Force 120 runs on 2 cylinders

mikeb07087 · #1 (**permalink**) 07-08-2009, 08:28 AM

HELP!!!!
I have a 99 force 120 hp that I can't seem to get to run right.
It seems to only run on two cylinders-- usually the lower two
Idle is rough with a lot of sputtering

typically covering the upper carb has no effect on performance, covering the lower carb will result in a stall. removing the plug wires from lower two cylinders will run OK on the upper two cylinders, but still has rough idle.

Adjusting the carbs has no effect on idle speed or engine performance(other than stalling)

Timing is correct,
compression is good on all four cylinders
CDI packs check out per Clymer, and are all uniform
All four plugs are sparking
Carbs have been cleaned out about 5 times (just to be sure) New needles

new trigger coil (solved previous problems of runaway speed and kill switch not working-- scary!)
New stator--(old one was fine, clymer has the wrong specs for this unit)
(both stators (new and old) put out about 80 DVA volts to ground GW-gnd & WG-gnd)
new plugs
fuel recovery check valves are OK (2 replaced)

I am at my wits end-- got spark, got fuel, but not working right

boats.net · #2 (**permalink**) 07-10-2009, 04:58 PM

Sounds like carbs are not in sync or low speed jets are still plugged up in carbs.

mikeb07087 · #3 (**permalink**) 07-11-2009, 10:06 AM

The carbs are clean and in sync. ran gumout through all ports. At idle --sync is easy as both valves are closed. still in sync at WOT.

boats.net · #4 (**permalink**) 07-13-2009, 04:57 PM

What about reed valves, is it blowing gas back out through throat of carbs?