02 GTI LE Acceleration Problem

[USC Justice]

I have an acceleration issue with a project ski that I have been working on. It is an 02 GTI LE. I bought it with a blown motor. Hull was in beautiful shape.

The problem is this. In the morning (or whenever), I first jump on the ski, everything is fine. Fires up on the first push of the button and will get up and go and plane out and get up to speed. It is from the start just slightly slow on the pop up out of the water. The problem is that as the day goes on, the amount of lag between grabbing a handful of throttle and the actual acceleration lengthens. After running the ski for say an hour or so at ½ to full throttle and then you slow down for a no wake zone and then accelerate again, it may take as much as 30 seconds from the time that you go to full throttle until the ski actually responds and comes up and out of the water.

I know that an aftermarket impeller (like a skattrak swirl) will improve pop up and so on out of the water some. I think this is something else.

Here is what I have done in the process of working on the ski…

SBT Motor
New Wear Ring
New Pump Oil and O-Ring
New Fuel Lines (just to be on the safe side)
New Oil pump assembly
New Mikuni Carb (was told the old one was beyond saving)
New Starter Solenoid

Any thoughts as to what might create such a condition? I idly wondered if it might have been the MPEM for some strange reason, so I have swapped the MPEM from my 99 GTI into it (Hey, same motor, so may as well). This resulted in no change whatsoever.

 

[LouDoo]

Sounds like cavitation, since you have replaced the wear ring it's probably the carbon seal. For testing put a couple of cable ties around the carbon seal bellows, see if that helps. If it does replace the carbon seal.

Lou

 

[El Toro 33809]

Is the motor reving out, but the ski isn't picking up the speed as it should? Or is it that the engine RPM's aren't picking up?

 

[USC Justice]

The motor is not picking up revs. Almost like there is a delay before the craft accepts the command of more throttle.

Carbon Seal? Forgive me, not entirely sure on this, can you elaborate?

 

[USC Justice]

doesn't feel like any type of cavitation that I have felt before from things like bad wear rings.

 

[El Toro 33809]

If it isn't reving out, it's not a cavitation issue. The carbon seal is what seals the driveshaft where is passes through the hull. A worn carbon seal can allow the jet pump to suck air and cavitate.

You indicate that the carb was replaced. I am leaning towards that being the culprit, although I'm stumped as to why it would run okay for the first 30 minutes, then lose performance. Something else needs to be addressed before switching out the impeller.

 

[LouDoo]

Try leaning out the carb. just slightly, turn the LS screw in maybe 1/8 to 1/4 turn. Also your carb. has an accelerator pump, you might see if the check valve is working, also if you haven't done so change out the grey lines on the accelerator pump circuit to 1/8" tygon.

Lou

 

[USC Justice]

OK. Tried adjusting the low speed screw 1/4 of a turn and there was no noticeable effect.

Is the check valve that you are referring to the check valve on the fuel line coming off the fuel tank? If so, I actually tried removing it entirely and this also had no effect. if the valve is correct as it was plugged into the side of the ski, then it should allow air to flow into the tube and down into the tank, but not in the other direction correct?

This is the same behavior as before buying the new carb, but not nearly pronounced as it was previously. Just wondering what else I might be missing.

Thanks

 

[LouDoo]

Are you adjusting the carb. on the trailer or in the water? It's nearly impossible to adjust it on the trailer. I just looked at the parts diagram there doesn't appear to be a check valve on the parts diagram.

http://fiche.seadoowarehouse.com/se...19&modelid=2002 Sea Doo PWC GTI LE CARBURETOR

Lou

 

[USC Justice]

I was adjusting the carb in the water. I wouldn't even try out on the trailer. The lower screw on the carb right hand side (towards front of ski) is the low speed screw correct?

 

[LouDoo]

It's part no. 33, the screw with the "T" handle on it.

http://fiche.seadoowarehouse.com/se...19&modelid=2002 Sea Doo PWC GTI LE CARBURETOR

I just re-read the thread, now I'm thinking it might be the rectifier, try this. Disconnect the red wire on the rectifier, the rectifier is located in the front E-box, be sure the battery is charged because the battery will not charge with the red wire disconnected. If this fixes the problem, replace the rectifier.

Lou

 

[USC Justice]

OK. Could I swap one from my project ski (98 GTI) into this one? What makes you think this might be the culprit? That the part is overheating and thus creating the lag? I am trying to understand it in addition to fixing it.

 

[LouDoo]

The reason I'm thinking it's the rectifier because I had a very similar problem with one of my ski's back in early spring, after rebuilding the carbs. and a bunch of other things, Chester suggested that is was the rectifier. Chester is like the SeaDoo God.

I'm not sure why the rectifier breaks down other than it's an electrical part and the ski was 15+ years old, but like your ski it wouldn't do it all the time.

