1990 force 120 hp won't stay running. Need help!!

[Kylewoods]

I have a 1990 force 120 hp that was passed down to me. It has been sitting in a barn for 4-5 years. When I first got the boat it was in less than desirable condition (wires chewed, deck rotting ect.....)

Things I've done before turning the key:
1. Replaced impeller.
2. Drained and replaced lower unit oil.
3. Fixed all chewed wires and replaced as needed.
4. New batteries.
5. Replaced fuel lines.
6. Drained fuel tank.

After doing all the things I figured it was time to put it in a barrel of water and see what happened. To my surprise it started with a little coaxing it along. Fuel poured out of the top carb so I loosened the bowl nut, spun the bowl and tightened back down which fixed the issue. Took it out to the lake to do a test run and ran fine at first then started (what seems like to me) missing really hard. Got it back home and let it set for a couple of days then fired it back up in the barrel. Ran fine cold but when it came up to operating temperature started missing hard again. So hard it will kill the engine. Now it misses like that even on cold start.
Things I've done since then:
1. Checked spark on all plugs and found number 1 wasn't firing. Switched the coils around to see if it was a bad coil. Determined it was a bad cdi. Replaced with used cdi and now have spark on all 4. Issue still the same.
2. Pulled the fuel line that come from the pump to the carbs to test if fuel pump is pumping. To me it seems as though it is.
3. Checked the screen in the fuel pump and it was clean.

I'm at my wits end and not sure what to do other than take it to a mech. Could this be a fuel problem that I'm having? Could it be an ignition problem (such as stator or trigger or timing maybe)? Please help

 

[pnwboat]

Might want to replace the fuel pump diaphragm.

 

[Kylewoods]

Fuel pump is definitely the next thing i will try. Do you think that would cause it to miss like that? It's almost like it is backfiring, blowing water completely out of the barrel through the exhaust with a loud pop.

 

[tigfit]

Boy I have the same thing on a 1989 Force150!!!

 

[pnwboat]

You may also want to take the carburetor fuel bowls off and see if the is any crud in them as the result of sitting unused for so long. The other thing you should do is to check the compression. Good compression is important for a 2-stoke motor.

 

[Kylewoods]

Carb bowls are clean. Did compression test. It was 100 100 105 60.
Would that be a bad head gasket or bad piston?

 

[pnwboat]

Could be a bad head gasket or a problem with the rings on the cylinder that is reading 60lbs. Head gasket is pretty easy to replace, and not too expensive. They run around $40.

While the head is off, you can inspect the cylinders. Check for scoring or gouges in the cylinder walls. Sometimes the rings will get frozen into the ring grooves in the piston and won't seal properly causing low compression.

If you have a broken ring, it will also cause low compression and sometimes will put a gouge in the cylinder wall or take a chunk of the top ring groove with it.

 

[jerryjerry05]

They make a bore scope for the smart phones.
$20
Salt water?
​Take a look inside.
Remove the head.
​Be careful as the bolts can twist off fairly easy.