2000 Sea-Doo GTI Won't Run Properly - I want to blow it up!!

[betzgb]

So frustrated with my 2000 Sea Doo GTI. Long story of troubleshooting but still no dice! It ran fine the first few outings over the summer then trouble hit. I went to the gas station and filed up the tank then went to the ramp to put in the lake. Ski started fine and backed off the trailer and everything went great, responsive, normal sounds, etc. After about 2 minutes I began to idle to a the dock to tie up in a no wake zone. About halfway to the dock (100 yards away) the idle became a little rough and so I gave a little more gas, but there was no throttle response. It just bogged when you open the throttle. It would start just fine and idle (a little rough) but at full or part throttle it just bogs and won't develop any power or get above an estimated 1500 RPM. Ski won't get on plane at all. After a few minutes of trying to troubleshoot I idled back to the trailer and took it out of the lake. There was not excessive smoke. Here began the troubleshooting saga...

Note: I replaced all the gray fuel lines and rebuilt carb about 3 years ago and it has run perfectly up until now.

First thought was bad gas since it ran great before and I just filled up before trouble hit. I took off the fuel supply line and ran it to a small bottle of fresh gas. Same issue.
Inspected the impeller and everything looks good there. No damage on the impeller and still normal clearance between impeller and sleeve.
Checked for spark. It is present based on a spark tester light but replaced the plugs and ignition coil/wires just to be sure. Did not help.
Tested compression with plugs out and throttle wide open. Both cylinders are around 133psi. I think that is ok.
Then I rebuilt the Mikuni carb with a Mikuni kit. It seemed to get worse now but I have been trying to test it with the air intake and suppressor off just so I can see and adjust carb more easily. Does that matter? Now the ski will only start after holding the start for about 30 seconds and part throttle open. It then runs for about 15-30 seconds and dies. After starting and starting again it will finally fire and run about 15-30 seconds spewing lots of fuel and oil from the exhaust when it finally does fire. In fact I noticed the 2 stroke oil reservoir level was only half full and I think that is pretty high consumption considering the low use this season. Also, if I take out the plugs (plugs are very wet) and give a squirt of starting fluid into each cylinder, reinstall plugs, and hit the starter it still won't fire. There is fuel in the carb (I can see it from the accelerator pump stroke) and it comes out of the fuel return line. I am now officially at a loss on what to do next (other than roll a grenade under it).

Thoughts on what the problem could be? Thoughts on what tests I could try next? Thanks

 

[mikidymac]

Sounds like your needle and seat are leaking flooding it out. Have you replaced it?

You used genuine Mikuni kit?

I would also replace the fuel selector and strainer to be safe.

 

[betzgb]

I did replace the seat/needle with a Mikuni kit. Maybe I need to reopen the carb to see if it is not seating for some reason. As for the fuel selector and strainer I am think that is not related since I bypassed those and used a jug of

 

[mikidymac]

The spewing of fuel and oil out of the exhaust and having to hole the throttle open to get it to start sounds like it is flooded to me. I had the same issue with an XP that had the needle and seat leaking.

WIth the carb together plug the return hose and plug that fitting with your thumb and use your pop off tester to put air into the fuel feed fitting on the carb it should hold 10 psi indefinitely. If it doesn't you have a leaning needle. You can do this with the carb still installed and hoses off.

 

[betzgb]

Thank you! will give it a shot and let you know

 

[IDoSeaDoo]

When you rebuild these carbs, be careful where you set that needle. I've had it to where the needle will hold pressure and pop-off correctly, but when I installed the cap, it ever-so-slightly pressed on the diaphragm against needle-arm. This caused the engine to flood with fuel. It was more a problem when it was sitting or starting than running, so I don't think you have this issue. Just something to be aware of when you're rebuilding the carbs. Before you put the diaphragm and cap on, you can give the needle a quick spray of WD-40 and perform a pop-off test with it all assembled. You should have similar results as with the carb apart.

Have you lost any more oil since last time? I wonder if you didn't lose a rotary valve or crank seal. If you're dumping oil in there, you'll also get wet plugs, even a hydrolock if you get enough oil into the combustion chamber. It'll also smoke like a skinny dude vaping when it does fire and spew tons of oily shit out the exhaust.

 

[betzgb]

Hey guys, it holds 10 psi if I plug the pulse line inlet and return lines and supply air to fuel inlet. Without plugging the pulse line inlet on the carb it does not hold pressure in case that is unexpected. I took the carb off and performed a pop off test a few times at it seems to be ok around 34-35psi. I put the carb back on and it is super hard to start still. I can finally get it running holding the throttle part way open. Holding the throttle part way and not moving it the engine rpms surge then slow near stall then surge again then nearly stalls. Light smoke from the exhaust. Not I am running the carb fully exposed (without the fire suppressor) in case that matters. I also notice a slight blowback of fuel from the carb throat when I do give squeeze the throttle and the accelerator pump is giving a shot of gas. Other thoughts? I am seriously going to roll this thing off a cliff and be done with it!

 

[andrewterri]

little smoke from the exhaust is okay. did you check your oil injection pump or are you using premix? did you try doing the pop off test after everything is assembled like IDoSeaDoo suggested? I am just throwing this out here until the experts get on, but with it loading up on fuel is has to be in the carbs assuming your ignition system is good. Have you changed plugs and trimmed the wire cap? are you sure your getting good spark? if carbs are good then the only other way it could be loafing up on fuel and not starting is the engine not getting adequate spark.

 

[mikidymac]

There is your issue. You shouldn’t be leaking anything at all through the pulse nipple.

 

[betzgb]

Just to confirm, I should be able to apply pressure to the fuel inlet and it should not escape through the pulse nipple on the carb?

