I have a '93 650cc Jetski. I real jetski, don’t get me started on people who say they have a Jetski, but reallly have a 1200cc three person boat.
Anyway, the thing won’t run worth a crap. This spring, I took the carb off and found a layer of sand on the air side of the diaphragm. I figured that I had found the problem, so I bought a carb rebuild kit and replaced the diaphragm and all the gaskets. I put it back together and it fired right up! Great!
I took it out to the lake last Fri, put it in the water, and hit the starter. It started, ran for about a second, and died. I couldn’t get it to start again. I did smell gas while I was cranking it over, which makes me think it may have been flooded. But I drained the battery trying to get it started and ended up putting it back on the trailer and dragging it back home.
When I got home, I pulled the plugs and they both had good spark (the plugs are brand new). So, I pulled the carb again. I looked at the new diaphragm and it seemed warped. The old diaphragm was in good shape, so I put that one back on. I pulled the needle valves and they were clean. I blew through the valve seats and they were unobstructed as well.
I put everything back together and tried to start it. I got nothing. I shot some starter fluid into the carb, and it started. It will run with the choke on for awhile, then it starts to die. I can then open the choke and it seems to run well for 10-15 secs, but then it will die if I don’t choke it again.
I pulled the fuel lines out of the tank, and the pickups were clean.
I’m out of ideas. Is there anything else I can check?
Is your carb sonnected to the engine via a tube that it slides over? There should be an O-ring (or similar ring-type gasket) on the carb connecton that ensures an airtight seal so the combustion chamber can draw fuel through there. Without that, it seems like it might behave as you describe…able to run for 10 - 15 seconds (or less) on some starter fluid or at full choke, but can’t run normally.
You’ve eliminated enough varibales to suggest the fuel is not getting into the combustion chamber. Is the fuel getting into the carb properly? You open the throttle, ask for air and fuel and it seems as though it ain’t getting the fuel. It gets fired up when you deliver fuel via the starting fluid…but remove the hand- delivered fuel (the starting fluid) and then it doesn’t have any of it’s own.
Maybe the issue is the fuel coming into the carb, not the fuel going out of it.
BTDT and got the T-shirt to prove it.
First off is your ski a 2-stroke or a 4-stroke? Looking at the parts diagrams I am lead to believe that your ski might be a 4 stroke as the carb looks way different than the one on my '84 oil burner.
Anyway on my 2 stroke there was a set of stacked diaphragms on the side of the carb that acted as a fuel pump. The orientation of these diaphragms was critical. Get one backwards or in the wrong order, and you were screwed. (if you are having trouble picturing what I am talking about take the link above and change the model to a Kawasaki '84 550 jet ski) Also the carb used pressure pulses from the engine crankcase to power this fuel pump, and make the damn thing run. I found out the hard way that a blown shaft seal can give you a no start. Is there a separate fuel pump on your ski? If so I would suspect that. If your ski also uses crankcase pressure pulses, there is a spec for how strong they should be. It has been too many years, and I don’t recall what is was for my ski, but that is how I nailed down the bad shaft seals diagnosis.
Have you asked the local jet ski shop for their opinion? Often they are happy to answer questions, as they get to sell parts.
Have you done a compression test?
The fact that you have to use the choke indicates to me either a fuel flow problem, or a fuel metering problem such as a plugged jet. The next time you have the carb apart, blow out all the passages with compressed air (If you don’t have a compressor get a can of “air” at an office supply store) and take a fine wire and run it though the passages to make sure they are clean.
Rick, I was hoping you would stop by. I knew you were an automotive expert, but I didn’t know if you had experience with these things as well. It’s a 2 stroke. Keihin CDKII carb. It’s has a single diaphragm. No fuel pump, the carb uses pulses from the crankcase to run the diaphragm. I haven’t done a compression test as I don’t have the compression guage. I’ll see if I can find a spec on the crank pulses and check that.
I’m pretty sure it’s a fuel flow problem, but have checked everything that could be causing it. I’ve already pulled the needles out of the jets and blew them out. If you want a better look at my carb, use your own link to get to a '93 Kawasaki Jetski 650 SX.
Just had a thought. If the tank vent were clogged, could that restrict flow to the carb? I’ll have to look into that when I get home.
I pulled the vent line off the gas tank and blew through it. No obstruction at all. So, I figured I’d pull it into the driveway, hook it up to the garden hose (for cooling) and try and tune the carb. I choked it, and hit the starter - no starting fluid. It fired right up. After about 30 secs of idling, the idle started getting rough. I took the choke off and it just idled happily.
The only things I change were: I charged the battery (maybe the battery was low and not delivering enough spark while turning the engine over?) and I richened the low speed needle vlave about a 1/4 turn.
I’m taking it to the river in couple hours when it warms up a bit. If it doesn’t start this time, I’m gonna light it on fire and send it down the river!
brewha, if you have any more specific jet ski questions, feel free to PM me & I’ll give you my husband’s email. He races jet skis and would be happy to help you out.
Took the jetski out to the river today with high hopes of driving it this time. I tried to start it before getting it in the water. Hit the starter button and got a click-click but the engine wouldn’t turn over. Suffice to say I"m pretty fucking annoyed right now. It’s a gorgeous day and I"m still stuck on land.
I tore into the thing again. Pulled the starter and took it apart. There’s a strip of metal that connects the positve terminal of the starter to two of the brushes. It was broken in three pieces.
What to do now? I can drop $220 on a new starter. I can try to find a replacement for the broken piece (no luck yet). Or I can chop this thing up with an axe and burn it. I haven’t decided yet.