1998 Sea Doo GSX Limited - 12V Low

[MSUchurldr]

Well my recommendation would be to try to diagnose the problem before taking it in, as most issues with these skis can be dealt with inexpensively at home and then if you have to take it in, you know exactly what work they need to do...

The carbs being rebuilt by the previous owner wouldn’t change anything for me. The internal passages on these carbs are really small and easy to clog up, and the ethanol gasoline that we have these days does not help. For the $100 or so that it costs for all of the correct rebuild parts, I would never replace a motor without going through the fuel system at the same time...

If i have the right tool I’m going to check the compression before i take it to the mechanics tonight...and speaking of that what do i do with the spark plugs when checking the compression to make sure the ignition doesn’t fire. I don’t think my model has a spot to ground the spark caps

 

[JeremyD615]

Most auto parts stores have free rental for compression gauges... Your ski should have spots to ground the cables. I’ve never been under the seat of that model ski, but they should be close to the cables. Trace the spark plug wires back from the plug to the coil, and there should’ve a set of posts somewhere close by. They may be next to the rear electrical box... If you can’t find them, I’m sure one of the guys with more experience in that hull will pop in shortly and point you in the right direction.

 

[mikidymac]

Also most people buy the junk aftermarket carb kits to do the rebuilds then get frustrated when it doesn't run.

 

[Sportster-2001-951C-Stock]

Work on it yourself now, use your money for a compression gauge instead of a service shop and get to it, you can do this and should.

Record your at-rest overnight battery voltage, which should be slightly more than 12.5V. Then fire it up in water and measure again at 4,000 RPM for a few minutes, it should be near 13.8V or close to it under these conditions if the battery is good and charging system is working.

Don't charge the battery while both terminals are connected to the system, disconnect one of the terminals 1st, I usually disconnect the "-" terminal.

 

[Sportster-2001-951C-Stock]

Most auto parts stores have free rental for compression gauges... Your ski should have spots to ground the cables. I’ve never been under the seat of that model ski, but they should be close to the cables. Trace the spark plug wires back from the plug to the coil, and there should’ve a set of posts somewhere close by. They may be next to the rear electrical box... If you can’t find them, I’m sure one of the guys with more experience in that hull will pop in shortly and point you in the right direction.

Good point, need to ground the plug wires while compression testing.

FWIW, All the rotary valve engines I've seen have the plug wire grounding posts on the motor not far from the plugs.

 

[Sportster-2001-951C-Stock]

Also the carb was rebuilt by the previous owner, so that won’t be needing any work

It all depends on the quality of work he did though, it's possible he used inferior parts or was inexperienced, maybe he knew what he was doing, hard to say.

But if it runs correctly in the water including easy warm restarts (a benchmark test) that's the acid test.

 

[MSUchurldr]

Also most people buy the junk aftermarket carb kits to do the rebuilds then get frustrated when it doesn't run.

the guy i bought it from said he spent $800 on the replacement carb parts...

 

[mikidymac]

Even if you bough 2 brand new carbs they wouldn't be $800 so I don't think he was telling the truth. I always assume any new to me ski needs new carb kits and don't take anyone's word for it. Every single one has needed the carbs done BTW.

 

[Sportster-2001-951C-Stock]

Also most people buy the junk aftermarket carb kits to do the rebuilds then get frustrated when it doesn't run.

Yep, or worse, install the junk kit and fail to clean the tiny passages, which can present a challenge and is typically the root problem in the 1st place (invisible trash and corrosion lodged tightly in tiny passages).

 

[MSUchurldr]

Even if you bough 2 brand new carbs they wouldn't be $800 so I don't think he was telling the truth. I always assume any new to me ski needs new carb kits and don't take anyone's word for it. Every single one has needed the carbs done BTW.

i thought that sounded insanely high, i plan to rebuild it myself again in the near future anyways

 

[Sportster-2001-951C-Stock]

the guy i bought it from said he spent $800 on the replacement carb parts...

Maybe he paid a shop to do the work, it adds up quickly. If you suspect an issue, before tearing then down at least check the mixture screw settings. This will give you some idea b/c if these are incorrect the work is questionable. Make sure you know how to accomplish this, you have to count the clockwise turns of the mixture adjust screw to the fully seated position (don't crank tightly on them, overtightening damages the soft metal seat).

 

[MSUchurldr]

Maybe he paid a shop to do the work, it adds up quickly. If you suspect an issue, before tearing then down at least check the mixture screw settings. This will give you some idea b/c if these are incorrect the work is questionable. Make sure you know how to accomplish this, you have to count the clockwise turns of the mixture adjust screw to the fully seated position (don't crank tightly on them, overtightening damages the soft metal seat).

said the gas lines and “other little things” were included in that $800. who knows, my problem now lol

 

[JeremyD615]

Good point, need to ground the plug wires while compression testing.

FWIW, All the rotary valve engines I've seen have the plug wire grounding posts on the motor not far from the plugs.

Are the posts bolted to the motor on the 951’s? I know they are on the 580, 657, and 720 skis, but at least on the 787 XP’s, they are molded into the rear Ebox housing. I wasn’t sure if they stayed that way for the later skis or went back to the original style...

OP, if the previous owner says he spent $800 on having the carbs redone, I wouldn’t trust that any of the work was actually done. It’s possible that he got ripped off by a mechanic, but it’s even more likely that he was making some things up, as private sellers tend to do sometimes... When I bought my 96XP, I was even told it had a “hot cam” in it, which was interesting since rotary valve motors don’t have camshafts...

The carbs on these machines are really simple devices, and with a couple of hours and a little patience, anyone can rebuild one on their workbench at home. Don’t let the work intimidate you. Just go through the diagnostic process and find the root cause of your issues before you start throwing too many parts at it, but be aware the carbs are suspect and really should be done if you want the ski to be and stay reliable...