94 seadoo spi starts but dies when throttle applied

[Cbitetti18]

Hey guys. I am a new ski owner here and am looking for some answers. I have a 94 seadoo spi that has been sitting for a few years. I put an ignition coil in it and it fired right up. had a full day of fun on the lake and the next day we took it out and while going fast it died out as if I pulled the key. it started back up and died again after about another 30 feet. I have since rebuilt the carb, a rebuild kit from the marina, blew it out and cleaned it with carb cleaner. reinstalled and the thing fires up great now but boggs out and dies as soon as i give it throttle. This is being done on land. I did not do a pop off test on the carb because i do not have the tools. I left the original spring inside. the gray fuel lines have already been replaced.. Let me know what you guys think its definitely a fuel air mix issue I just don't know how to figure it out.

 

[SigEp368]

If it was running before the rebuild, and you used the same spring and arm, then the pip-off probably does not need adjustment.

Assuming it was an Mikuni kit and you followed all the steps in the carb rebuild sticky, then it sounds like an air leak. Were you able to pressure test the carb and/ or the fuel system?

Double check all your connections, and your fuel bowl gasket. Pull your vent filter and see if it is has unidirectional flow into the tank, otherwise you could be vapor locking.

if none of that works, connect your main fuel line directly to your carb inlet. If you use your reserve line, you might want to add an inline filter, just in case you suck crud up from the bottom of your tank.

good luck!

 

[Cbitetti18]

Thanks for the help. No I was not able to pressure test the fuel system or carb. But question where is the fuel bowl gasket? Also is the vent filter the small line that goes out the top of the ski? It could be vapor locking. And how do I know which is the main fuel line? Thanks again.

 

[Saludadoo]

You have a fuel filter under the dash were the key is. above the fuel tank. my 95 SPI the line to the carb is the line facing the front of the ski going to the carb and the return line is toward the back.
There is a little filter inside the carb and the water filter under the dash.
sounds like you sucked up trash in to the filter on the carb.

 

[Cbitetti18]

Hey yes I have cleaned out the filter under the dash. I also completely rebuilt the carb and replaced the small filter inside. Please help

 

[Seadoo Tuner]

I had a similar issue previously with my SPI. It was an incorrect spring and popoff was too low. I'd make a popoff tester (cost $10 to diy and is easy) and make sure your popoff is correct first.

 

[SigEp368]

Agree with seadoo tuner, having a pressure tester is helpful for performing a couple routine maintenance taks, whether its pop-off, carb, oil system, fuel system, or jet pump housing tests. its worth getting one.

if you cleaned the filter bowl recently, did you get the square o-ring seated back properly? i have been messing with mine all summer, and have been through multiple gaskets. i keep spares around now, cause that little $5 gasket can ruin your weekend quick (and its always special order item).

i would think vapor locking would only happen in a high demand scenario, but if you suspect it, you can always loosen the gas cap and see if that corrects the problem.


good luck!

 

[Cbitetti18]

Hey guys I had a friend of mine who is good with skis come over and help diagnose the problem. He thinks it is carburetor related so he took it home with my new kit and all the old parts, rebuilt it again and he tested the pop off. We put it in and still the exact same thing. It starts up great but as soon as throttle is applied it shuts down. Come to find out I did not get an OEM kit like I thought so I have since ordered a Mikuni kit and I’m really hoping this does the trick. If there’s anything else I should try please let me know! I have already replaced the fuel lines pulse lines and bypassed the fuel selector. All the same result.

 

[mikidymac]

Fuel strainer housing o-ring?

 

[Cbitetti18]

Did not check that but am I correct by putting the carb feed line directly to the reserve port on the fuel tank doesn’t that bypass the fuel selector and the fuel strainer ?

 

[mikidymac]

Yes it does bypass it.

 

[SigEp368]

It definately sounds like it is starving for gas when stressed. Does it run any better if you manipulate the choke during mid to full throttle?

When bypassing, do the other hoses need to be plugged, or the tank selector switch be set to OFF, in order to allow tank to pressurize?

Is there someway to ensure the fuel pump is producing the right output? For example, what type of flow is expected from the return port of the carb?

