97 GTX Will not run high RPM's

[Truckshop21]

Afternoon,

So first off I'm pretty good with mechanical stuff but don't know much about ski's. My ski is having an issue where it will not run higher then around 1500-2000 RPM's on trailer. I've already replaced fuel filter and voltage regulator and no change. I even cleaned one of the RAVE valves and still the same.

So here are some other symptoms. The small I think 5amp fuse in the gray box kept blowing and never knew why. Finally was frustrated and replaced it with a 10amp and it's been fine. The key doesn't always beep when first plugged in. Also seems like I might have a short cause if the ski sits for over a week the battery is usually dead.

Any help from y'all would be appreciated.

 

[Coastiejoe]

You need to find your electrical gremlin...

The larger fuse is an indication that you have an issue. That along with the battery going dead in short order.

If you have a wire that is partially grounded for example, it can seriously affect the performance of the MPEM. If it were my ski, I would remove every hot and ground wire I could find, clean the ends and check the cables for condition. Any white powder near the ends means the wire is junk (internal corrosion).

I would also run a few new ground wires as the ground is often am issue.

 

[Truckshop21]

Ok sounds like I have a lot of wires to check. Can I also use a meter on the ohm setting and put a connector at each end to check for a short. If so what should the reading be on a bad wire

 

[gtx787]

Oh and when these are out of water they should be idling at 3000 rpms and in water is 1200-1500

 

[Truckshop21]

Well I charge the battery and clean the battery terminals then I noticed the little black wire going to the black box for the coils next to the battery was corroded so I put a new terminal on that and it fired up and red dolly up and ran fine. Then I let it sit for 15 minutes Came back and now it won't start. It will crank and its backfires but won't run. The only thing I did different was I had the gray box apart up front and after I shut it down I put the gray box back together and then it wouldn't start. What could be causing it to crank and backfire but not start? Could it be a wire in the gray box.

 

[1983]

Pull that gray box back apart ( battery disconnected ) and see if wire got pinched in the gray box halves upon reassembly. Pull apart slow and inspect all around for suspect wire. One could be caught causing your issue.




Rob

 

[Truckshop21]

No pinched wire found.

 

[Truckshop21]

Any ideas???

 

[wfo speedracer]

Cranking and backfiring are usually one of four things, fouled plugs , a weak battery ,a sheared flywheel key or a sheared brass gear on the rotary valve shaft, it goes without saying start with the battery and spark plugs first.

Next recharge the battery, then take the grey box back apart remove the red wire going to the rectifier-regulator , try to start the ski, does it crank over and run properly now, if it does the rectifier is bad, leave it unplugged for a few days and see if it starts again or if the battery is dead, it can both cause running problems and bleed voltage off the battery when it goes bad.

 

[Truckshop21]

Ok I will check the battery and spark plugs. I just replaced the rectifier as I also thought that was the problem.

 

[soccerdad]

I would still pull the rectifier wire for the test.

It could be the MPEM. My GSX uses the 97 MPEM. I had a starting issue where it would crank and eventually backfire REALLY loud. (a pipe backfire, not a carb one). After tons of troubleshooting I tried a different MPEM. That solved it immediatly. The 97 MPEM has the CDI built in and that was the problem. The other MPEM functions worked but the CDI was the issue. Here is the tread. The solution was on the last page. http://www.seadooforum.com/showthread.php?68737-96-gsx-not-starting-need-some-tips/page3

 

[Truckshop21]

Well you called it I left the battery on a two amp charger overnight and sure thing the ski fired right up. Now I'm just curious if my battery is bad, or if the ski is just not charging the battery correctly

 

[1983]

Connect a voltmeter to positive and negative terminals of battery while its running and tell us what the voltage is. Then you can get an idea what the rectifier/stator is doing. Voltage should be higher while running than while at rest, and that is how you know charging system is doing something. But you don't want excessive voltage such as 15-17 volts, that would mean rectifier is bad. ( doubtful though since you just replaced ) Did you use an OEM seadoo rectifier or an aftermarket replacement?




Rob

 

[Truckshop21]

I used an aftermarket one. Even though I was hesitant. Seems to be running awesome now. Getting ready to sell it for $1500 w/trailer.