Mystery, 2001 Seadoo gts acceleration issue

[TazMojo]

Anybody know what the acceleration issue might be? When the out of the water acceleration is great. When in the water, I try to accelerate it dies. It all started with a little hesitation to full acceleration. Now won't accelerate at all.

 

[kenfyoozed]

This is due to the back pressure that is applied to the engine while in the water through the pump. Same reason that the trailer idle stepped is twice that of in the water idle speed. What is the condition of the carbs and fuel delivery system? When was the last time they were cleaned?

 

[mikidymac]

Not really sure what your asking actually?

Running on the trailer will tell you absolutely nothing other than it runs. If it’s having issues in the water it could be fuel, spark or compression.

 

[TazMojo]

This is due to the back pressure that is applied to the engine while in the water through the pump. Same reason that the trailer idle stepped is twice that of in the water idle speed. What is the condition of the carbs and fuel delivery system? When was the last time they were cleaned?

The carb was rebuilt . Clean as a whistle. The issue started before the carb was rebuilt. For a 2001 model, it probably only has 12 hours of use sense new. Sat in storage most of its life. I drained the fuel & flogged the cylinders before storing the ski. Ski has fresh fuel. I bought a new fuel filter for it. I don't believe thats the problem sense the ski runs perfect out of the water.

 

[kenfyoozed]

If it has sat for that long there may be other parts that have partially seized.... like a bearing going bad and while out of the water it has the power to over come but with the added pressure of the water it can't overcome them both. I would start with checking compression. If that checks out I would isolate the pump from the engine and test both. It it runs great out of the water I would tend to think there is a pump issue. Wear ring still good?

 

[mikidymac]

I would check the fuel selector and strainer for air leaks. Was the carb rebuilt using new Genuine Mikuni Parts.
From what you are describing you are experiencing a fuel starvation issue.

 

[benjilafouine]

Try pulling the choke when it dies. If it picks up there is something wrong with the fuel/air mix.

 

[TazMojo]

Try pulling the choke when it dies. If it picks up there is something wrong with the fuel/air mix.

Try pulling the choke when it dies. If it picks up there is something wrong with the fuel/air mix.

Yeap, If I pull the choke the engines starts to accelerate. Then dies. My guess is that it maybe a fuel pump issue

 

[mikidymac]

You are running lean.
1. Fuel strainer is sucking air.
2. Fuel selector is sucking air.
3. Carbs aren't rebuilt correctly or aftermarket kits were used.

 

[TazMojo]

Found someone with the same described issue on youtube. It was a weak fuel pump. Mine is 18 years old. Replacement cost $189.00. Will install, and post the results.

 

[mikidymac]

A 2001 GTS doesn't have a replacement fuel pump. The fuel pump is part of the carburetor so I am nit sure what you found for $189?

 

[TazMojo]

Fuel pump carburetor.Mikuni Super BN Series 40mm I-Series Carburetor with Accelerator Pump | eBay

 

[JeremyD615]

Fuel pump carburetor.Mikuni Super BN Series 40mm I-Series Carburetor with Accelerator Pump | eBay

That’s not a fuel pump. That’s a complete carburetor, and I can’t tell from that listing whether it’s correct for your ski or not... it looks to be the correct body, but I have no idea how that carb comes jetted...