb filters are absolutely filthy dirty with crud.

Or in other words, there's enough fuel getting by to start the boat and run the idle circuits but restricted enough to not allow for any top end operation. This is bad news as lack of fuel + higher rpms = lean condition. For the sake of knowing I am going to pull and clean those filters, install new 1/4 lines and plugs and go for a ride to test the theory while I am waiting for kits to arrive to rebuild them properly.

Now if I could find a complete kit with mounting gaskets etc...