1999 Seadoo SPX jerking

[Ckrawiec]

Ok cool, thanks for the advice. Will work through all of these. The battery is brand new, so will start with the other tests

AHHHH....brand new batteries are no guarantee that they are sound.....you don't know how long they have been sitting around. A quick "load test" at the auto parts store [free] will tell you if the battery is "sound".....a load test will stress the battery (with a resistive load , load tester will start heating up) and can quickly diagnose that all battery cells are working, etc.....TRUST NOTHING!

And, not for nothing.....skis really need to be in the water to properly dial them in.....skis running on trailers on a hose only tell us that they start......sitting in the water puts a load on the engine and that's when you can really diagnose problems.....(sitting on a trailer in enough water is OK too).

 

[RTW]

How would I know the battery is strong enough? What should it read on the load test?

 

[RTW]

You need a good compression guage....Harbor Freight compression test guages are JUNK btw.

Take spark plugs out, thread guage in, start the ski...the pistons will pump and the guage should take a measurement. Do both sides, write down what you get...both cylinders should be roughly equal (150 psi is close to ideal - I believe...or something in that neighborhood..) test a couple times

The advise you have received so far is right on:

1) Rectifier/Regulator could be a culprit (relatively cheap and easy to test and/or replace)
2) CARBS - my money is on the carbs......the root of MOST evils in these skis....they are persnickity.....they need to be dialed in just right.....using only GENUINE MIKUNI parts (everything else is a fools folly).....MANY have chased their tail with non-mikuni parts and eventually capitulate into MIKUNI parts (and saved their sanity) - BEEN there ->done that.
3) BTW: These skis need a good strong battery to get things going, so ALWAYS START with a known good, strong, load tested battery.

For the compression test, must I do it with jetski cold or warm it up first or does it not matter? Is it fine to do test on trailer out of water?

 

[mikidymac]

Compression test should be done on a cold engine, out of the water, plug wires grounded with the fuel off and the throttle held wide open.

 

[RTW]

Hi, an update. I did compression test and got the following results:
Front cylinder = 135
Rear cylinder = 140

I purchased a new coil and replaced.
Took the ski to the dam today, problem is still there. I tried disconnecting red wire from voltage regulator and it didn't fix the problem.

Will have to pull carb off and check it

 

[fzrace]

What color are your fuel lines?

 

[RTW]

I changed them a few years ago from the grey lines

 

[RTW]

Hi guys, an update. I ordered a "back to oem" rebuild kit from OSD parts and it arrived on Friday. I went through the carbs cleaning them according the the rebuild thread. Started with the MAG carb and then went onto the PTO carb replacing the old parts with the new ones from the kit. When i got to the PTO i thought i was supplied one part short and contacted OSD parts to tell them but they said that part shouldn't have been there and that they supplied me the correct parts. Is it correct that the PTO carb doesn't have a diaphragm on the fuel filter side as my carb had one when disassembling, do you just tighten the cover over the formed o-ring?

 

[mikidymac]

The PTO uses no diaphragm, only the formed o-ring.

 

[RTW]

The PTO uses no diaphragm, only the formed o-ring.

Thanks, I have removed the diaphragm now. Tested the carb now with a pop-off gauge to check it’s still holding pressure. Put 10psi into it but within a couple of seconds it slowly drops to zero. What would be the cause? Could it be that the formed o-ring is not sealing properly? Are the bolts that are used to tighten the cover onto the formed O-ring meant to have washers? I see in some diagrams it looks like there is meant to be washers, my carb didn't have any washers. Wondering if maybe its not tightening enough?

 

[mikidymac]

They should have washers.

Try spraying the outside body of the carb with soapy water and look for bubbles at any leaks.
If not it could be leaking inside like at the needle seat o-ring.

 

[RTW]

Used washers and seems to have worked. It’s no longer leaking and is holding pressure. Will install carbs on the weekend and hopefully it sorts the issues out.

 

[Joey White]

Are you sure there is no leaks around the gas tank, fuel lines, or fuel selector. That might be just letting air in to the system causing it to do that.

 

[RTW]

I don’t think so. Just rebuilt the carbs. Will install them back on the ski over the weekend and see if it’s solved the problem. I think it was the carbs though that were causing the problems. Was rebuilt by the Sea-Doo agents but when I did it myself now, I saw there was a diaphragm in the PTO carb that shouldn’t have been there and I think they used the wrong springs because the pop-off pressure was too high. Used the springs in the OSD back to oem kit and now pop-off is spot on.

 

[RTW]

When going to install the carbs this evening I noticed the ski had a pool of oil in the bottom of it. It’s been standing for months so not sure why. I have looked to see where it’s coming from and it looks like it’s coming from the breather at the top of the oil tank and has been leaking onto the fuel tank and then to the bottom of the ski. Anybody know what is the cause of this and how I solve the problem?

 

[Joey White]

How full is the oil tank?

 

[mikidymac]

Typically it’s the rubber grommets on the bottom of the oil tank. But if you overfilled the tank the check valve on top could leak.

Also I hope your tank is just stained and you aren’t running blue oil.

 

[RTW]

The oil tank when I’ve leveled the trailer is just under full. It has been standing with nose down. The fitting on top of the oil tank with the check valve is more towards the front of the oil tank so maybe with it at the angle it was over full? The oil tank is just stained blue, as per the picture you can see the purple oil on the fuel tank. There was a bit of oil on the grommet underneath the fuel tank but it’s not dripping or running, was just a little wet

 

[Joey White]

Sounds like it's just dripping out. Nothing much to worry about if that's the case. Just don't fill it up all the way next time you put oil in it.

 

[RTW]

Thanks. Does the oil light work on oil level or has it got a pressure sensor somewhere?

 

[mikidymac]

The oil light is just a float switch in the oil tank. Tank gets low, the float drops and completes the circuit turning the light on.

 

[RTW]

Hey guys, just an update. Took the ski out to test over the weekend and she ran perfectly. Carb rebuild sorted it out.