1991 SJ650 superjet

D

DamonT

Location
Nine Mile Falls Wa
1991 sj650
replaced the stater last winter, rebuilt carburetor and changed the fuel filter. starts great, idols just fine, when I try to increase the throttle the engine will try to cut out like it’s not getting enough gas. Swapped the carburetor out with the same type of JetSki to try to narrow down the problem and it had the same problem. Which illuminates the carburetor. Can a stater be the cause of this kind of problem?
please help
 
T

te4250

Location
Western NY
Unfortunately it seems with these motors this symptom can point to almost any problem, stator could be the issue, cdi, could just need plugs. Could also be a fuel issue external to the carb. Motor could even have low compression and run like that, although ime 650s seem to be indestructible. I’d swap plugs first cause they’re cheapest easiest and could probably use replacing anyway, visually inspecting as well as testing resistance on the stator also won’t take long and could be revealing, cdi easiest way to test is swap in a known working unit.
 
brapperdoodle

brapperdoodle

Location
Asheville, NC
I always like to mention that the fuel system must be able to hold pressure and needs to have a proper breather attached. If you have even a slight pressure leak in a line or at the fuel cap, it could give you problems. If the lines are old and hard, replace them. OEM lines are really nice and usually don't have issues...
 
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D

DamonT

Location
Nine Mile Falls Wa
Thanks for the suggestions. Over the winter did standard maintenance; fuel filter, plugs, crb rebuild, tank check valve. Only major component change was the stator; which died at the end of last summer. Tank holds pressure, compression is good. I’ll be slaving in suspect parts from identical superjet to find the culprit. Unfortunately I can’t duplicate problem on the stand, have to take it to the lake for every trial run, which will take time. I’ll post the fix when I find it. Still open to suggestions, any help is appreciated brothers.
 
mthomps

mthomps

Location
Cleveland
Dont give up.. Start over and focus on electronics. Buy a new oem cdi or hit up @JetManiac for assurance it is a known good one.

An effed cdi can and will confuse the hell out of you

I once bought an ebay cdi for 50 bucks to replace a cdi that would make it backfire. 2 rides later it would crank all day long and never start.
 
brapperdoodle

brapperdoodle

Location
Asheville, NC
1 last thing to mention, I had a very similar problem on a 440. The ski was so clean and ran great (out of the water) but wouldn't run for chit in the water and would constantly die. I decided to rebuild that engine and before I disassembled it, I pressure tested it. Before I got to 5 psi the front crank seal blew out. (I had the flywheel removed) Literally blew the lip out. SO, could be an air leak too? Just don't want to exclude any ideas!
 
fx1mark

fx1mark

Location
Alabama
I had a mysterious problem with my fx-1 once. It turned out to be my new SBT coil. picked up a used oem coil and fixed the problem.

Edit: I got to thinking about this and it was a WSM coil, my bad.
 
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