08-13-2007, 10:22 PM #1
96 SL900 only starts when feathering throttle and runs slow
Just got this thing on the water yesterday for the first time after purchasing it with a completely rebuilt motor (crank, rods, pistons...etc). Started right up and ran awesome for about 15-30 minutes until I let off the throttle and it died. Only way I can start it now is to hit the throttle a few times, hit the start button and then feather it to between half and wide open throttle. If I let the throttle go, it dies. At WOT it runs at 3800 rpm and very slow speed. I checked for spark and have it just fine on all 3 cyl. I have not yet checked compression. The gas in the tank was very old and thought that I could just run it out. I am thinking that my problem may be in the fuel system but don't know where to start. Do you guys think that maybe that old gas gummed up the carbs somehow? If so, can I clean those myself or should I send them to Randy @ Watcon and have him rebuild them?
Any other ideas are gladly appreciated.
OH! One more thing, that old gas DID have oil in it @ 25:1 from what the guy I bought it from said if that is helpful.
08-13-2007, 10:32 PM #2
Try changing the plugs real quick. If that doesn't help clean those carbs. You can send them to Randy and for 40 bucks a whack plus some parts he'll rebuild them. He'll set the pop-off, synchronize and of course check shafts/bushings etc.
08-13-2007, 10:56 PM #3
Sorry, forgot to say that I did replace the plugs and no difference. I think I'll send the carbs to Randy. Is that $40 per carb so $120 for all three? Do I have to drain out the fuel in them before sending?
08-14-2007, 08:57 AM #4
pm him on here, i believe his screen name is watcon. for 40 dollars a carb that is a smokin deal. yes, get all the gas out of those things before you put them in the mail.
08-14-2007, 12:12 PM #5
If it's only running 3800 rpm at WOT, then I bet it's not running on all 3 cylinders, or even 2. Hopefully that old fuel didn't cause you to burn down one or 2 cylinders. Do a compression check before you pull the carbs off. Don't run old fuel in these things...it's never worth it.
08-15-2007, 11:08 PM #6
Finally got around to checking compression and everything checks out great. ~120psi on all cyl. So I took the carbs off tonight and got in touch with Randy @ Watcon. They are off to WA for rebuild tomorrow.
Does anybody got a set of upper and lower carb gaskets they want to sell me?
08-15-2007, 11:53 PM #7
Twist Randy's arm for gaskets while he has your carbs.
08-17-2007, 09:34 PM #8
good call cleaning the carbs
Just wanted to say hi, I just bought a 96 sl900 2 weeks ago and have been looking at your posts (you have had the exact questions I have). I had to stay on the throttle too and it would start pretty shaky for the first couple starts. Do you find that it is unable to idle as well? Last night I took it out and BOOM I blew my front piston to smithereens and have an engine rebuild 2 weeks in...W-O-W. I am new to this stuff but so far so good, I am going to take picture and keep everybody posted, there seem to be quite a few of us with sl900s who are new to the sport on this forum. My ski actually rode awsome for the week I was on it, it could hit 60mph so I am a bit confused as to how the piston could have gone, it pretty much dissintegrated on top and one half is toast - I think that is due to a "lean condition" as I have read.
Good luck with the carb rebuild, I will be right behind you in line.
08-17-2007, 11:31 PM #9
Hey there Callan. Sometimes I feel like I am on an island with my SL900. Lots and lots of posts about the SL7** models, but I am cool with it cuz all the guys on this forum kick ass. They have helped me out so much and they reply literally minutes after I post. Can't say enough.
To answer your question, yes, will not idle AND I could only get the ski to about 5 MPH (not sure what that is in KPH being your Canadian, just kidding) at WOT. I hated running it this way because I was concerned about engine damage, but I had no choice. It wouldn't run at all if I didn't.
I do have a question for ph20, beer, zmann or anybody else out there...
When I was on shore, I could see the oil injection working awesome (at least I think). When I would look at the top of the carbs and squeeze the throttle while the engine was NOT running, I could see a very nice stream of what appeared to be oil from a brass looking fitting just inside the top part of the carb. Now when @ WOT and on the lake going 5 MPH, I am assuming the oil was entering the cyl through this fitting. Now here comes the question: If my carbs were plugged up and dirty giving a lean mixture due to the fact that very little of the air fuel mixture was actually fuel, does the oil actually cause the mixture to become more lean, rich, or have no effect on mixture? It seems to me that it would richen it up, but not sure and probably sound like a supernoob for asking.
Thanks in advance for that.
Callan, even though you had rough starts, after it started, where you able to hit speeds >5 MPH? Would it run normally @ WOT? Any performace degredation?
08-18-2007, 09:34 AM #10
Oil is not injected through those brass fittings...those are accelerator pump squirters...only fuel comes out of those, and the only shoot fuel when you squeeze the throttle. Oil is injected into the side of the carb, where it is mixed with fuel.
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