Misfire Cylinder 2000 Wellcraft Fish 180 CC

[ShawnThomas1978]

2000 Johnson 115 2-stroke. I bought the boat, they said the boat sat for a year, they pumped 10 gallons of bad gas out of it. Now the boat is misfiring over 5000 RPM's. The boat idle's fine. When crank on it, it sounds bad. Sometimes it won't, and will get up and plane fine, run 40 mph. Than boom, all a sudden it starts misfiring. Plugs changed, fuel filter. Any suggestions what the problem could be?

 

[cr2k]

Re: Misfire Cylinder 2000 Wellcraft Fish 180 CC

Could be lots of things. loose wires, weak fuel pump.

I would start by checking wire connections under the hood. You can idle on muffs and start wiggling wires to see if you can duplicate. Do Not run at high RPMs without a load on engine.

Easiest way to diagnose would be to take to shop with dyno so they can run WOT and start wiggling things. Like trigger wires that may be worn through and shorting out at just right conditions.

 

[ShawnThomas1978]

Re: Misfire Cylinder 2000 Wellcraft Fish 180 CC

Dyno with WOT... And that is ?

 

[jonesg]

Re: Misfire Cylinder 2000 Wellcraft Fish 180 CC

dyno WOT,
On a dynomometer at Wide Open Throttle ( in a test tank).

Don't do that unless you draw a complete blank.($$)

The best way is to do a complete engine check.
Buy the factory service book ( not clymer/seloc) from dealer.

Compression test. Write numbers down.
Go to autozone and buy a spark gap tester, it must be adjustable.
Set gap to 3/8th inch, remove all plugs and check ea cyl for spark.

Do it cold, if its good then run it up to temp on the hose at high idle and do it again, a coil could be dropping spark when up to operating temps.
You can use a timing light to find a dead cyl too.
Check coils for cracks, watch for stray ignition spark from wires.
Inspect sparkplugs for any that appear different, might be wet or oiled up.

If all passes good then rebuild the carbs with new kits.
I'd personally do all of that regardless.

 

[ShawnThomas1978]

Re: Misfire Cylinder 2000 Wellcraft Fish 180 CC

Istalled a water/oil seperator and it seems to have fixed the problem! Seemed like water was in the gas. Drove like butter today. Going to re-test drive it tomorrow. Keeping my fingers crossed!