Unlike the professionals on this forum the advice that I give is from personal experience, if I see a question that I don't think a can give a reasonable answer I just won't answer the question, or refer to a professional like Dr Honda.

Lou

 

[USC Justice]

I appreciate the help, and did not want to sound disrespectful. I'm learning as much as I can as I go along.

I will give that a shot and report back.

 

[USC Justice]

OK. Been riding today with the rectifier from my 98 GTI swapped onto the 02 GTI LE. No difference in the acceleration lag. What else might I not be thinking about? Really puzzled by this one. Still possibly a Carb setting even though it is brand new? Any thoughts or help would be appreciated.

 

[USC Justice]

OK, another update.

In thinking perhaps the jets and pop off was wrong on the brand new carb, I pulled that one off and swapped on the carb from my 99 GS which was running perfectly. The same problem of acceleration delay exists with the other carb on it. After putting it back on the trailer and packing up for the evening I'm left wondering. It has a new oil pump on the ski (done at the same time as putting in the SBT motor).

Would the adjustment being wrong on the oil pump arm (that attaches to the cable going to the carb) cause the ski to bog like this? For example adjusted too rich so that at idle it is mixing too much oil, not burning off as easily and thus causing it to delay? That would also make sense to me as it is not as pronounced when first starting up.

Open to any other suggestion as well. Willing to pretty much try anything.

Thanks in advance.

 

[Dr Honda]

With what you are describing... it sounds like it's over-heating. Does your buzzer work? You may want to check your sender on top of the head. It should be "open" normally... and close around 195 to 205 Deg F.


If the oil pump was out enough to cause issues... then you would have a ton of smoke.


Now... are you saying that the known good carb has the same issue?

 

[USC Justice]

Tony,

Thanks for your response. I would assume that the buzzer works as it beeps every time I put the key on the ski. I don't have an abnormal amount of smoke coming from the back of the ski. The ski has never felt abnormally hot to the touch after riding. about the same as the 99 skis, maybe a touch warmer but not much.

I am saying that the good carb from my 99 GS shows no difference at all on the 02 GTI LE when installed.

 

[KCB 850]

After running the ski for say an hour or so at ½ to full throttle and then you slow down for a no wake zone and then accelerate again, it may take as much as 30 seconds from the time that you go to full throttle until the ski actually responds and comes up and out of the water.

During this time interval what is the engine doing? I suspect it is sputtering and misfiring. If so it sounds like you may have a coil that needs replacing. The reason being is the wiring is "breaking down" internally as a result of the increase in heat.

Coils do breakdown on occasion and given all you have already tried it seems to be plausible. You can test the coil with a quality multi meter. The instructions are in the service manual.

Also don't get frustrated you will get it running.:thumbsup:

Good luck,

Robert

 

[USC Justice]

During the time when at speed, there is no sputtering, misfires, or other madness. The ski runs quick and smooth once up and moving.

Could a bad temp sensor on the top of the motor cause the ski to think it is overheating when it isn't and thus cause the acceleration issue? I'm not going to get to the lake this weekend, but I can try swapping the sensor over from a good ski to test that too.

Thanks.

 

[KCB 850]

During the time when at speed, there is no sputtering, misfires, or other madness. The ski runs quick and smooth once up and moving.

Could a bad temp sensor on the top of the motor cause the ski to think it is overheating when it isn't and thus cause the acceleration issue? I'm not going to get to the lake this weekend, but I can try swapping the sensor over from a good ski to test that too.
Thanks.

No, I was inquiring about the estimated "30 secs from the time that you go to full throttle until the ski actually responds and comes up and out of the water." Does it sputter and miss or just it just go flat then pickup some revs?

Robert

 

[USC Justice]

Ah, I understand. No, it doesn't miss or stutter when you first grab the throttle. It does nothing like you are still idling, and then it starts to build revs.

 

[KCB 850]

Ok that's certainly different. Time to think about that for awhile and read up on the 02 GTI (not really familiar with it ya know).

Robert

 

[USC Justice]

Thanks. Any help would be appreciated. It is the 717, and the MPEM interchanges with my 99 GTI. At least from everything I can tell it is the exact same as the 99 and just the hull is different on the 02. All the internals look and act the same.

 

[KCB 850]

Ok,

I have thought about it and I keep coming back to the accel pump being the most likely cause based on your symptoms. Having said that I do not have any idea why it does it only when it does. So get out the manual and double check all the connections including your hoses and cables. Then this web site is chock full of posts, do a search and spend some time reading them. Eventually you will hit on something.

Unless as Lou said earlier, someone comes along who had the same experience. This is going to be tough to diagnose w/o putting hands and eyes on the project.


Robert