97 GTX dies while riding.

[jemery.wa]

I picked up a 97 GTX that needed work, which seems like it needs 1 of everything! at this point it will run fine in the water on the trailer and will even take off and rip pretty good but it is having a problem of dying after it runs at around 6k for more than 30 sec, sometimes after it dies it won't crank until you remove the key and put it back in. At that point sometimes it will fire right back up and other times it acts like the battery is dead, eventually it will fire up again. when it dies it will just shut off. It happens on both normal and reserve fuel selected. I will list the things that I have done so far.

new top end
oil injection block off kit.
replaced Tempo fuel lines
cleaned out fuel selector, was clogged on reserve side
carbs rebuilt and tested pop off seems to be around 35 and hold pressure
reset screws to factory settings
replaced aftermarket MPEM with another new one (same brand but brand new)
tested DESS post, was fine
tested start button, was fine but seemed to have a 1 sec delay before resistance drops.
tested charging voltage and it checks out good
replaced jet pump, wear ring was installed backwards
replaced drive shaft and carbon seal, driveshaft was partially stripped at PTO due to no grease boot.

I have 2 96 GTXs and even some extra parts for those but the 97 uses a different MPEM so I can't use that to test. My speedometer doesn't work but I believe that is a problem with the speed sensor wire, I found a burn spot in it and neither the analog or digital gauge. The Buzzer doesn't work at all, I do have a spare that I have used when I was trying to reprogram the old MPEM. I will say that even with the new MPEM the rev limiter seems to be set at around 6500 rpm which is low. I have tried with the temp sensor connected and disconnected and it doesn't seem to matter.

I am at a loss of what is going on with this thing.

 

[POPPS]

Fuel selectors cannot be cleaned,,,only replaced,

 

[clegg]

Do you have a Seadoo lanyard key or an aftermarket key?

 

[jemery.wa]

I will bypass the valve altogether to test it although when it died once I rowed to shore and checked to verify there was gas in the filter which there was.

It says Seadoo DESS on it but the aftermarket MPEM doesn't use the DESS wire so any magnetic key works.

 

[1of500]

After market mpems ARE JUNK. SURE SOUNDS LIKE YOU LEAN SEIZED THE ENGINE AT 6K RPM

 

[jemery.wa]

It wasn't the ideal setup to have the aftermarket MPEM but that is what it came with and that is what I could get my hands on.

Could the lean condition caused by low flow through the selector valve or high end carb adjustment? I am thinking it must me the valve.

 

[1of500]

Do a compression test and pull the raves and take a look at the pistons

 

[nibroc]

FULLY AGREE.............

 

[jemery.wa]

compression tested the same as after first run, I am attaching the endoscope pics of the pistons with rave valve.

 

[jemery.wa]

here are some other pics of the pistons

 

[jemery.wa]

The spark plugs are dark but not black

 

[mikidymac]

Hard to tell but it sure looks like bad piston wash.

Pull the rave valves and look into the slot. You will be able to see the sides of the pistons and see if they are scuffed.

 

[jemery.wa]

there looks like some marks on the piston but doesn't look like scoring or metal transfer like I have seen on some pistons I have pulled out before. I am going to bypass the fuel selector and take it out for a test run.

 

[jemery.wa]

took it out, I was able to sustain around 5-5.5k for awhile but as soon as i started getting it over 6k it dies out. Same thing happens, you have to pull the key and reseat it and it may or may not crank. I was riding toward the ramp when it died and it seemed like when you try to throttle it the rpms fall and won't go above 3k for a second and then it dies out.

 

[mikidymac]

Just keep running it , I am sure it will get better.

That was a joke, you need to find the issue because when you keep running it lean on top end you will do more damage every time.

 

[jemery.wa]

So where should I be looking for a Lean problem? I am going to go back into the fuel pump and replace the diaphragms, they looked good when I went through the carbs so I didn't replace them.

 

[jemery.wa]

I had the fuel pump out and did see that one of the diaphragms has a small crease one side, the plug ripped when taking it out. Do you think this could be causing a lean condition?

 

[mikidymac]

Yes, it is possible.

 

[jemery.wa]

I did take it back out and rode it, I couldn't quite tell if it was hitting a rev limiter at 6.5k or just a cut out, it died then did the typical slow start. I went back and adjusted the high end adjustments about 1/4 turn and took it back out. rode quite a ways at between 5.5-6k but would still die out when you push it to 6.5k for over 30 sec. I took it to the trailer and while in the water revved it up for awhile. It doesn't die out and it smells somewhat rich. Are you convinced that it is leaning out? Could it be something electrical/electronic?

 

[mikidymac]

Electrical is always a possibility.

 

[jemery.wa]

I replaced the fuel selector and also the solenoid and positive battery lead. Starts much better but still will die after full throttle for awhile, does last longer but still dies and does crank better but still slow when it dies. It sounds like it is hitting the rev limiter when it isn't even full throttle, I think I might have to do a block check to see if it is sealed, I can't think of why else it would be leaning out if that is what it is doing.

 

[artr]

I've read a lot about non OEM MPEMs causing problems or not working properly. I would try a simple test of disconnecting the battery for a minute after it dies from running at 6K rpms. Maybe completely resetting the MPEM will solve some of the restarting and rev limiting problems you have after it first dies out.

 

[jemery.wa]

I have the engine on the bench now, I have pretty much figured that the engine is leaning out on the PTO side and that is what is probably causing my problem. I have removed the PTO to replace the seal, not sure if that is a problem but might as well sine I am going to replace the output anyways. My rotary valve cover seems to have some scoring but I am not sure what the tolerance for that type of thing is, the block side look good. one interesting thing is that I did notice what looks like a score mark that seems to line up with TDC but the rotary valve doesn't quite line up with it as it was installed when I took it apart. I have a angle tool on the way so I can make sure it is installed correctly but my question is, if this was off could it cause the lean condition that is causing my problem?

 

[jemery.wa]

Did a squish test before I stripped the heads and cylinders off and both where close to 2mm, I know that is to much so I will have to address that when I put back together, not sure how that affects the performance. here are pics of the pistons for interpretation.

 

[mikidymac]

Those pistons are done and look to be running lean. I would look at carbs/fuel system as the cause.