94' GTX cutting out. Anybody wanna give it a crack?

[Sandman251]

I have a 94' GTX 650. Compression is 150/144. Was oil hydrolocked after sitting for a few years, but fired right up after a few "plugs-out" cycles. New coil, carbs rebuilt and new battery. Starts and runs great. Got it to the lake and it ran 40mph then it quit in a turn. Started right back up and ran great.... then just cut completely out again. I don't mean down to idle or sputtering till it quit. I mean like somebody pulled the plug on it. This happened a couple more times and we brought it back in. We guessed electrical. Ended up finding frayed wires at the stator housing. Repaired and tried again. Same result. This time it wouldn't fire right back up on the lake but did start back up at home. Best guess anyone?

 

[etemplet]

Did you do resistance testing on the stator ? What about the safety switch? When the ski won't start are you getting "no fire?"

 

[Sandman251]

The direct answer to that question is no, we have not performed those tests. The problem is when we get the ski home it always starts and runs fine. What kind of testing to the kill switch/stator would be revealing while the ski is running fine?

 

[etemplet]

Nothing I can think of. LOL I had an issue with my 1996 SPI. Every now and again it wouldn't start. I checked fire and it wasn't getting any. I removed and replaced the safety cap/lanyard and the ski fired right up. Purchase a spark testor from the auto parts store for about 7 bucks. When the ski kills or won't start put it on there and check the spark. I don't think it is your stator. Good Luck !

 

[GGuillot]

I have a 94' GTX 650. Compression is 150/144. Was oil hydrolocked after sitting for a few years, but fired right up after a few "plugs-out" cycles. New coil, carbs rebuilt and new battery. Starts and runs great. Got it to the lake and it ran 40mph then it quit in a turn. Started right back up and ran great.... then just cut completely out again. I don't mean down to idle or sputtering till it quit. I mean like somebody pulled the plug on it. This happened a couple more times and we brought it back in. We guessed electrical. Ended up finding frayed wires at the stator housing. Repaired and tried again. Same result. This time it wouldn't fire right back up on the lake but did start back up at home. Best guess anyone?

Assumptions, you rebuilt the carbs with OEM, tested pop off, pressure test, etc. I'd rule out fuel delivery problems, bypass the fuel selector see if that changes anything.

 

[mikidymac]

As said above you need to determine if it is fuel or spark.

If it was me I would take a new spark plug with me. As soon as it dies but won’t start pull the seat, install the new plug in the wire boot and see if you have a good strong spark. You can do this almost immediately after it dies and go from there.

 

[Sandman251]

Assumptions, you rebuilt the carbs with OEM, tested pop off, pressure test, etc. I'd rule out fuel delivery problems, bypass the fuel selector see if that changes anything.

Wouldn't a faulty or clogged fuel selector be a chronic problem and not intermittent?

 

[Sandman251]

As said above you need to determine if it is fuel or spark.

If it was me I would take a new spark plug with me. As soon as it dies but won’t start pull the seat, install the new plug in the wire boot and see if you have a good strong spark. You can do this almost immediately after it dies and go from there.

Thanks, I will definitely do that. The problem is, four of the five times the ski died it started immediately. I would hate to see Spark, then Chase my tail for a month tracking down a phantom fuel/ air problem.

 

[etemplet]

When it cuts out, is it like turning the switch off or does is sputter and won't take fuel? A fuel issue generally doesn't fire right back up and run great. My favorite $5.00 tool. Easy see if you are getting fire and the ski will start. I wouldn't leave it in place though. LOL Great tool !!

 

[kmarts]

Wouldn't a faulty or clogged fuel selector be a chronic problem and not intermittent?

If its sucking air it might not show at lower rpm... but I also don't think it would fire right back up if you were running the carbs dry.

 

[Sandman251]

When it cuts out, is it like turning the switch off or does is sputter and won't take fuel? A fuel issue generally doesn't fire right back up and run great. My favorite $5.00 tool. Easy see if you are getting fire and the ski will start. I wouldn't leave it in place though. LOL Great tool !!

As I mentioned above, when it cuts out, it is like flipping a switch. It will fire right back up... run up to 40 mph and the switch flips again. So like I said, I can never test the ski when it is in a fault condition.
I did have a fairly smart 2-stroke guy tell me it was a loose/shorting wire somewhere. His theory was that the forward motion and bumping aggravates the wire into a fault condition. Slowing to a stop settles the wire back into position. It's a theory that makes sense, I suppose. Where should I begin? Grounds? How many ground wires are there If anybody knows?

 

[etemplet]

Download the repair manual and spend some time with the wiring diagram. Check which ones are responsible for the spark circuit. You may have a problem in a connector or a broken wire that is failing. It could also be your Electronic Control Module. I"d check the safety switch first. Be patient and methodical. Good Luck.

 

[Chester]

In my experience, a bad MPEM is the cause of this. It's definitely not a fuel problem.

Chester

 

[Sandman251]

In my experience, a bad MPEM is the cause of this. It's definitely not a fuel problem.

Chester

Thanks for the response, Chester. Can you take a minute and tell me a little about your personal experience? How did you diagnose a bad MPEM?

 

[Chester]

First, make sure all the wire connectors and grounds are tight. Test the resistance of the ignition coil with an ohm meter from one plug wire to the other. I had a customers 96 GTX that was doing the same thing, it turned out to be the MPEM. Make sure you check all the simple things first.

Chester

 

[seadoo@19072]

I have a 94' GTX 650. Compression is 150/144. Was oil hydrolocked after sitting for a few years, but fired right up after a few "plugs-out" cycles. New coil, carbs rebuilt and new battery. Starts and runs great. Got it to the lake and it ran 40mph then it quit in a turn. Started right back up and ran great.... then just cut completely out again. I don't mean down to idle or sputtering till it quit. I mean like somebody pulled the plug on it. This happened a couple more times and we brought it back in. We guessed electrical. Ended up finding frayed wires at the stator housing. Repaired and tried again. Same result. This time it wouldn't fire right back up on the lake but did start back up at home. Best guess anyone?

 

[seadoo@19072]

I have a '94 GTX. Exactly the same thing happened to me. Check your wear ring, propeller or the pump. If it is showing any damage, it will not pump enough water into the block to cool the cylinders and pistons. The heat will cause the cylinders and pistons to over heat and seize. When they seize, it shuts the engine down like you you pulled the kill switch. In a couple seconds, the cylinders and pistons cool down enough to start. At idle and slow throttle there will be enough water pumped into the engine block and it will run OK until you try more throttle.