1998 GTX LIMITED ran for 20-30min then died from 4000 rpm…. It restarted… then repeated died about 2 min later.

[EdwinBland]

I have a 1998 GTX LIMITED recently acquired.

It had a recent top end rebuild… with 125/115 pressures…. Not ideal… but I have a 99 with 110/110 pressures that runs like a champ.

Carburetor was recently cleaned… replaced all fuel lines…

It ran on the hose for 20 min yesterday to warm up and adjust carburetor.

I took to the lake on a warm day… today…
A clean start… idled ok on trailer about 10 min… then idled around another 5-10 min… then started longer runs up to 30 mph for about 10 min… then up to 40 mph… revving up to 5000RPM. The engine then acted like it wasn’t getting fuel or spark… dropping down to 1500 RPM and then dying… I was able to restart… and headed back to dock… it ran OK on way back albeit at lower throttle… so I headed back out… it did it again… and finally stopped starting…
Got to try out my shiny new paddle today…

It has a full gas tank.

I did notice on the carburetor lines that one of them often has bubbles in it or no gas… on my 99 GTXL’s these always have gas in them..

Thoughts?

Suspect fuel system, faulty coil, other?
The spark plugs are pretty new.

Any suggestions are welcome!

 

[tobytd]

Rebuild the carburetor’s, you can’t just clean them and expect them to work correctly. Genuine Mikuni parts only. Follow mikidymacs sticky to the letter. Replace the fuel selector. Also new needles and seats

 

[EdwinBland]

Rebuild the carburetor’s, you can’t just clean them and expect them to work correctly. Genuine Mikuni parts only. Follow mikidymacs sticky to the letter. Replace the fuel selector. Also new needles and seats

Tx tobytd,
I had replaced the needles and seats with the cleaning. Tested pop offs… both were at 21… cleaned high and low jets.
I replaced the fuel lines and fuel selector last week… however, I only have a single fuel filter inline… my other skis have 2 filters.
I will confirm the fuel lines and selector are functional…
I’ll find out how to test the coil…and rule out spark issues…
Will plan to pull the carbs and rebuild.

 

[JC-SUPERJET]

What is the Compresion after the break-in ride? Is it still 125/115 psi?

 

[tobytd]

21 pop off seems low. Did you get the three transition holes clean?
All of that run time out of the water or on the hose better keep an eye on the carbon seal.

 

[EdwinBland]

21 pop off seems low. Did you get the three transition holes clean?
All of that run time out of the water or on the hose better keep an eye on the carbon seal.

Are you referring to the low and high jets? I’ll need to see which holes you are referring to.
Agreed. I filled part of the hull with water with the front of the ski on a stand … to provide some cooling… and leak check…
The service manual says 21 pop off is within spec for the 951 GTX, but in the high side.

 

[SIMPLEARKANSAN]

I would check compression. I was told the only new fuel selector valves were of low quality. I am going to pressure test my fuel selector before I order a lesser quality selector. I have the same ski that I did a top end on and am almost ready to start for the first time. I fully rebuilt my carbs with Back to OEM kit. Replaced fuel lines, the fuel filter O ring, the fuel filter, cut back the spark plug wires 1/4". Replaced all my oil lines and oil filter. I will follow your thread for trouble shooting purposes and provide input as I run mine for the first time.

 

[EdwinBland]

Tx JC-SUPETJET and SIMPLEARKANSAN!

Retested compression… ugh… 125/70…. The guy I bought this from had done the top end… I only have $500 into it with trailer…it’s recoverable…
Looks like I need to redo the top end…
Hadn’t planned for that…
Would you suspect a bad/poor break in initiation or the top end install? Would love to avoid this next time… I thought I was pretty careful about not pushing it …

Tx for the inputs! When I redo the top end I’ll retest all the fuel lines, selector and spark gen path…

 

[mikidymac]

When you did the top end, did you bore the cylinders oversized and use new pistons and rings fitted by the machine shop?

Your first clue off the bat was the 10 psi difference. Even brand new they should have been identical.

You should only have the stock inline water separator/filter on all your Seadoo skis. There should not be any additional inline fuel filters.

If you didn't follow the carb rebuild thread exactly with all new parts then do it over the correct way or not at all.

There is never a reason to run them for 20 minutes on the hose, only a minute or two at most. The only purpose for the hose is to flush the cooling system, period.
Just fire them to make sure they run them get them in the water.

 

[EdwinBland]

When you did the top end, did you bore the cylinders oversized and use new pistons and rings fitted by the machine shop?

Your first clue off the bat was the 10 psi difference. Even brand new they should have been identical.

You should only have the stock inline water separator/filter on all your Seadoo skis. There should not be any additional inline fuel filters.

If you didn't follow the carb rebuild thread exactly with all new parts then do it over the correct way or not at all.

There is never a reason to run them for 20 minutes on the hose, only a minute or two at most. The only purpose for the hose is to flush the cooling system, period.
Just fire them to make sure they run them get them in the water.

