300/440/550 550 wont stay running

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dezzerts10

Location
riverside, ca
i got a 87 js550 that wont run. it ran fine last season and when to take it out this weekend and cant keep it running. it will start with the primer and rev if you give it throtle but dies right away. if you try to keep it running with the primer it bogs and backfires through the carb. i did a carb rebild kit and it made no differance. i also read about the flywheel key stripping so i checked that and it was fine. anyone have any ideas what mite be wrong?
 
L

Laserman

World's Fastest TYPHOON
Location
Orlando, FL
Here's some things to check:

Old gas?

Split pick-up tubes in gas tank.

Clogged ON\RES switch.

Leak\crack in fuel lines.

Pulse line cracked.

plugged exhaust.
 
D

dezzerts10

Location
riverside, ca
i did a compression check, has 100 in both holes. in the beggining i was workin on it at night and could see flames in the clear pulse line. i took the line off and it did have a hole in it so i replaced the line, but no change. i drained all the fuel out at the end of last season and just puy in fresh gas. i checked the whole fule system, seems fine. i even disconected the return line and it flows pretty good when it runs... im thinking it a timming problem but if the flywheel and stator are fine what else could it be?
 
D

dezzerts10

Location
riverside, ca
b.lee said:
Route the fuel line from the gas tank directly into the carb.
(by passing the fuel on/off switch)

See if this helps.
Click to expand...

ok i just did this and it did help. i can start it with the primer and keep it running as long as i keep the rpms up. but as soon as i let the motor slow down it starts to die and if i give it some gas it bogs and spits fuel out the top of the carb then dies. the only thing i didnt repace in the carb was the needle and seat and i dont have the tool to check pop off pressure. could it be one of those?

thanks for all the help so far!
 
b.lee

b.lee

Team Cheeseburger
Location
Lapeer County, MI
100 psi it pretty low compression.
Might not be your issue though... if you plan on keeping the ski I'd get the top end rebuilt. (bore/hore/pistons)
 
jetski9010

jetski9010

Team RTYD
Location
Lancaster PA
Will it idle now or just die? If it dies at idle take your fuel return line off while its idleing and see if its spitting fuel out. If so you at least know its pumping fuel to your carb. 100 psi compression is under the service limit but it should still run will just be a lot harder to start and have weak performance. If your planning on keeping the ski I would get the engine rebuilt with a fresh top end and new crank seals and go from there.
 
slipmag

slipmag

Freak Motorsports
Location
New Iberia/Avery island, La
i vote for top end.... had the same problem in mine...pulled it apart and measured the ring end gap...mine was way too large, cylinders were worn...bored with new pistons and shaved the head....

its all good to go.

hope this helps.
 
S

standupjetskirider

Location
upstate ny
did you ever figure out what it was cuz mines doing the same thing... the things i did to try fixing it was changed the spark plugs and cut back wiries then i looked into timing took off the stator cover and noticed oil so i changed the crank seals and why i was in there did a top end and put two new coils on cuz of the oil in the cover and thought my pulser coil was bad.. no change so i rebuilt the carb and still no change... so i took the e box ( the complete box) out of a running ski and no change... im so stumped and dont even know where to start again...... please help if you think you can...
 
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