If your compression is good, a carb rebuild should do the trick
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93 GTS Crank No Start after fuel filter clean. Ran great before.
- Thread starter vert
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vert
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My compression seems to be OK - see pictures below. Carb has been rebuilt with genuine Mikuni parts just this summer. I actually took the carb apart again just now when I was refreshing the fuel system just to make sure there is no gunk in there. It was all clean.
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Yes the compression looks to be good, the picture is on a bit of an angle but looks like it’s around 132 ish, battery is good and strong? Rotary valve cover clearance? Maybe
Dang it!
vert
Member
So going back to the original problem - no start after fuel filter clean. I never water tested the ski after "fixing" the problem. In quotes because I don't know what I did, except from starting the ski on an aux gas bottle going directly to carb, then switching to regular gas tank fuel line. This made it start on the hose.
At that point I didn't test it in the water, only on the hose. After changing fuel lines/fuel selector/oil/oil filter/cleaning gas and oil tanks again it ran on the hose. At this point I tried water testing and experincing the current runs on a hose, not in the water problem.
So it's possible that my can't run in the water problem actually started after cleaning the fuel filter the first time. Not sure how I could mess that up, especially now with a new o-ring and filter screen. It's screwed on tight. Just trying to pin point the last thing that was changed before it ran perfectly fine in the water and it could be the fuel filter cleaning.
At that point I didn't test it in the water, only on the hose. After changing fuel lines/fuel selector/oil/oil filter/cleaning gas and oil tanks again it ran on the hose. At this point I tried water testing and experincing the current runs on a hose, not in the water problem.
So it's possible that my can't run in the water problem actually started after cleaning the fuel filter the first time. Not sure how I could mess that up, especially now with a new o-ring and filter screen. It's screwed on tight. Just trying to pin point the last thing that was changed before it ran perfectly fine in the water and it could be the fuel filter cleaning.
I know I’m probably repeating what’s already been said here, looked back briefly but didn’t read through the whole thread, maybe eliminate the possibility of it having any issue to do with fille filter or fuel selector valve by running a fuel line directly from the top of the baffle labelled ON to the carburetor
vert
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I was thinking of doing an aux fuel bottle directly to carb test on the water to eliminate all potential fuel supply issues first. If that actually works in water, then I've got a good starting point. Will also try putting a pair of older spare spark plugs and see if there's any change.
If there are other quick/easy tests I should try while I'm hogging the ramp please let me know!
If there are other quick/easy tests I should try while I'm hogging the ramp please let me know!
vert
Member
Additional testing done:
Any ideas on the next steps are appreciated. I'm determined to get this ski running correctly.
- Different set of spark plugs didn't make any difference
- Charging at 13.96v on the trailer while running - regardless of RPM. At most maybe a tenth of a volt difference (13.95-13.97). Seemed weird because I'm used to varying charging volts depending on RPMs on cars at least. Battery is at around 12.6v at rest. Is this normal?
- Took the ski to the ramp. Started right up out of the water.
- Down the ramp in the water no start. Disconnected the IN line from the carb (single carb model) and connected a small AUX fuel bottle directly to the carb. Started and ran a few minutes using up about 6-8oz of gas in the bottle.
- Connected the IN line back up i.e. back to stock set up. Started right up. Ran fine but wanted to be around 2100 rpms after messing around with the idle speed screw. At some point it started going up and down in rpms without any throttle input. From 2100 to 1500 or so.
- Started playing with the throttle and the video is below. Basically it idled fine around 2100, give it throttle and it bogs down and wants to stall, release - rpms go back up and will idle around 2100. Repeat several times until too much throttle stalls it out. Could not restart it in the water after it stalled out.
- Back up the ramp and out of the water it started right up.
- Home on a flush hose it started right up but the idle would bounce gradually from 3500 down to 2500 on its own.
Any ideas on the next steps are appreciated. I'm determined to get this ski running correctly.
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DougtheSlug
Member
I've run into a similar issue - starts ok out of the water but not when in. As burtshaver suggested on Friday, it's possible the rotary valve clearance is out of spec. How this could happen so suddenly is puzzling.... other than that, trying another carb is sometimes necessary. Even with a proper rebuild, there are cases where the carb is to blame.
DougtheSlug
Member
Another thought - it could be the coil is failing as happened to the other 93 GTS that is posted right above yours (won't rev up). It seems more likely for an electrical issue to occur when it's sudden like that (and the fuelling part is ruled out). I'm more familiar with snowmobile repairs & have sometimes used a timing light to see if the spark is failing under load.
Read through your thread again, just a few random thoughts, I read in your August 20th post that it was running good but was hard to start after sitting for 15 minutes, again maybe rotary valve clearance is out of spec. In your last post you hooked the fuel up directly from a bottle, it sounded to me like the machine was in the water and ran correctly on the aux fuel? Is that correct? Then back to running incorrectly once the fuel system was hooked back up correctly. If this is correct is it possible that the new selector valve you got off eBay for 15.00 is sucking air? This may also be a factor in the erratic rpm’s. If In fact it ran good off the fuel in the bottle then the valve of the filter is probably the issue, you can test them under 4 or 5 pounds of vac to test them.