Tx mikidymac
I had theorized that if the carbon seal has water over it it’s like being in the lake… think that did motor damage? I monitored the engine temp…
There seems to be different opinions on the net… Is that what Seadoo recommends?

The previous owner did the top end rebuild.
He just made me aware of it.

Can you point me at the carb rebuild thread? Happy to follow it…

On the filter matter… are you suggesting a reduction of fuel flow from more than one filter?
That would make sense.

 

[EdwinBland]

@mikidymac
I found: The Seadoo Carb Rebuild Thread
On your profile.

Much appreciated!
I’ll follow it.

 

[JC-SUPERJET]

After you rebuild the Engine, do an Air Leakdown Test on the Bench to find any possible Air Leaks.

Make sure you inspect the Crankcase for any orifices/cracks/breaks or damaged hose fittings/connections.

 

[EdwinBland]

Tx JC-SUPERJET!

I’ll need to know what made this one fail… so the next one isn’t a repeat… will take some time…

 

[mikidymac]

Tx mikidymac
I had theorized that if the carbon seal has water over it it’s like being in the lake… think that did motor damage? I monitored the engine temp…
There seems to be different opinions on the net… Is that what Seadoo recommends?

The previous owner did the top end rebuild.
He just made me aware of it.

Can you point me at the carb rebuild thread? Happy to follow it…

On the filter matter… are you suggesting a reduction of fuel flow from more than one filter?
That would make sense.

Running on the hose will not cause engine damage but it won’t do any good either.

The jet pump and carbon seal need lake water to cool.

No load on the engine will do nothing to help break in the rings.

Internet opinion is crap, especially Facebook. Yes, you should never have 10 psi difference between cylinders period. Only exception is a Yamaha 760 that is staggered from the factory because they were destroying rear cylinders.

Never trust anything the previous owner does.

Yes, additional filters can and do restrict fuel flow causing a lean condition on an already lean engine.

 

[SIMPLEARKANSAN]

Check your fuel selector valve. Mine leaked really bad. Wouldn’t hold pressure at all. Mine also has a cylinder with low compression. I ordered a new fuel selector from OSDparts.com. Got all my exhaust connected so once I get the fuel selector I’ll be ready to start it.

 

[RXsquared]

How did new fuel selector work out? I get mine from OSD Thursday. Thanks

 

[SIMPLEARKANSAN]

I’m waiting on my “Back to OEM” carb kit to be here on Thurs. I did go through the fuel system I’m a 2000 GTX and have it running nicely. All I need on my 98 gtx is the carb kit and it will be ready to start. Hopefully sometime this weekend.

 

[RXsquared]

I’m waiting on my “Back to OEM” carb kit to be here on Thurs. I did go through the fuel system I’m a 2000 GTX and have it running nicely. All I need on my 98 gtx is the carb kit and it will be ready to start. Hopefully sometime this weekend.

I get my OEM carb kit from OSD on Thursday also. Sounds like we're both rebuilding carbs on Friday. LOL. 2000 RX, my kid's. I got Nick's SS screw set, also got stainless hex cap screws for valve bodies and bracket that holds carbs together. Good luck on rebuild

 

[EdwinBland]

Update on the 951 carb engine:
Pulled the engine this evening… pics attached.
Findings:
1) Carb base gasket with chunk missing … on the bad cylinder. Suspect air leaking caused lean condition as folks mentioned above.
2) cylinder wall damage
3) piston appears toast

I just got a bore guage… haven’t taken measurements yet…
Think it needs bored or might a hone smooth this out?

I’ll have the crank checked… vs…
Can a crank be checked at home?
I have a bore guage, micrometer and feeler guages…

TIA

 

[mikidymac]

Bores are toast due to the scoring and pitting, bore oversized and new pistons and rings.
#1 rule of thumb...a 951 with a used crank from a seizure and new top end is not long for this world

 

[EdwinBland]

Tx mikidymac! I’ll get them packaged up to send out.

 

[mikidymac]

Tx mikidymac! I’ll get them packaged up to send out.

Where are you sending them?

 

[EdwinBland]

Not sure yet. Considering SES vs a TBD local shop. I prefer a local shop… but I’m happy to have recommendations. The SES recommendations sound nice and they’ve been easy to talk with on the phone.

 

[mikidymac]

LOL, i would avoid SES and FullBore at all cost.
The truth about ses...
It isn't their work that is the issue it is that once they have your engine you might not see it again for a few seasons and huge lack of communication after they are late.
Just search this forum and there is story after story of unhappy customers.

I only use Group K for my machine work, 30 years worth.
Local if you can find 2-stroke experience, not the same as a car engine machine shop. Some just don't have the experience.

 

[EdwinBland]

Wow!… that was a lot to unpack…
Does group K also provide a top end kit and be sure the bore matches the pistons?… trying to avoid paying again and again for my ignorance…

I’m in DFW, Tx… any local recommendations?
It seems that none of the local Seadoo dealers will touch anything older than 10yrs.

I welcome recommendations for rebuilt cranks as well.