 

[mikidymac]

Correct. You have a bad gasket or the clear film. Did you use all the new parts from a genuine Mikuni kit and clean all the old gasket off?

 

[betzgb]

Or perhaps "someone" failed to install the clear film... Damn! I took the carb back apart and got it right this time, then installed on the sea-doo and damn if it didn't start right up! Idles pretty well and decent throttle response on land. So now the question becomes - did I solve the original gremlin which triggered the carb rebuild? It was behaving about the same on land last time but in the water it would simply bog at part or full throttle. I guess there is no way to test except get it back on the water and give her a go. Will update progress tomorrow!

 

[mikidymac]

Great that you found something so obvious and easy.

 

[betzgb]

Just when I was feeling lucky... I took the Sea Doo to the lake for a water trial and it didn't go well. It started right up but as I gave it more throttle it just bogged and never developed power. Back to the original issue it seems, though there was a lot of smoke also pouring out. After a couple of starts it became more difficult to start and eventually would not start at all due to flooding. So I think I am fighting potentially 2 different problems. 1.) fuel is just pouring into the engine and only when I hold it at mid throttle can I get it to run barely. What would cause the valve to not re-seat? Tried two different ones and just doesn't want to re-seat after pops off. Is there such a thing as too much pressure in the fuel lines? 2.) I am wondering if I am getting too much oil in the mix (not using pre-mix) as the oil tank continue to lower, though not while just sitting. Could that cause my bog too?

 

[andrewterri]

if will bog if you are injecting to much oil. Did you check the oil injector? there are two marks on it, one mark on the arm and one mark on the housing itself. the two lines should line up. if you can not see it use a mirror and flash light and make sure it is set right.

 

[andrewterri]

what size needle and seat are you using? did you check the pop-off after pump everything together when you fixed the pulse diaphragm? did you check the N/S arm to make sure it is not sticking up to high?

 

[betzgb]

As for the oil injector - I will have a look at that. The two marks should line up at full throttle or at idle? As for the carb, I am using a 2.0 (what I found in the carb originally). I did use a razor blade to make sure the N/S arm was flush with the housing. I checked the pop off after everything was assembled and after it pops off it doesn't want to re-seat.

 

[andrewterri]

the oil injector marks should line up at idle. With the ski off just use the mirror and look at it. once you see it lined up, while still watching your marks, give it full throttle and release it and see if that arm is hanging up or traveling smoothly. One of the more knowledgable members will have to chim in on this, but are you sure you have the check valves installed correctly? were they setting flat with no trash or debris under them?

 

[betzgb]

Everything looks good on the oil marks. They do line up at idle and the arm travels smoothly at full throttle and release. I think the check valves are good as I put a hose on the inlet nipple and I can blow but not suck and the opposite is true on the return line nipple. I am thinking about dropping $210 on a replacement carb from osdparts.com just to rule out but what a waste if I am overlooking something stupid. Also, not sure it is worth it on a 2000 GTI...

 

[IDoSeaDoo]

Can't believe you got it to start at all without that pulse diaphragm (clear film). That's what makes the fuel pump work in the first place. It definitely sounds like you're getting way too much fuel. Is it a single carb or dual? Perhaps your accelerator pump is delivering too early? Guys, is there an adjustment on that? I haven't messed with those much, but when I tried to use accelerator pump carbs on my 97SPX (didn't originally come with them), the ski ran like total crap. Is there a way to adjust how much fuel it delivers, or when? What are your needle settings at? have you tried screwing in your Low Speed adjusters to make it a bit leaner at the bottom end?

 

[betzgb]

Single carb setup. It does have an accelerator pump but does not appear to be adjustable, not acting strange. Nice smooth/small stream coming out when applying throttle. I can't prove it, but it really seems like the fuel lines remain under pressure and when the needle unseats it never reseats and it just starts dumping fuel in the motor. Lots of gas/oil volumes dripping out of exhaust while trying to start it. Is there some kind of vent that could be malfunctioning causing fuel line pressure? When I take off the fuel line from the carb (after trying to start for a while) a fair amount of gas continues to pour out of the line even with it higher than the tank.

 

[IDoSeaDoo]

Unscrew the fuel tank cap and see how it runs. You do have a fuel tank vent that might be clogged. There is a 1-way valve to prevent pressure from building above 3psi. Fuel dripping from exhaust is a definite sign of a super rich condition.

 

[betzgb]

Actually one more test I forgot to mention... I took a small bottle and filled it with gas (about 2 cups) and ran a hose from that to the carb inlet. I left the factory return line in place to the tank as normal. It still was getting way to much gas so that kind of rules out fuel line pressure unless there is a way pressure is pulling through the carb. I went through the two cups of gas in about 2-3 minutes trying to get it to start.

 

[IDoSeaDoo]

I seem to recall reading somewhere that those accel pumps were used because people were loading up (building up too much fuel in the crankcase) idling through long no-wake zones. Hence, they increased the pop-off pressure in the carbs and relied on the accel pumps to get them back up quickly. Maybe try putting in a stiffer spring and run the carb at the highest range pop-off pressure. Pop-off pressure works in conjunction with the low speed adjuster and is resonsible for controlling from idle to about 1/3rd throttle. If your pop off is low AND you have accel pump, you could be overfueling. Keep in mind, every time you press the throttle, you squirt more fuel in there. Have you tried slowly squeezing the throttle to bring the RPMs up and clear out the motor?

 

[betzgb]

Thinking of another test... Can I take some 40:1 premix and run the motor on that and pinch off the oil supply line to rule out that my hard starting isn't related to excessive oil being injected into the motor? Recall my original issue before rebuilding the carb was no power under part or full throttle. It just bogged down completely.