Seadoo 787 Timing/carb jet issue?

[jwebb246]

I have a 1996 787 motor installed in a aluminum boat and I was having issues with the motor last year so I bought a complete motor and buddy installed it as I was out of town for a few months. For the most part the boat runs amazing but some times it only revs up to 4700rpms and if I mess with the throttle and ever so slightly pull the choke it'll pick up and run great for 5-20 min and then do the same thing. When the motor was installed he just put the motor in and didn't do anything with the timing so I'm wondering if that could be an issue. But with the choke thing I'm thinking it may need a different jet size? It starts and idles fine every time. I will only have one day to wrench on it when i get back in town and am hoping its something simple? Any help is greatly appreciated!!

I don't know if the previous motor was rebuilt or if the current one is either so I'm thinking if one was bored out bigger it may not have the correct jet sizing in the carbs?

 

[mikidymac]

Carbs are running lean if pulling the choke helps.
Did you rebuild them with genuine mikuni parts?

 

[jwebb246]

The carbs haven't been rebuilt, I could try that though. The 12V low constantly flashes so I'll probably order a rectifier as well. What's weird is that if you pull the choke to much it'll bog way down, but if you just barely pull it'll go to full rpm's.

 

[Ckrawiec]

The carbs haven't been rebuilt, I could try that though. The 12V low constantly flashes so I'll probably order a rectifier as well. What's weird is that if you pull the choke to much it'll bog way down, but if you just barely pull it'll go to full rpm's.

Well, before you go off and replace the rectifier....do a simple test.....measure the voltage on the RED wire out of the rectifier (with motor running).....it should be somewhere around 13.5 VDC....if so, the rectifier is fine.

I THINK I've been chasing my own 12V low problem all wrong....my version of the '96 GTX has the integrated CDI in the MPEM (called a MAAP on my wiring diagram - I'm using a '97 diagram which matches my ski)....anyway, the wiring diagram shows the rectifier RED going into the MAAP and 2 Red/purple coming out of the MAAP...one R/p goes back to the Solenoid side of the battery connection (so this would keep the battery voltage up to snuff), the other R/p goes to the Infocenter (and I assume this is the signal wire that IF IT IS NOT above 12.6/7 VDC then the 12V LOW message gets activated - depending on what the 12V low threshold is of course).

So, if the MAAP is not putting out 13.5+ VDC back to the battery....then the MAAP is faulty I would therefore assume and it would not be the rectifier as the problem (related to the 12V low issue).