Would it be possible to check the fuel pump seal by pulling a vaccum on the pulse side using brake bleeding tool?

 

[Cbitetti18]

I have not actually tested the fuel pump I will need to buy a gauge to do so. I have a mikuni kit on the way and was going to try that. And if the pump output is bad then what? Can I just buy a complete new carb? Or pump? I know they’re lifetime use but literally all I wanna do is be out on the water. And I’ll do whatever to make it happen. I’m not sure if I need to plug the other lines when bypassing but perhaps I could try it. And no manipulating the choke does not help it still dies right down. Also tried putting about a tablespoon of gas directly into the carb and that doesn’t help either

 

[mikidymac]

No, you don’t test fuel pressure.

Follow the carb rebuild sticky above and you’ll be fine.

 

[phoenix02]

Is there a sticky for fuel system function that explains how the fuel system works and why air leaks are so detrimental for older 2-strokes?

 

[SigEp368]

For carbs, there are the stickies that Mikidymac and Bills86e created in this forum, and you can check out the Seadoo Source website.

 

[phoenix02]

Lots of carb advice and good thing since that is a usual suspect. But beyond that, leaky fuel/water separator, fuel selector switch, etc... It would be good to understand the theory of why leaks in those create problems at the carb. If they aren't leaking as proved by fuel 3 psi pressure test, and the pop-off pressure and fuel pump pressure tests good, but the ski still has problems, the theory might help a lot.

 

[phoenix02]

Reviewed the carb sticky again. I didn't know that the mylar check valves were directional! I don't remember seeing the blue stripe when I installed them. Should I rebuild my carb again just to make sure my fuel pump valves are installed correctly? Installing those valves is the worse part of the job. Argh... Just did mine 2 yrs ago but always having problems starting in the water and getting full power at WOT. The fuel pump does hold pressure at both ports.

 

[phoenix02]

I have not actually tested the fuel pump I will need to buy a gauge to do so. I have a mikuni kit on the way and was going to try that. And if the pump output is bad then what? Can I just buy a complete new carb? Or pump? I know they’re lifetime use but literally all I wanna do is be out on the water. And I’ll do whatever to make it happen. I’m not sure if I need to plug the other lines when bypassing but perhaps I could try it. And no manipulating the choke does not help it still dies right down. Also tried putting about a tablespoon of gas directly into the carb and that doesn’t help either

Where are you located? If you are in N. TX, I have a gauge you can borrow.

 

[mikidymac]

Reviewed the carb sticky again. I didn't know that the mylar check valves were directional! I don't remember seeing the blue stripe when I installed them. Should I rebuild my carb again just to make sure my fuel pump valves are installed correctly? Installing those valves is the worse part of the job. Argh... Just did mine 2 yrs ago but always having problems starting in the water and getting full power at WOT. The fuel pump does hold pressure at both ports.

Yes, and if they didn't have the blue stripes the they were not genuine Mikuni.

 

[phoenix02]

Thanks Mikidymac. Would you clarify your carb sticky for me? On the step #4 where you clean the " three small holes and one large hole that meter fuel into the carb at idle and just off idle", where are you spraying the cleaner? You've got the low speed screw in that hole so it's not there. I can't figure what hole accesses those four holes.

 

[mikidymac]

You remove the small brass pilot jet and spray there. If you don’t have the LS screw in a turn the carb cleaner will just go out the screw hole instead of being forced through the three little holes.

 

[Cbitetti18]

No, you don’t test fuel pressure.

Follow the carb rebuild sticky above and you’ll be fine.

I have rebuilt the carb again with OEM mikuni parts. I still have the same exact thing. The ski starts up good but dies with throttle. does not matter how i manipulate the choke and I have cleaned out the selector and the fuel filter and even tried bypassing them both. all new lines also. I thnk now i may be the rotary gear. like its not able to spin the engine. But I am wondering should I be able to spin that by hand? I know i need to get the piston to TDC before doing the timing.

 

[phoenix02]

Are you talking about the brass gear for the rotary valve? The valve should not have any play in it if your gear is good. If it's stripped, it will have moved from timing so that should be your second clue if the valve appears tight.