95 Speedster one engine won’t stay running

[Mckleroy]

So my dad bought this boat new back in ‘95 (657x engines). I have now acquired it from my uncle who had it for a few years also. So my problem is that the port (left) engine will run great for about 5-10 minutes and then just shut off. No sputter, no misfire, just gone. It’s also hard to restart until it cools off. So the backstory is when I got the boat I had to do a top end on the left engine because it gaulded the front piston. He knocked an oil line off while changing batteries and didn’t know it, crank looked good and rods didn’t have excessive play so I put a set of std pistons back in it and honed the cylinders. Engine also didn’t have any spark (before the rebuild) so I replaced the coil with a Chinese unit. Also replaced the one mpem with dual mpem’s since the port mpem fuse was blowing.

So to summarize how this has gone, Stbd engine is fine, port engine didn’t run, replaced coil for port engine and both mpem’s, port engine runs for 10 minutes and dies no warning, rebuilt port engine because of low compression, with the new top end compression is now 150, port engine still dies after 10 minutes. Spark plugs were new but are now chocolate brown so it’s not lean or a fuel problem (I don’t think) Just put two new props in it because of cavitation and was hoping that was causing overheating. Apparently that wasn’t it but it needed it anyway. So now I’m thinking it’s the Chinese coil unless someone can give me any more suggestions.

 

[emspjay]

Are the new MPEM's also aftermarket Chinese along with the coil? Many people have reported problems with those aftermarket MPEM's. Hard restart when warm is normally caused by worn needle and seats in the carb.

 

[Mckleroy]

I also went through the carbs on the port engine, forgot to add that. Everything looked great, the filters were clean. The grey fuel line for the pulse was plugged, that has been replaced. Yes the mpem’s are aftermarket which means that they are 99% sure from China.

 

[emspjay]

Replace all grey fuel lines, rebuild carbs with genuine Mikuni kits with new needles and seats, get a good used coil and MPEM's from Westside Power sports. Do not waste anymore money on the China parts.

 

[emspjay]

You can also send your original MPEM's to Westside and he can check them and verify if they are good. I recently sent him an 1996 XP MPEM and he verified it was good and then I purchased a new key from him and he programmed it to the MPEM all within a week.

 

[Mckleroy]

The speedster is a one off single mpem that runs both engines. It was for sure bad, one of the capacitors was leaking electrolyte. I’ve got two oem coils ordered. Wish I could find a parts boat but these things are getting rare.

 

[emspjay]

I have been buying parts from Nick for my old stuff for years great guy.

SeaDoo MPEM | Used SeaDoo MPEMs

 

[Mckleroy]

Just wanted to follow up, replaced both coils with used OEM Seadoo coils and it didn’t shut off!! Stay away from the Chinese crap! Hope this helps someone else in the future.