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To much oil, fouling plugs

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Water Crafts
95 xp and 99 gti
#1
99 gti 717. I've had a lot of issues with this ski but breakdown is compression good, carb settings good, spark is good, oil pump is set correctly, and no exhaust leaks. First off when I go to ride my ski the first thing I do is clear the cylinders to make sure there is no oil. Then I ride for 10_15 minutes and I lose MAG cylinder. Tow back and just about lost PTO as well with oil all over the plugs. Pull the plugs and no oil is in the cylinder or coming out. Really need help on this because I'm beyond frustrated. I read somewhere the banjos have check valves in them. Could this be my issue. Should I dare try oil block off? Any help will be appreciated.
 


mikidymac

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2003 GTI
2001 XP
1996 XP
1996 HX
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#2
If no oil is coming out or excessive smoke when starting then your carbs are really rich. Excessive fuel will foul the plugs, not just oil.
 
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Water Crafts
95 xp and 99 gti
#3
Fuel is ok. Carbs at spec. Yeas there is excessive smoke but it's not just on first fire up. It's all the time. Everyone says crank seal but I clear the cylinders before every ride after sitting for 2 weeks and nothing. If the crank seals were that bad wouldn't it blow out after sitting for that long? I've been told to try the loop system to the crank to see if I foul out the plugs.
 
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171
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Location
Grimsby Ontario
Water Crafts
96 XP 800 Limited Class
#4
Is your battery fully charged before or after your ride? (around 12.7 V )? Then I would do a load test on the battery. It would also be easy to check/eliminate the charging circuit (regulator, stator), from the equation/circuit.
 
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Water Crafts
95 xp and 99 gti
#5
Battery and spark are fine. Fouling plugs in 10 minutes then change plugs and 10 minutes later they are foul again. No oil when I clear cylinders before or after I ride.
 

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JeremyD615

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Location
Nashville, TN
Water Crafts
1995 Sea Doo Speedster
1995 Sea Doo XP
1996 Sea Doo XP
#6
Does the amount of time before the plugs foul change depending on how you’re riding? Does it seem to happen faster when it’s ridden hard or when it’s idling?
 

beergut

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Location
rindge, nh
Water Crafts
Too many to remember-
currently:
2011 RXT 260 iS
2018 Trixx 2-up
2005 Speedster 155
#7
compression test will only give you a partial indication of your cylinder health- a little oil making it past the rings while doing a compression test can actually seal the rings and give you a false impression. you really need to perform a leak-down test on each cylinder to determine if that's the case or not. We used to squirt a little oil in a leaky cylinder to rule out bad compression being caused by a ring or a valve; the oil will temporarily seal a leaky ring, but not a valve. oil can still be getting past the rings while the engine is running...
 
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56
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Water Crafts
95 xp and 99 gti
#8
Does the amount of time before the plugs foul change depending on how you’re riding? Does it seem to happen faster when it’s ridden hard or when it’s idling?
Yes it does seem to foul faster when riden harder
 
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Water Crafts
95 xp and 99 gti
#9
compression test will only give you a partial indication of your cylinder health- a little oil making it past the rings while doing a compression test can actually seal the rings and give you a false impression. you really need to perform a leak-down test on each cylinder to determine if that's the case or not. We used to squirt a little oil in a leaky cylinder to rule out bad compression being caused by a ring or a valve; the oil will temporarily seal a leaky ring, but not a valve. oil can still be getting past the rings while the engine is running...
I've only been into seadoo's for a year but catch on quick. Im guessing a leakdown test would mean filling the tops of the cylinders to see if it stays or leaks down?
 

beergut

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Premium Member
Messages
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21
Location
rindge, nh
Water Crafts
Too many to remember-
currently:
2011 RXT 260 iS
2018 Trixx 2-up
2005 Speedster 155
#10
I've only been into seadoo's for a year but catch on quick. Im guessing a leakdown test would mean filling the tops of the cylinders to see if it stays or leaks down?
pressurizing the cylinder with a few lbs of air with piston at TDC and watch if it holds for a period of time.
just youtube it. ;)
 

beergut

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Premium Member
Messages
161
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Location
rindge, nh
Water Crafts
Too many to remember-
currently:
2011 RXT 260 iS
2018 Trixx 2-up
2005 Speedster 155
#11
forgot to mention to the above... for 2 strokes, you need to make sure the piston is at TDC to seal off the cylinder ports, on 4 strokes you want to bring the cylinder to TDC on the compression stroke (both valves closed)
 

JeremyD615

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Location
Nashville, TN
Water Crafts
1995 Sea Doo Speedster
1995 Sea Doo XP
1996 Sea Doo XP
#13
Well the only places to get oil in the cylinder are the oil injection, the crank seals, or the RV shaft seal. I highly doubt it’s the oil injection system, as the only way to over oil with that system is to have the cable disconnected or the spring not under tension. Check the oil pump lever arm. If you move it with your hand, does it spring back?
 
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Water Crafts
95 xp and 99 gti
#14
I believe so but I'll double check. I know for sure its lined up correctly. As far as the rv shaft seal, do the symptoms match? I've never got oil out of the cylinders when clearing them before and after a ride.
 
