1990 Force 90HP ---stumbles/jerks/dunno?

[hotride454]

I got a sweet deal on this 1990 bayliner 18ft ski boat with a 90 hp force.....or at least i thought so So I tried to start the boat, but it had been sitting for a while so the carbs were all gooey. Took 'em apart and cleaned them thoroughly, put them back on and it started, but ran roughly. it would jerk/miss out every few seconds, and will not idle. it will run WOT, but if you back off the throttle, it dies. definately backfiring out the exhaust. Compression all checks out around 100-105 psi. Have removed, cleaned, and installed carbs like 4 times...new fuel line and primer bulb, the fuel pump diaphragm looks perfect...the spark plug ends were cheap and rusty so i replaced them...I"M SO LOST PLEASE HELP ME ENJOY THE LAKE THIS SUMMER!!! thanks

 

[12Footer]

Re: 1990 Force 90HP ---stumbles/jerks/dunno?

Welcome to iboats, Hotride. Those compression numbers are pretty low. They should be 135-155PSI, accordin to the "Force book of knowledge".<br />Compression that low could interfere with proper fuel pump operation. Before tearing it down, I would run some decarb cleaner thru it, and recheck the compression. If it improves, that was the problem.<br />By cheap and rusty, I hope you were refering to the outside of the plug. Any rust on the anode,or threads, and you may have a bad head gascket or warped exaust port plate, causing water to get inside the combustion chamber.<br />.