1996 XP 787 Bogging: carbs and rectifier checked.

[zachu812]

Got a 1996 Seadoo XP 787 with a "locked up engine", found a fuel tank strap jammed up in the PTO so I pulled it out and verified the crank seal was still good. Took the ski for a ride, little boggy so I was careful with it but it ran great in short bursts. I rebuilt the carbs on it with genuine Mikuni kits, set everything to spec, pop-off pressure at 30psi. While the carbs were off I was poking around the electrical system and noticed the fuse for the VTS was gone, threw one back in and the VTS unit started smoking when I hooked the key up. Pulled the fuse back out and the jet-ski wouldn't beep anymore so I pulled the front electrical box and noticed a blown 5A fuse on the MPEM, replaced that and everything was good. Before I was done I noticed the classic leaky pipe plug so I poked around to get all the junk out and put some JB weld on (it'll get fixed right once it runs good). Put it in the water and had a great strong idle, starts super easy, but when you give it more than 1/4 throttle all it does is bog. Pulling the choke makes it stall almost immediately, makes me think it's running rich. Everything I checked is listed below. Is it possible I fried something in the MPEM? Can I swap the carbs off my good running 1997 XP 787 to verify it's not a fuel issue? Could poking a hole in the pipe plug send too much water in the exhaust? I did my diligence to check the common problem areas, anything new to try or check would be appreciated. I'd swap whatever I can off my 97 if that helps.

-Pulled carbs apart again to verify popoff pressure and correct diaphragm placement
-All new fuel lines, verified good fuel flow when cranking
-Unplugged rectifier and tested with same results
-Good fresh battery and clean terminals
-New spark plugs and clipped wires

 

[harleytq]

Sounds exactly like what mine did, with a bad rectifier. You say you disconnected the red wire, from rectifier? And it still did the same?

 

[zachu812]

Sounds exactly like what mine did, with a bad rectifier. You say you disconnected the red wire, from rectifier? And it still did the same?

correct, same result.

 

[RG123]

Try increasing the pop off to 38. I had the same problems on my 787 GTX and that solved the problem.

 

[fatblockabody]

Check exhaust hose for soft spots. Does it bog on the trailer, no load?

 

[zachu812]

Try increasing the pop off to 38. I had the same problems on my 787 GTX and that solved the problem.

I'll give that a shot, thanks for the suggestion!

Check exhaust hose for soft spots. Does it bog on the trailer, no load?

Will do. If you snap the throttle open it has a slight bog with no load but opening it slower the ski revs right up.

 

[zachu812]

Try increasing the pop off to 38. I had the same problems on my 787 GTX and that solved the problem.

Just put in the correct black Mikuni springs, runs the same unfortunately.

Sounds like fuel deprivation,,,either fuel selector/(baffle pickup,,,rare),,. or carub circuits.

I don't think this is a fuel deprivation issue, pulling the choke makes it worse so the ski is running rich while bogging.