Ski runs fine on trailer but not in water.

S

shank

Location
australia
The ski runs fine through all rev ranges on the trailer dry. As soon as i put it in water it wont start easily and it runs like a dog and only low range revs and throttle pretty much stalls it.

So i have done the following
- Checked for exhaust leaks. Could not find any
- Pulled carbs fully cleaned them and put back together - no difference
- pumping fuel while running in water with a primer. no difference
- Checked if related to hood on or off (was thinking air problem). - no diff
- Pulled motor and found stator chamber dirty with some water. cleaned flywheel. stator, bendix. so they much beter. Checked resistance on crank sensor and it ok. Checked regulator was still charging and magneto good (later when motor back in ski) all good. Runs fine on trailer again. Not in water
- Pull ebox out. Clean as a whistle. Have not seen one this clean in a ski this age before.
- checked resistance on coil spark leads. all ok.
- dont know of a way to test CDI.
- battery measuring 12.4 volts. CCA must be fine as engine is cranking. dont have CCA tester

Any ideas ?
 
john zigler

john zigler

Vendor Account
Location
wisconsin
I am wondering if you have a bad water box baffle? Being in the water would affect this.

What is your compression?

A ski will typically run much better out of the water as there is no load on the engine. You have to have a good ear to hear if it is running maybe on one cylinder (Common) or if the rev limiter is kicking in early (Also very common).
 
S

shank

Location
australia
I checked reeds when i pulled carbs. Also thought this symptom would occur on trailor with broken reed. Also thought back fires would occur.

It running on two cylinders on trailer. I mentioned i ran it with hood off in water
and it didnt sound like a miss fire on one cylinder to me.

Havnt checked compression would have to borrow a guage. Doubted this would b a problen as ski was working in water about 5 days before symton occured. I will check it when i can.

If revs where being limited then why would it stall though is my question on that.
 
MarkWalker

MarkWalker

Site Supporter
Location
Buffalo NY
Years ago, a friends Superjet had all of these same symptoms. It ran great on the trailer. In the water, nothing. After swapping parts in and out for months. It ended up being a bad crank bearing.
 
Jhucke

Jhucke

Location
Wisconsin
MarkWalker said:
Years ago, a friends Superjet had all of these same symptoms. It ran great on the trailer. In the water, nothing. After swapping parts in and out for months. It ended up being a bad crank bearing.
Click to expand...

I was going to say something similar. Years ago my first superjet purchase, started instantly and ran well out of water. Naive me, no compression check and handed over money. Took it to the water and didn't run at all. Lo and behold, 30 psi front cylinder, rings were purely detonated and welded onto piston head. Luckily the seller agreed to give me some money back (he didnt have to).
 
SuperJet-Dave

SuperJet-Dave

Location
Rochester, NY
shank said:
The ski runs fine through all rev ranges on the trailer dry. As soon as i put it in water it wont start easily and it runs like a dog and only low range revs and throttle pretty much stalls it.

So i have done the following
- Checked for exhaust leaks. Could not find any
- Pulled carbs fully cleaned them and put back together - no difference
- pumping fuel while running in water with a primer. no difference
- Checked if related to hood on or off (was thinking air problem). - no diff
- Pulled motor and found stator chamber dirty with some water. cleaned flywheel. stator, bendix. so they much beter. Checked resistance on crank sensor and it ok. Checked regulator was still charging and magneto good (later when motor back in ski) all good. Runs fine on trailer again. Not in water
- Pull ebox out. Clean as a whistle. Have not seen one this clean in a ski this age before.
- checked resistance on coil spark leads. all ok.
- dont know of a way to test CDI.
- battery measuring 12.4 volts. CCA must be fine as engine is cranking. dont have CCA tester

Any ideas ?
Click to expand...

This may sound like an ignorant suggestion, but it solved a similar problem I had a few years back.. after much effort swapping parts. It ended up being a bad fuel filter. For some reason it passed fuel without a load, but once in the water it would only barely run in the low end and would stall at the high end. It is simple to try, just remove the inline fuel filter(s) and see if it runs better in the water. This is unlikely, but worth a shot before taking on some more invasive work.
Good luck!
 
S

shank

Location
australia
i found the problem got a compression tester. Drive shaft end cylinder. 30 PSI. Front cylinder 150 PSI. So with load on water in virtually on 1 cylinder of power.

Only issue is i have not found the reason for the compression being wrong yet. I have only pulled the head and not the cylinders so far.

- i poured a bit of oil down cylinder and checked compression it went up to 40 PSI not much diff. The oil i believe helps detect ring probs
- I checked head gasket for any blown out marks but nothing looks wrong with it at all.
- i put head back on with same gasket. torqued and got same compression.
- i checked head for warping with a straight edge and finger gauges. Specs say i can have up to 0.005 mm gap and i couldnt finder any with guage.
- i checked with finger guage ring gap in cylinder and it appeared to be ok.

I am thinking going to have to pull cylinders and visually inspect rings as i dunno what else it could be at the moment.

The top of the cylinder with 30 PSI does not look normal. looks like detonation maybe.

I have attached pics.

I am thinking pull the cylinders next. Someone mentioned they had blown rings causing this issue. Also mentioned crank bearings which i could check with cylinders pulled

Whatyas reckon ?
 

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S

shank

Location
australia
Also several of the head bolt studs snapped. I pulled all the studs as they not all in good condition. Had to heat most of them to get em to move. Can i just buy stainless bolts to use as head bolts. I tried some hex head ones but they squeaked as i torqued them so i stopped. The head dome nuts on studs dont squeek.
 
fastgtfairlane

fastgtfairlane

Location
Charlotte, NC
Hard to tell from pics but the last pic looks like a piston seizure on the rear cylinder next to the exhaust port. I can see what looks to be aluminum from the piston. Probably stuck the ring. If you decide to get the cylinder bored, I'd send the old pistons. The machinist will be able to diagnose the cause of the seizure. Wouldn't be a bad idea to do a proper leakdown to make sure you don't have an air leak causing a lean condition
 
Quinc

Quinc

Buy a Superjet
Location
California
SuperJet-Dave said:
It ended up being a bad fuel filter.
Click to expand...

I had an issue with fuel filters as well! Spent a whole season trying to track down an air leak, pulled the engine multiple times and pressure tested it etc. Ended up being both fuel filters where sucking in air through the plastic.. Figured it out when pulling the engine and blowing the gas in the lines back into the tank and bubbles came out of the filters..
 
john zigler

john zigler

Vendor Account
Location
wisconsin
You are running lean. (Piston wash) you have detonation for sure on the rear cly, scoring, and aluminum transfer to the cyl from piston. Time to go through your engine completely.

Make sure you look over your crank very carefully.

We offer complete machine shop services if you need. I have rebuild kits, crank seals, case sealer, and can bore your cyls is you want.
 
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