1994 GTS Detailed troubleshooting after dying but still not working

[PorkChopsM]

Hey everyone, new Seadoo owner but not new to carb repair and troubleshooting or riding these in my youth. I purchased what looked like a well cared for 1994 GTS a few weeks ago and was able to run it strong for two days before encountering trouble. When using it on a third day I was idling and waiting to pull a wakeboarder and the ski cut out. I was able to restart it to a very rough idle with no power and since then I have not been able to get it to run normally.

Things I did wrong that may have contributed:
- Used gas with ethanol but did use octane booster (I know... I know...)
- Topped off oil with Yamaha W2

Symptoms:
- YouTube of it running located here:

- Very rough idle when I get it to start (requires multiple starting attempts and it will usually idle for 10 to 15 seconds before dying)
- No change in or out of the water
- Giving it throttle has zero to extremely little change
- Choking the engine instantly kills it
- Very dark oil residue coming out of the back/bottom when testing dry
- Fuel before and after fuel line replacement appeared to be flowing fine
- I took out a spark plug and the pressure seemed strong -- I don't have a compression tester but could rent one if needed.

I have searched these forums a lot prior to posting and tried to research what I could. Here are the troubleshooting steps I took:
- Grey fuel lines replaced with clear marine tubing -- replaced each line at a time validating the lines are routed properly and can see gas moving when idling. Grey fuel lines did have some green residue inside but didn't appear horrible.
- Fuel selector replaced with one from ODS
- Replaced the spark plugs with the right NGK ones and gapped at .20 and validated it's getting spark
- Used the ODS carb kit to replace the carb filter (filthy), pump gasket, and diaphragm gasket. There was quite a bit of sand in the carb. Completely cleaned and scrubbed it down. I did not replace the other carb components because they seemed to be functioning.
- Emptied the gas tank and cleaned it out completely -- didn't have much inside except some sand and other minor debris
- The fuel baffle is clean and there was no filter/baffle at the end (I don't think the GTS's came with anything?)
- Validated fuel filter is clear and it appears the o-ring is seating properly
- Partially filled gas tank with rec no ethanol gas
- Fully charged the battery

Again, after all of the troubleshooting it ran exactly the same as before I started and still rough idled identically. Did I make a mistake to not break the carb down completely per this write up? It just didn't seem to be in nearly as rough shape as the one in the tutorial. This forum has great resources and has helped me get this far. Any ideas on other things I can try? I really thought after all I read this would take care of the problems along with the new fuel. Thanks!

 

[POPPS]

Since the one microfilter is plugged,,,and you have "rich exhaust,",,do a compression test, that carb may have been fuel deprived and you have a scored piston.

 

[CTM03]

You need compression tester for sure.

 

[PorkChopsM]

Thanks for the direction. I picked one up this AM and just gave it a test. Looks to be 130 for the front cylinder, it held at 130, and I tested it multiple times. Back cylinder is 140. I did some researching — is 130 in the range of acceptable? Looks like I am back to taking the carb off again and going through everything and replacing all of the parts. My new plugs look like they have an oil gas mix on them from my testing yesterday

 

[CTM03]

I've read in multiple places that having that big of a spread between cylinders isnt acceptable. They should be as close to matching as possible. 130 is getting low as well, I believe.

 

[CTM03]

I've read in multiple places that having that big of a spread between cylinders isnt acceptable. They should be as close to matching as possible. 130 is getting low as well, I believe.

I've got both cylinders running at 150 in my 94 Seadoo GTX.

 

[PorkChopsM]

Would it be enough to cause these problems or just be non-ideal? I’ve got the carb apart but am working on the plate screws that lead to the jets. Need to use some heat.

 

[mikidymac]

Compression isn’t ideal but your issue really sounds carb related.

Follow the carb rebuild thread sticky exactly.

Replace all the parts in the kits and the needles and seats.

 

[PorkChopsM]

Thanks for all of the help. The carb how to is a life saver. I cleaned, replaced, and checked every part. Unfortunately, while the ski started up immediately in the first push of the starter it is still running almost exactly the same as it did before… it just seems easier to start. Below are videos of it running. What perplexes me is I can use the throttle (and I can see it opening and the oil injection lever pulling too) and even spray in small amounts of lubricated carb cleaner and there is no change it how it is running. I don’t know how that is possible. I also checked the voltage. Roughly 12.5 prior to starting and about the same when running. Maybe very slowly increasing… but at least isn’t widely changing.

Any other thoughts?

Video links:

 

[CTM03]

I mean I don't want to say it but to me this sounds like I scored cylinder. Somebody more experienced jump in here though, I'm new here.

