Stall issue 1996 seadoo GTX

[dabernathy8181]

I have a 1996 GTX with the 787. The ski was parked for about 6 years before I got ahold of it. I pulled the tank l, replaced the fuel lines, put a new filter between the tank and carb. Pulled the carbs and rebuilt with genuine mikuni parts(I learned my lesson with vertex rebuild kit and Mikuni is all that can be trusted). I brought the ski out for a test ride 2 weeks ago. It's fine forever, will run for a few minutes with partial throttle, but if you high rev the engine, it acts as if the power was killed. Took it home and tested the rectifier it was pushing 16v to the battery at 5500rpm. Replaced the rectifier and tested at 5500 and 14.6ish was max voltage to the battery. I was steered to the rectifier from somebody on another forum. Not a bad call but I took another trip to the lake this weekend. Same exact scenario, I can't get more than 5-10seconds of throttle response before the motor stalls or goes to near stall if I let off the throttle quick enough. My compression may be a little low but I'm checking with HF gauges so not exactly accurate but both read 110 on it. My 01 GTI reads 100 on it and it runs perfect so I think my gauge is just inaccurate. Any ideas?

 

[dabernathy8181]

Battery is charging at 13.8 at 5500rpm. Checked on the hose at the house and runs perfect on the hose. The only part of the fuel system I didn't replace was the selector valve. I'm still leaning toward electronic issue.

 

[dabernathy8181]

New thought that might relate to this. I'm prefixing as the injection pump was not salvageable and the previous owner was prefixing as well. They left the pump on, I removed and blocked it off. When I replaced the lines I put and inline filter before th carbs. Running one of the marine filters that go on most typical outboards and looks similar to the oil filter if it's not the same one. Could this restrict fuel flow?

 

[JC-SUPERJET]

Pre-fixing? So the Oil Injection Pump was removed and now are PRE-MIXING the Fuel?

Did you leave the Oil Tank connected to the two Rotary Valve Gear Shaft Oil Bath Fittings to lubricate the internal Rotary Valve Gear Shaft?

 

[etemplet]

Get rid of the In-Line filter. The water seperator is all you need. In-Line Filters cause nothing but problems exactly as you describe and worse. I've sat in my "thinking chair" trying to figure out the reason but the ski doesn't care what I think. LOL Take that crap off the ski.

 

[dabernathy8181]

Pre-fixing? So the Oil Injection Pump was removed and now are PRE-MIXING the Fuel?

Did you leave the Oil Tank connected to the two Rotary Valve Gear Shaft Oil Bath Fittings to lubricate the internal Rotary Valve Gear Shaft?

Yes, Premixing, sorry for the typo. I believe my phone doesn't like the word Premix so it changed it every time I typed it and I didn't catch it. Going to remove the inline filter as etemplet suggest and replace the selector valve. might do one at a time just make sure if either was the problem I can pin point.

And yes the second line is still hooked up, the injection system is all that was disconnected. I have read quite a bit about premixing verses the oil injection and some people are avid that the only way to save the motor is to premix where as others are avid that the injection system in Seadoos are nearly bullet proof. I have a GTI with the system operational and I have the GTX with it deleted. I think both ways work but the premix to me is more of a hassle.

 

[JC-SUPERJET]

Oil Injection is ideal and best as long as the Oil Injection Lines are replaced every couple of years.

Because they supply the optimum Oil Quantities for each RPM range.

The Oil Injection Pump never fails because it is lubricated by a constant Oil Bath from the Oil Tank.

And even if the Oil Tank was empty, the Engine would fail before the Oil Pump ever does.

The Oil Injection System has gotten a false undeserved bad reputation from People who never replace the Oil Injection Lines.

Also, some Racers delete it to customize they're own Engine lubrication supply and take away a tiny parasitic horsepower drag on the Engine. Many see the Racers delete them, so they copy. Monkey see, Monkey do.

P.S. There have been reported rare cases in which the Oil Injection Spigots in the Intake can clog as they have built-in Ball Check Valves; probably due to use of incorrect Oil or extended non-use period. Or the infamous OEM Gray Tempo Lines.

 

[POPPS]

Sounds like carb fuel starvation,,,has symptoms of pop off being too high and or the pilots being too small or the pilot bypass holes being plugged.

 

[Lothsahn]

Harbor freight gauges are worthless. You have no idea if you have good or bad compression with those. It's because the check valve for the gauge is at the gauge, not the end of the hose.

If you want to check compression, borrow to get a good gauge. Napa and Autozone will often let you rent or borrow the gauges.

Looks like you've done most of the right things. Couple other things to check:
1) Remove the inline fuel filter. It can restrict fuel supply and cause exactly these kind of problems.
2) Consider replacing or bypassing fuel selector valve temporarily. Probably not the cause, but a restriction there if the valve fails can cause problems.
3) Empty the water separator and ensure it doesn't have a clogged screen. If it's clogged up, you could have a fuel delivery problem there as well.
4) If you pull the choke a little as you give it gas, does it run better?

When you rebuilt the carbs with genuine Mikuni, did you spray out all the venturi and ports and such with carb cleaner? You sure nothing's plugged or clogged there in either carb? Also, did you KEEP the springs that came with the carbs, or did you use the new springs that came in the rebuild kit? The springs that come in the rebuild kit are the wrong strength and will cause it to run badly. You have to keep the original popoff springs...

By the way, if the rectifier is failing, it shouldn't *quit*. It'll just refuse to rev and start surging beyond a certain RPM. The more the rectifier fails, the lower the RPM before it surges. But it was a good thing to eliminate.

I agree, premix is a hassle. Once you get it running right, you could hook it back up, but first things first..