Still chasing high RPM cutting out

[Colseadoo1955]

I thought I had my 1997 Seadoo GSI performance problems resolved. I found my charging voltage was too high and replaced the regulator/rectifier which cured that. However, it still has issues with loosing power upon acceleration and it's a definite missing out and not a surge. The new analog tach needle goes erratic when it happens and intermittently pops down to zero RPM but it never dies and if I shut it off it starts right back up and idles smoothly. Fuel filter, plugs, and plug wires are new, compression is good, had MPEC tested as good. Help fellas.

 

[POPPS]

usually fuel delivery issues,,,fuel selector/hoses/ carbs,

 

[Colseadoo1955]

You're right. It only has a single carb on it. I had it running in the garage with a hose running and had my son working the throttle. At higher RPM when it started cutting out, I enrichened the fuel with propane and it straightened right out. Just rebuilt the carb. I'll blow out the hoses and selector. What would I look for if I have to pull that carb back off?

 

[Colseadoo1955]

Tomorrow, I'm going to run a line to an external fuel tank to see if that cures this. If it does I'll know the carb is OK and if not, I'll know the issue must be in that carb itself. I have already cleaned it and installed a new carb kit, so as I'm then at a loss I guess I'll have to replace the carb. Online, I see most of the new ones are the BN40i and according to the manual I have a BN38. Any advice on the difference and/or would I have any issues installing a BN40i. I have a 1997 GSI with a single carb 717 engine.

 

[mikidymac]

No, don’t blow out the selector. The go bad from the inside and have to be replaced. Lots of engines have been ruined from bad selectors.

Did you follow the carb rebuild thread exactly and run the two tests?

 

[Colseadoo1955]

I reviewed the carb rebuild post and believe I will redo the carb with a Mikuni OEM kit. I'm still not clear about testing and adjusting those pop-off numbers and suspect it has real issues there. Also, the ski bellows out quite a bit of blue smoke in the garage when running and due to poor ventilation really begins to burn one's eyes after running a bit. I'm thinking the motor itself may be in need of an overhaul (recommendations on a good rebuilder welcome). I ran it off of an outside fuel source to by-pass the fuel lines, selector valve, and tank pickup and that made no difference. I believe the carb is the problem. The new ones on ebay are all that BN40i which features a small external line that mine does not have. Would one of these fit and work on my GSI 717 motor?

 

[Colseadoo1955]

No, don’t blow out the selector. The go bad from the inside and have to be replaced. Lots of engines have been ruined from bad selectors.

Did you follow the carb rebuild thread exactly and run the two tests?

There is a set screw of some type on the side of the carb near the hose connections (see pic). What is that for and/or how does one adjust it?

 

[Gasngo]

That is a mixture or air screw or something in that arena. absolute verification on which carb you have is needed. If its off the motor then pics of top /sides Etc to help ID the carb then from there towards correcting the matter. I dont care about smoke Rt now just exactly what you have. Then on to the next step.

 

[POPPS]

That is the high speed screw,,they are normally closed,,to 1/4 turns out,, and normally have a plastic cap on them,

 

[Rabid]

A couple of years ago I had the same thing happen at high speed. I would be crusing along and get a slight stall like i felt when my thumb would tire holding the throttle. I went through the fuel system replacing hoses and cleaning the carbs. That fixed the problem. The slight cut out will make you think you are overreacting but you should heed the gut feeling.