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83
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10
Location
CO
Water Crafts
95 XP720 +3mm Bore
95 GTX657x +1mm Bore
#15
if you're not seeing any actual oil on the plugs or in cylinders it really sounds like way overly rich scenario.

However, if we follow the thought that it is fouling plugs from oil have you adjusted your oil pump as directed in the manual?

Did you rebuild the carbs? If so did you use genuine Mikuni parts to do so? Also, where are you located? depending on your altitude the factory settings for the carbs may not be correct. Living in Colorado if I set the carbs to factory setting its runs extremely rich and will flood well before I get out of the no-wake zone.
 
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56
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Water Crafts
95 xp and 99 gti
#16
I am seeing oil all over the plugs in 10 minutes of riding. Then I try clearing the cylinders before I ride and after I ride but nothing ever comes out. That's why I dont believe its crank seals.
 

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Messages
56
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2
Water Crafts
95 xp and 99 gti
#17
if you're not seeing any actual oil on the plugs or in cylinders it really sounds like way overly rich scenario.

However, if we follow the thought that it is fouling plugs from oil have you adjusted your oil pump as directed in the manual?

Did you rebuild the carbs? If so did you use genuine Mikuni parts to do so? Also, where are you located? depending on your altitude the factory settings for the carbs may not be correct. Living in Colorado if I set the carbs to factory setting its runs extremely rich and will flood well before I get out of the no-wake zone.
Yes carb was rebuilt with mikuni.
 

JeremyD615

Well-Known Member
Messages
1,086
Likes
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Location
Nashville, TN
Water Crafts
1995 Sea Doo Speedster
1995 Sea Doo XP
1996 Sea Doo XP
#18
I’m leaning toward it being a carb issue myself, and it flooding with fuel moreso than oil. The lever arm is quick and easy to check though, so do that first. If it’s okay, we will go through and verify that the popoff is correct and that the adjustment needles are in the correct place.
 
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Water Crafts
95 xp and 99 gti
#19
Sounds good. Soon as I can I'm gonna check those things and pull the carb to get a better look around the intake.
 

mikidymac

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Location
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Water Crafts
2003 GTI
2001 XP
1996 XP
1996 HX
1991 Superjet
2001 Superjet
#20
pressurizing the cylinder with a few lbs of air with piston at TDC and watch if it holds for a period of time.
just youtube it. ;)
This does not really apply to these 2-stroke skis. You have no oil control rings and have rather large ring gaps compared to a 4-stroke so a cylinder pressure leak down test really isn't that helpful. Also adding oil isn't really helpful either on these since there is plenty of residual 2-stroke oil on the rings anyways.

On these engines the best diagnosis for the pistons and cylinders is a simple compression test.

I will say a complete engine pressure test is a great test to determine leaking gaskets and seals to prevent lean conditions.
 

mikidymac

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Water Crafts
2003 GTI
2001 XP
1996 XP
1996 HX
1991 Superjet
2001 Superjet
#21
Sounds good. Soon as I can I'm gonna check those things and pull the carb to get a better look around the intake.
If your crank and rotary seals aren't leaking then it has to either be the oil pump pumping too much oil or too much fuel.

Does the ski start and run perfectly before it fouls plugs?
What is your compression?
 
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Water Crafts
95 xp and 99 gti
#22
If your crank and rotary seals aren't leaking then it has to either be the oil pump pumping too much oil or too much fuel.

Does the ski start and run perfectly before it fouls plugs?
What is your compression?
Absolutely compression is 148/150 runs hard and fast for a single carb 717. 47 mph on dummy gage. Carb has been rebuilt and sometimes I have to feather the throttle till she warms up so I really doubt its carb related. Smokes like a bitch and the plugs are wet and black. However crank seals dont seam to fit the symptoms.
 
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Water Crafts
95 xp and 99 gti
#23
I dont know for sure about the rotary valve leaking yet. Haven't had time to break it down yet.
 
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56
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Water Crafts
95 xp and 99 gti
#24
If your crank and rotary seals aren't leaking then it has to either be the oil pump pumping too much oil or too much fuel.

Does the ski start and run perfectly before it fouls plugs?
What is your compression?
Also if its pumping to much oil, is that the banjo check valves? What's the chances and odds they both went bad? My gut says rotary valve seal but I haven't heard of this happening very often if at all. Then again the owner before be was an idiot. I've fixed many of his mistakes. I went over everything including bolt checks. Didnt do the exhaust at the time because I didnt want to pull the pipe. Low and behold the bolts backed out and it came off. I originally thought that was the issue (recirculated carbon dioxide) but no it's still doing it. Also guess what spilled out of the exhaust that I noticed yesterday? A shit ton of oil.
 

mikidymac

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Messages
11,499
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Location
California
Water Crafts
2003 GTI
2001 XP
1996 XP
1996 HX
1991 Superjet
2001 Superjet
#25
If it is really black wet and nasty coming out of the exhaust that's typical of a leaking needle and seat.

The check valves would be suspect if it was flooding with oil when sitting.

Have you checked the oil pump adjustment?
 

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