 

[PorkChopsM]

Well, interesting news while I was returning the compression tester. I explained to the employee and what I was doing at a high level and then he let me know that he had been a Seadoo mechanic for 5 years! Small world. So good news, he suggested I rent a borescope, which I did, with pics below. Bad news, when I showed him the video of the engine running he just said “oh that’s really bad.” He and I discussed all of the troubleshooting and so that makes me think he is in the same page as you all and that something in the engine is amiss. I also included some pictures of the spark plugs. The one from the cylinder with less pressure is clear and with a distinct black ring at the end. Not sure if that indicates anything. He borescope has a long camera that doesn’t articulate well. I really couldn’t get clear pictures of the cylinder walls.

 

[POPPS]

You don't need to borrow a boroscope,,,just remove the cylinder head,,,that model has reuseable "O" rings,,,torque to 15 ft pounds I believe.

 

[PorkChopsM]

Thank you, that's my next step. Top end rebuild kits look like they are ~$220 and some YouTube how to's look pretty straight forward. I guess cracking it open is the only way to know what the damage is and if a top end kit will fix it. More to come!

YouTube link for top end rebuild

 

[PorkChopsM]

Ok so now I am really confused. Took off the top end and under the cover was water and some sand! This has only been used on freshwater. And then I took off the head cover… and there is what looks like water near the cylinders, not in the cylinders. When the ski shut off I had been idling, going into reverse, and then neutral. Is there any chance water could have backed up into the engine? This was not done aggressively and on a very calm lake. Could it be water locked? I previously placed paper towels over the spark plug holes and ran the starter for a few seconds and no water came out — just some minimal two stroke oil. Looking at the pistons they both looked fine without putting or damage and the rings looked good. The pistons both moved freely with light pressure and both returned to the same position at the top, so I don’t think the rods are bent.

Any thoughts now? If I was using the neutral and reverse lever is there anything that could inhibit it from starting? I don’t see anything electrical that would retard the starting. Also, when testing at the lake I moved the lever back and forth while it was running poorly and I could see the direction of the jet changing. Thanks!

 

[mikidymac]

Perfectly normal. A little water will stay in the head and leak out when taking it apart.

 

[PorkChopsM]

Thanks #mikidymac. Any thoughts on where to come from here? I expected to see piston damage and now that I do not I'm not sure what a next step is. Spark and fuel are good and compression is decent (140/130).

 

[mikidymac]

The very black piston tops and cylinder hear point to it being lean.

 

[PorkChopsM]

Thanks again for the reply and after researching more I see what you mean about the lean condition. Is the way to fix that replacing the pistons and rings with one of the kits? Or can it be more than that? Hoping to get the ski on the water in two weeks or less -- will buy the kit today if we think it can make a difference.

 

[mikidymac]

I would still do the carbs correctly first before a top end.

 

[PorkChopsM]

I think I got the carbs working well now. It instantly started up but still runs very poorly -- exhibiting the same bad idle and lack of throttle response from before. If it runs lean can it just kill the rings and pistons or will it always score the cylinders? I looked at pictures online and don't see the cylinder wall scoring I would expect.

 

[mikidymac]

Running lean will eventually score the pistons and cylinder walls, just depends how long it is running lean and where in the powerband it is lean.

 

[PorkChopsM]

Ok, I buttoned the engine back up after noticing *no* scoring of the cylinder walls or damage to the pistons. Tops were definitely black indicating lean — I cleaned them up a bit. Disappointingly I cleaned up the engine and put it back together, tightened everything up to spec, and started it again. Exact same behavior as before. I turned out the low speed screw a 1/4 of a turn and it idled a tiny bit faster but still had major stumbling. I think the carb is working fine because it instantly starts, which you will see in the video here.

Is there any way for timing to get thrown off on these things? From all of the how to’s I’ve read and troubleshooting I have done this doesn’t seem to be adding up.

 

[POPPS]

A stripped rotary valve brass gear on the crank will throw off the timing,

 

[PorkChopsM]

So last post of the night -- I am wondering if I have a bad coil. I tested each spark plug and I can see that they are sparking. When it is running (like in the videos above, idling very poorly) I can take off the rear spark plug and there is no change. It appears that cylinder is not firing. If I remove the front spark plug the engine instantly dies. I cracked open the sealed electrical box and everything looks very clean. All fuses in good shape. I couldn't figure out how to get the spark plug wires out for testing Ohm resistance and so I left those alone. I poured some 50:1 gas in the top of the cylinders and put the spark plugs in to see if that would change firing or anything -- still did not affect it and it ran poorly. Since the lanyard switch, stop switch, etc. still work I don't think it is the MPEM. Any favor me ordering a replacement coil?

Link to eBay new one that looks like it will work:
SeaDoo Ignition Coil SP 1992, 1993, 1994, 1995, 1996, 1997 OEM# 278000202 | eBay

 

[1of500]

Try triming the ends of the plug wires and reinstall the plug boots