RESTO sea-doo will not rev over 3300rpms

[crundell73]

I have a sea-doo jet boat with the 787 engine in it , I just cleaned the trigger and stator and cap from shavings put it back together and had a huge backfire, starts and idles fine but will run really ruff at 3300 rpms and will not go any higher , unhooked the red wire same thing , plugs are wet looking and exhaust is hot with water hooked up ! any ideas ?

 

[racerxxx]

Just out of curiosity, you do have the control handle in the forward position correct? It could be the neutral start switch. If you can start the boat in forward or reverse that will tel you it's not working properly.



Does it sound like this?


[video=youtube;Zoxqd7HMlto]https://www.youtube.com/watch?v=Zoxqd7HMlto[/video]

 

[crundell73]

I don't know if it is hooked up because I replaced the mpems with jet ski computers ! it was not doing this before I cleaned the stator , but I can check that just in case . Thank you .

It sounds close to that but more backfire !

 

[racerxxx]

If you used 2 ski MPEM's then the NSS is out of the circuit.

Are these OEM or aftermarket MPEM's?

 

[crundell73]

the engine that I'am Having trouble with is aftermarket mpem that is new, dose not need a programed key for the dss any key works , but i tried the OEM, mpem and did the same thing !

 

[racerxxx]

Who helped you wire in the MPEM? You might want to ask them if there is other hardware in the loop.

 

[crundell73]

I did it all my self ! was very careful switching the wires and have the wiring specs for the boat and the ski ,
But I got the backfire from switching a few wires one time , but i can get the one engine to run great all the time and before cleaning the stator and replacing the mpem with a new aftermarket one, before that they would both run great till the mpem blow out that 5amp fuse .

 

[racerxxx]

So you replaced one of the MPEM's with an aftermarket one that USED to be an OEM one, is that correct? If so, there have been several aftermarket MPEM's right out of the gate that were bad. We just had a member go thru this on a ski.

 

[crundell73]

yes i did but i used one from the other engine that is working right and it dose the same thing ? cause that is what i was thinking too . but who knows lol

 

[racerxxx]

Well then, if the ONLY thing you have done is the stator repair/cleaning you know where you need to go and look. Look at the bracket when you tear it apart, the early ones were prone to cracking.

 

[crundell73]

The Bracket that holds the trigger? I cleaned the trigger and had it apart think I could of done anything to that ?

(The only other thing I did at the same time was change the fuel filters and they were both defective , don't know if that would cause anything and could the key on the fly wheel shear you think ? ) Thanks for your help ...

 

[racerxxx]

Nah, I've had them apart numerous times. They will fall right back into place on a 787. Did you tighten it? Did you have the mag cup off the flywheel? Did you clean the mag cup of metal shavings? Cut the spark plug wires back a 1/4" or so and screw the boots back on.


Just to rule out the MPEM's have you put the aftermarket one on the good running engine?

 

[crundell73]

the book said you can through the timing off if you remove the stator or trigger , what you think of the key shearing , I can take the mpem from the other engine and try it again but I did it before and it sounded the same , I hope it is not the mpem !

 

[racerxxx]

The stator and trigger are fixed on a 787. You'd need to really screw something up to throw off the timing. The portion of the manual you're referring to is probably a 720 or smaller engine that has an adjustable stator plate. I guess it's possible that you could shear the woodruf key. But you'll need to tear the flywheel out of it to check.

Sent from my SGH-T889 using Tapatalk

 

[crundell73]

I never thought of the other engines , but I know it includes all three in the book , I bet your right ! so that takes me down to the key or mpem , The carbs would not cause it to sound like it is out of time ?

 

[racerxxx]

The only other thing it could be is the rotary valve gear stripped or jumped throwing off the rotary valve timing. For that you would need to look in thru the carbs and see if the rotary valve disc is rotating. Or, look at the oil in the line to see if you see brass bits. Perhaps I missed it but what exactly prompted you to clean the trigger? I mean, you just don't go in and clean that as regular maintenance so something had to have happened to direct you there.

 

[crundell73]

it was a blowing my mpem had metal shavings and the trigger had some rust on it so I cleaned it up

 

[crundell73]

update , Got the engine back in and it runs great / had metal savings on my stator trigger and cap, cleaned that and took me so long to figure that out that when I put the engine in the first time the gas went bad , new gas and it sounds Great ! The other engine also had metal shavings and I think that was the cause of my 6degree advanced timing will have to check that and was getting hot ! Have to test it all more ! make sure it all holds up!