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240 m2 jet drive mercury problems

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iggys6

iggys6

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I replaced the spark plugs in my seadoo today and it was running great on the hose:thumbsup:. I brought it down to the ocean and backed it in, it ran for 4 seconds then shut off, I then noticed how it had no spark after that and I pulled it out of the water and wiggled the battery cables around and the lanyard and it started up on the dry land and then I tried to start it again in the water and it wouldn't. Has anyone seen this problem before? :banghead:
 
There's a thread, a few down, about a problem with a Mercury sentry going bad. It's the unit that watches the RPM when you are in neutral. Read it... it may be your problem.
 
Would that still be the problem if it was running great on the hose? Also I forgot to say I took it out a few days ago for half and hour with the wrong plugs in it and I just found that out today that the old owner put in the 210hp plugs instead. So I picked up the correct 240 plugs.
 
Yes... that's the one I was thinking about.

I don't know if it's your prob or not... but it's something that is easy to check.
 
Okay, Just an hour or so ago I backed it into the water and turned it on, it ran for 2 or 3 minutes and sounded like it was going to shut off so I turned the steering wheel so it would give it some gas and it kept running, right when I turned the wheel back it would run for a minute or so then die. Sometimes it would fire right up and other times it sounded like it was getting no spark so then I unplugged the two black/yellow wires that looks like they lead to the cdms and sometimes it would fire back up with them disconnected and then would shut back off in a few minutes just like what they do when they are connected. I am so confused at this point:confused:
 
OK. It was just something to try. Now, we need to start at the beginning. We need compression numbers... and a fuel pressure number. (there's a fitting at the regulator)

Also... If you just throttle up... will the engine continue to run?
 
My compression last time I checked was 126-127 all cylinders, checked last week. And the fuel pressure number how do I find that on the fitting? Is that what looks like a valve stem? And yes if I throttle up it does continue to run.
 
Yes... it's the thing that looks like a car valve stem.

If it runs when you throttle up... then just turn up the idle a bit.
 
Thats what I did but it sounds like it revs high on the hose but I cannot really tell because my rpm gauge does not work. Also do you just put a gauge on it when its turned on?
 
You need a tach to properly set the idle.

Yes... just put a gauge on the stem, and start the engine. BUT... if it's running up top... then I don't think the fuel pressure is the issue.
 
Okay thanks for your help, I will check tomorrow and tell you after, None of my gauges work so i'm not sure if there is a easy way to see how to fix those but i'm not too interested in that right now I just want it running on the water.
 
Maybe I am way off base here, but when I had the starting issues on my challenger I also noticed the tachometer was dead. It turned out to be a bad voltage regulator.

I'm definitely no expert but just throwing another idea out. Before this was determined I disconnected the throttle guardian as per a sea doo rep that indicated to my mechanic that it was a failure point that was duplicating a function.

Good luck
 
That is what I am thinking too, when I turn on the boat it does not charge itself until I unplug the red wire on the upper voltage regulator and then plug it back in and then it works. I am not sure about the bottom one as on how to test it.
 
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