Carb fuel problem need help

[Mstratemann]

We bought a used 1999 Seadoo GTX limited which has few hours on it. It has the 947 two stroke engine. Because it had been setting for quite a while it would not start when .we bought it. Since buying it I have replaced all fuel hoses, vacuum pulse hose, drained the fuel tank and inspected the fuel tank. I have rebuilt the carbs using aftermarket kits once and twice I have used Mikuni kits. Have replaced needles and seat with Mikuni sets, set pop offs per factory to 23 pound, have set fulcrum arm height and installed new fuel filters. It does idle fine but acts like it runs out of fuel when you go to accelerate. I have also checked the accelerator pump per the factory manual and it appears to be fine. Also I have visually inspected the reeds and the look good. I am frustrated and need help carbs are set with zero on high speed needles and 1.75 turns on low speed needles. I am quite frustrated have worked on cars racing go karts motorcycles and jet skis very successfully but this one has me dumbfounded. Any suggestions?

 

[Mstratemann]

I have also installed new plugs and the power valves seem to not be stuck either.

 

[JeremyD615]

When you say you installed new filters, are they the OEM type, or inline filters? Sometimes the inline filters don’t flow enough to support higher rpms.

Is it shutting down or hesitating when you reach the point where it acts up? What rev range are you at when it happens?

 

[Sportster-2001-951C-Stock]

It does idle fine but acts like it runs out of fuel when you go to accelerate.

The low speed circuit of the carbs is clogged with corrosion debris, sounds like. Very common. Also ensure fuel flow is good, no inward air leaks in fuel system. The water/fuel separator cup gasket is a common leak point as is the manual reserve fuel selector valve.

 

[Mstratemann]

Thank you for your help. I am going to take the carbs off again. This time I will actually clean them after disassembling them in real carb cleaner that I use to clean car carbs. Up to this point I have only dissembled them and sprayed them with carb cleaner and blew them out but have not soaked them. The new fuel filter is a automotive fuel filter that can be cleaned and is made for a v8 engine. I doubt that is the issue.

 

[Mstratemann]

When you say you installed new filters, are they the OEM type, or inline filters? Sometimes the inline filters don’t flow enough to support higher rpms.

Is it shutting down or hesitating when you reach the point where it acts up? What rev range are you at when it happens?

It has done various things on the prior rebuild it ran but had to be transitioned to high speed with a little choke.

Now it gets up to rpm and then it dies at about 5,000 rpm. The choke no longer helps. I wonder if the piece that goes into the tank is possibly bad. All of the hoses were replaced by me with quality automotive hose made for this crappy gas.

I was not able to remove the fuel selector valve but I did replace the lines to it and I blew thru it with compressed air.

 

[Mstratemann]

The low speed circuit of the carbs is clogged with corrosion debris, sounds like. Very common. Also ensure fuel flow is good, no inward air leaks in fuel system. The water/fuel separator cup gasket is a common leak point as is the manual reserve fuel selector valve.View attachment 41624View attachment 41625

Is the water separator the filter that is mounted towards the front of the ski which has a fine mesh filter in it. Other than cleaning this has not been replaced.

 

[mikidymac]

Get rid of the inline fuel filter and replace the selector valve. Yes the strainer is the cup up front.

 

[JeremyD615]

Like Miki said, get rid of the inline filter and replace the selector valve. The filter is not doing you any good, and is a potential source of problems. The selector is a common source of air leaks, and that’s exactly what it sounds like you’ve got. The motor is going lean up top, and is starting to seize. I had similar issues with one of my skis recently, and it wound up being an air leak at the carb.

 

[Mstratemann]

Like Miki said, get rid of the inline filter and replace the selector valve. The filter is not doing you any good, and is a potential source of problems. The selector is a common source of air leaks, and that’s exactly what it sounds like you’ve got. The motor is going lean up top, and is starting to seize. I had similar issues with one of my skis recently, and it wound up being an air leak at the carb.

How do you remove the selector valve? It appears you pull off the knob and there would be a nut under the knob to take off.

 

[Sportster-2001-951C-Stock]

On my valve, the knob has a decal applied over the head of a phillips screw fastening the knob to the shaft.

 

[JeremyD615]

You have to pry off the plastic cover in the center of the knob to reveal the retaining screw, then you can remove the knob. Underneath is a nut that hold last the whole thing on the hull.

 

[Mstratemann]

You have to pry off the plastic cover in the center of the knob to reveal the retaining screw, then you can remove the knob. Underneath is a nut that hold last the whole thing on the hull.

I ordered the parts this morning. Crossing fingers.

 

[Mstratemann]

Thanks for the advice. I finally got my problem fixed. Tried fuel selector valve and replaced factory filter and o ring but that did not fix it.

 

[Mstratemann]

So then for the forth time I removed the carbs and went thru them again. I found the small hose for the accelerator pump had gotten pinched and cut. Also when pulling the carbs off I either lost the intake gasket or I never installed it previously, I think it was lost but could not find it as it must be under the engin were I could not reach. I pulled carbs apart and soaked each main body in Berryman carb cleaner after complete disassembly. Then rented them off with water and blew them out with compressed air. Reassembled and reinstalled them. Also removed the aftermarket inline fuel filter. I set main screw at 1/4 turn and low at 1 3/4 turns out. Now it runs like a champ and I also put on new intake manifold to carb gasket.