1997 Gti runs only on 1 cylinder

[rjpiselli]

I have a 1997 Seadoo Gti with 717 engine. Ran fine all last yr, all this yr, up until last weekend it just stalled while riding. Wouldn’t restart.

Was close enough to the dock to swim it back, loaded on trailer and took it home. Will fire once but won’t start.

Took front plug out to check for spark, and with just the rear plug in the engine will run. With just the front plug in engine will not run, with both plugs in engine will not run. Swapped plugs and wire, engine will run with rear plug in on wire, but will not run with front plug in.

Any ideas what to do?

 

[Spider4real]

Check compression

 

[TheGTIjetguy]

Do you have spark in the front plug? I didn’t see the results in your post.
It makes sense that it doesn’t run until you remove the front plug. There is too much drag from the dead cylinder trying to make compression to allow it to fire.
Now you just have to figure out why it isn’t firing.