Just wondering

[TradeMark 1564]

I just recently brought a 1997 Sea Doo speedster with twin 787's and was wondering why whoever owned it last would've by-passed the MPEM to start the left engine?....If I start the right then the left will start no problem but upon taking a closer inspection I saw that they cut the left start button wire at the first junction and ran two new wires. I followed the new wires and I saw they go to the Electric box where they are directly hooked up to the cellenoid......Odd but it works, only problem is I can't start the left engine without starting the right first.....Very Weird....well anyway I'm new to the forum and thanks for any replies.....Also what is the best type of battery to use as the previous owner had a car battery in there....Boat works so I'm happy, just puzzled.

 

[Dr Honda]

Your boat has 720 engines, not 787's.


The MPEM is actually what starts the engines, and the button on the dash is asking the MPEM to do so. (That same button becomes the stop button while the engine is running)

Sometimes, part of the MPEM will burn out, but the rest continues to function. So... if the start/stop section burnt out on the Left engine, the MPEM may be fooled into allowing it to run, if it sees the tach signal from the right engine. (just a guess)


I will say this... since the MPEM has a known problem with the start/stop for the left engine... I would be very careful to make sure that that engine isn't over reving. The rev-limiter is part of that function, and if it is also not working, jumping out of a wave at full throttle, could be death to that engine.


The reason why.... it's because the price tag of the MPEM for you boat is about $1500, and, they are hard to find.

 

[TradeMark 1564]

Thank You

I was thinking the same exact thing....thank you for your reply....the rev limiter links up through the same start wire or you're thinking if theres a problem with the left it may be a deeper routed with the mpem ?....well i thank ou very much for your reply and on a side note was wondering what's the best type of battery to use? where would i even find a replacement mpem?

 

[TradeMark 1564]

also

Is the rev limiter reading from the right engine then also??....think i should go to a gas oil mix?? what is the rev limiter?

 

[TradeMark 1564]

I just tried shut of switch

yeah that must be it.....i hit stop button and it went to engage the starter again......so are the rest of the components still reading from the left engine? everything else is hooked up except for the start......ahhh i guess time'll tell.....thanks for the reply Mr. Honda

 

[mikweb]

TradeMark 1564

I am having that same problem and would like to know exactly where the 2 wires connect to and from. I would like to try this before I spend $1800 for a new mpem. please help, thanks.

mikweb@yahoo.com

 

[Dr Honda]

TradeMark 1564

I am having that same problem and would like to know exactly where the 2 wires connect to and from. I would like to try this before I spend $1800 for a new mpem. please help, thanks.

mikweb@yahoo.com

A few things....

1) I put a response in your other thread... so go read it there.

2) This is an old thread (2.5 years) and if you notice that member only has a few posts to his name. He hasn't logged on in a very long time. It's typical for people to get an answer, and never come back. So... before pulling up an old thread... please continue on yours.


With that said... if you see an old thread from a current member... you are welcome to pull it up again.


Lastly... for other people reading this... you can't bypass an 800 or 951 engine. But... you can bypass a 720 and smaller, carb'ed engine.