Just looking at your last post and point #5 where you say the rpm’s went up to 2100 rpm’s after hooking fuel line back to stock set up. If it was idling fine at 1500 rpm in the water and 3000 or so out I would give it a minute before you do any adjusting of the idle, just my experience but I find after I have the fuel system apart I get higher rpm’s for 20 or 30 seconds due to the air in the line.
vert
Member
Another day another test. I did what you recommended earlier to rule out the fuel filter and the fuel selector valve. Connected the carb IN line directly to the reserve fuel pickup nipple, one of the 4 on top of the fuel tank. This test was done in the water on the trailer.
- Took a while to start even though I primed the line - maybe 30 seconds of cranking total.
- Once it started I had to adjust the idle and then it idled for a long time without issues.
- Giving it gas the ski would not rev past 3500 rpms. If I kept the gas lever pulled all the way to try to get to higher rpms, the engine would eventually want to stall out. If I released the gas lever in time before stalling the ski would go back to idle and stay there just fine.
- After stalling out the engine I was able to restart it in the water and idle as long as I wanted.
I can get into the rotary valve clearance but wanted to do these simpler tests first. Not sure I'm getting anywhere though...
Yes, although a few things are pointing to the rotary valve clearance being out of spec I do think there are other issues going on here. Couple of things come to mind but I’m not sure in any of them, someone else had mentioned in a previous post that sometimes even after a rebuild the carb can be the issue, I would be looking at the carb again now, the filter and valve are currently ruled out after running a direct line. Where did you purchase your carb rebuild kit? When you were cleanjng the carb, did you see a good flow coming from the small holes in the carb throat? And now I’m going to jump in a different direction, again I’m definitely very far from knowing what I’m doing but I’ve read multiple times that the regulator/rectifier can cause all sorts of problems, I tested mine once by unplugging the red wire on my 97 GSX.
vert
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Thank you for recommendations. I do appreciate any and all the help.
I bought a genuine Mikuni carb kit. The original parts looked mostly fine but I replaced it all following video DIYs. That was in the spring and it ran great several times I was out this summer until I changed that fuel filter. Since then I've had the carb off two more times and it was always clean. Yes, good flow through all the holes, cleaned with carb cleaner and air.
Is there a way to test the regulator/rectifier on this 587 motor?
vert
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So to test the rectifier I found this recommendation:
Rev your engine to about 5500rpm. If VDC is below 13 or above 15 VDC, then High probability you hv a faulty rectifier.
Based on my yesterday's test mine is at around 13.96v no matter what the rpms are. So sounds like the rectifier is good then?
Yes that is correct. I have read that multiple times. When I was having issues above 4500 rpm I was told to remove the red wire from the rectifier (that was last fall so memory isn’t the best) if the issues went away then rectifier is bad. But I’ve also seen the test you mentioned. I don’t think I will be of any help to you, just don’t know where to go from here, I’m browsing through the 93 manuals electrical section now, if I see anything I think might help I will let you know. Hope you can get this figured out
vert
Member
Rectifier test results:
- Disconnected the red wire on the rectifier.
- On trailer in water - similar behavior as before. Idled fine. Wouldn't go past 3000-3500 rpms. Stalled out at full throttle.
- Couldn't restart after stalling in water.
- Pulled the ski out of the water and it started. Idled fine, would start trying to stall on throttle but then would rev up.
- Put it back in the water, started fine and acted same as #1.
- Connected the red wire.
- Running at home on a hose the voltage was around 13.3-13.5 depending on the rpms. RPM/Voltage picture below.
Grim
Well-Known Member
Do you remember what your pop off was, and you did a leak check as well?
Funny, I was just reading through the thread to see if I could find his pop off numbers. I’m definitely thinking something is not right with the carburetors and this is more of a question would weak spark cause this condition of starting out of the water but not in the water? I think at some point the rotary valve clearance should be checked and/or maybe a compression test taken with a different tester. I think it’s possible we may have more than 1 issue to deal with here
vert
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Unfortunately I didn't do these tests. I don't have the right tools for this.
Will post compression test results soon. Just got a new tester. Previous tests showed 135 psi on both cylinders, done with a loaner tool from Autozone.
I wouldn’t be to concerned with getting a different compression tester, the reason I had suggested it was because if it starting on the trailer but having difficulty in the water, I mean it is is possible that the tester wasn’t accurate but at this point I would be leaning more towards needle and seat either leaking or incorrect spring ( pop off ) The tools for the pop off test can be made for around 30.00, just need a T fitting, gauge for on top of T fitting, schrader valve for one end of T and a barbed fitting in other end of T. I would get a gauge from 0 to 100 as some of the carburetors pop off as high as 56 pounds
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