98 Speedster-Help

[Oljoe]

I have a 98 seadoo Speedster with twin 787’s. Both motors run great, the problem I have now is if I start the starboard motor then start the port the starboard will die. It doesn’t kill it while cranking only when the port motor starts. If I start the port first the starboard motor will hit and die. I have checked all the fuses, grounds, connectors. Unplugged the rectifiers. Changed starter buttons and the DESS post. Changed batteries. I am at a loss any ideas??

 

[Mainah]

Just a few questions to get you thinking based on known issues. Has the boat had a premix conversion? If not have you changed the well known problematic oil lines? Have you changed out the fuel lines which can also become problematic. Have you checked the fuel selector valve? how about the fuel filters. Before all of that determining if the issue is fuel/oil vs spark is a good idea.

It is rather odd that the starboard motor dies only after the port fully fires. My questions above are based upon what you have already done and with the assumption that with a backed up fuel or oil system and possibly out of tune carbs, bad rave valves, etc. that one is starting the other for something on the fuel/oil side. Again determining if spark or fuel is the first thing if you have not already.

 

[Oljoe]

It’s getting plenty of fuel, it’s robbing the spark. I can start the P motor then start the S motor, the Port motor dies but if I immediately kill the S motor the P will fire back up and run. Thinking it has to be something electrical it I’m just not sure. I hate to think it’s the Mpem but I’m starting to lean that direction. It just has me puzzled that they both run fine just not together.

 

[Mainah]

Yep sounds like electrical gremlins. I never had to spend much time on the electrical side of the seadoo 2 smokes I owned. Wish I could offer more help but really hard to say what is going on with this and it sounds like you know what you are doing. Hopfully it won’t require a new box.

 

[Oljoe]

Thanks for your input, hoping something will just trigger something new to look into. I’ll take any ideas anyone has, so thanks again.