95 Superjet wont accelerate

B

bobm

Location
ny
I have a 95 superjet. I took it out recently and when I give it full throttle it doesn't go more than 5-10 mph, backfires, and stalls out. I tried adjusting the high and low speed on the carb but it doesnt seem to help. I thought I had an exhaust leak because the exhaust manifold gasket was pretty beat up. I replaced the exhaust manifold gasket but that didn't fix the problem. Any suggestions on how to troubleshoot? Should I check for an air leak? Would that cause this problem? Any suggestions are appreciated.
 
SuperJet-Dave

SuperJet-Dave

Location
Rochester, NY
bobm said:
I have a 95 superjet. I took it out recently and when I give it full throttle it doesn't go more than 5-10 mph, backfires, and stalls out. I tried adjusting the high and low speed on the carb but it doesnt seem to help. I thought I had an exhaust leak because the exhaust manifold gasket was pretty beat up. I replaced the exhaust manifold gasket but that didn't fix the problem. Any suggestions on how to troubleshoot? Should I check for an air leak? Would that cause this problem? Any suggestions are appreciated.
Click to expand...

Could be a number of things. Simple things to try first are fuel filter (try bypassing it), same with res/on fuel switch, replace fuel, new spark plugs, new fuel lines, rebuild and clean carb,....
To test further for an exhaust leak, see if it does the same thing with the hood removed. If so, likely no exhaust leak.
 
B

bobm

Location
ny
Thank you for the info.

I have replaced the plugs, fuel lines, rebuilt the carb, and disconnected the res/on fuel switch. Also checked the one way valve on the gas tank. I will check the fuel filter and try replacing the gas next.

I tested with the hood off on the water last week and it still did the same thing.

I will let you know if the gas or fuel filter help.

I appreciate the suggestions
 
B

bobm

Location
ny
fuel filter and gas are good.

ski seems to run fine out of the water when hooked to the hose. As soon as I put it in the water it runs horrible. I am going to do a leak down test next. After that I will check the reeds. After that I will pull the flywheel and check key and stator.

Any other suggestions?
 
SuperJet-Dave

SuperJet-Dave

Location
Rochester, NY
bobm said:
fuel filter and gas are good.

ski seems to run fine out of the water when hooked to the hose. As soon as I put it in the water it runs horrible. I am going to do a leak down test next. After that I will check the reeds. After that I will pull the flywheel and check key and stator.

Any other suggestions?
Click to expand...

Yah, fuel filter or fuel would have been way too easy. These skis can be a pain sometimes. Have you done a compression test on the cylinders?, and do they check out ok (150+ psi within 5 psi of each other)?
So the problem only happens under a load... could the driveshaft be slipping? Impeller loose? You would probably hear these though....

Checking for leaks and reeds makes sense as next steps
 
B

bobm

Location
ny
I pulled carb from another ski 2 weeks ago to troubleshoot a different issue. Took ski out for a few hours and it ran fine. I took the Ebox apart to resolve a problem with the start/stop switch. The start/stop switch is working but now it won’t accelerate.

Compression is 120 psi in both cylinders. Driveshaft is not slipping and impeller is not loose.

Thx
 
Big Kahuna

Big Kahuna

Administrator
Location
Tuscaloosa, AL
SuperJet-Dave said:
Yah, fuel filter or fuel would have been way too easy. These skis can be a pain sometimes. Have you done a compression test on the cylinders?, and do they check out ok (150+ psi within 5 psi of each other)?
So the problem only happens under a load... could the driveshaft be slipping? Impeller loose? You would probably hear these though....

Checking for leaks and reeds makes sense as next steps
Click to expand...
It has been back firing. Not a driveshaft issue.
 
SuperJet-Dave

SuperJet-Dave

Location
Rochester, NY
bobm said:
I pulled carb from another ski 2 weeks ago to troubleshoot a different issue. Took ski out for a few hours and it ran fine. I took the Ebox apart to resolve a problem with the start/stop switch. The start/stop switch is working but now it won’t accelerate.

Compression is 120 psi in both cylinders. Driveshaft is not slipping and impeller is not loose.

Thx
Click to expand...

I guess you could recheck all the connections and grounds in the ebox. Wires can get pinched reassembling the ebox as well. If you have another superjet around with the same CDI part number, you could try swapping that in. I am not certain if a faulty CDI could cause your particular issue, but would not be surprised.
Too bad you cannot repeat the issue out of the water.

120 psi would seem to be problematic.
 
B

bobm

Location
ny
I pulled the Ebox again to check all connections and looks good. I did an air leak test and checked the reeds. Both of those were good. I will check woodruff key and stator next.

Thx for all the suggestions.
 
B

bobm

Location
ny
Finally found the problem. Pulled flywheel and stator screws were loose so timing was off. Tightened everything up, took it out, and it ran good.

Thanks for all the suggestions
 
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