1996 GTS ran perfect for 2 hours and now stalls when given throttle

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YourLocalKoko

New Member
Hello guys! I'm new to the whole jet ski thing as I just got two of these 1996 Sea Doo GTS and they are my very first skis. I decided to take one out yesterday and have a little fun with it. I drove around at WOT majority of the hour and a half with no problems at all. Idled fine, took off fine, no hesitations whatsoever (in salt water). However, all of the sudden I just started loosing power. The ski began to drive as if it was running out of gas (Pummmmm Pummmm Pummmmmm Pummm), but would still drive at a relatively good pace except it would sputter,(once again just like I was running out of fuel). The issue slowly got worse to the point where I ended up having to idle back to the dock because giving it any throttle would kill the engine but idling was just fine.

When I got back to to the dock I discovered that fuel tank still had plenty of fuel left (half a tank), and nothing was sucked into the impellor, or intake grate. The selector switch is bypassed and I'm pulling directly from the Reserve Line. Plenty of oil in the Reservoir, and oil pump just recently replaced. I have the black fuel lines and not the gray problematic ones. Compression on both cylinders is perfect (tested by mechanic)

I tried adding some sea foam to the fuel, inside the spark plug holes, and into the carb from the top without removing it from the ski letting it sit over night and ran the engine without the plugs in as per the sea foam instructions. I also tried replacing the spark plugs, and inline fuel filter to no avail. Still after doing all of this the ski still idles perfectly fine and even attempts to act like it is going to take off but then just stalls and dies. ( Not sure if this is any help but To keep it from dying I discovered that releasing the throttle and pulling the choke in and out a few times quick saves it and get its idling.) I tried letting it idle in the water for 20 mins to see if I just needed to give it a little time or something but that didn't help. Removed hoses from the carb and fuel is definitely getting TO the carb. Now out of it I have no clue. Half of the tank was about 20 day old gas and then I filled the rest of the tank with brand new gas so I think I'm good there.

I don't think its the carb just because of how sudden it was. How could something obstruct it that fast!? Anyways, any advice would be greatly appreciated, and thanks for reading and helping!
 
It is Tuesday so I may be responding too late. Sounds like typical trash in the jet. It will occasionally clear itself or with seaform, etc..., but you will most likely have to clean out the carbs. Also pretty old ski and new to you with maybe no maintenance records (usually not). If you are up to DIYing it, just take your time and pics help also. Lightly screw in mixture screw and count the turns in. set them back to where they were and start from there. lots of times that works without adjustment. Don't overthink it. it's a simple little puzzle. GOOD LUCK!!!!
FYI: fuel treatment or non-ethanol fuel is a must on older skis.
 
It is Tuesday so I may be responding too late. Sounds like typical trash in the jet. It will occasionally clear itself or with seaform, etc..., but you will most likely have to clean out the carbs. Also pretty old ski and new to you with maybe no maintenance records (usually not). If you are up to DIYing it, just take your time and pics help also. Lightly screw in mixture screw and count the turns in. set them back to where they were and start from there. lots of times that works without adjustment. Don't overthink it. it's a simple little puzzle. GOOD LUCK!!!!
FYI: fuel treatment or non-ethanol fuel is a must on older skis.
Thank you so much you were 100% correct! A simple cleaning of the carb made it run a million times better. Now the only problem is that it runs lean on hard turns and takes a min to go back to full speed so I think doing what you said and adjusting the mixture screws should 100% resolve the issue. THANK YOU AGAIN
 
Please take a compression test,,,during some of those lean moments,,,you may have Partially scored a piston.causing power loss.
Is there anyway of testing this not on the water? I think my issue might be a bad venting valve for the fuel tank causing a vacuum, and thus a lean state. I’m waiting on my pop off tester to confirm/deny this theory.
 
happened to me once,,,but opposite to yours,,,ski always stored out in the sun,,,would run very very rich,,,the exterior vent valve,,,would not open,,,the back pressure opened the needle in the seat, causing the carb to flood…replaced the the valve,,,problem solved.
 
happened to me once,,,but opposite to yours,,,ski always stored out in the sun,,,would run very very rich,,,the exterior vent valve,,,would not open,,,the back pressure opened the needle in the seat, causing the carb to flood…replaced the the valve,,,problem solved.
We might have the same problem then, except mine is the other valve. Thanks for the help!
 
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