1984 90 hp Johnson Missing 2 cylinders

[Boat84]

Hi everyone,
This is my first time on this forum. I purchased a 1984 Procraft that has a 90 hp Johnson. This boat has been sitting up for 3 years. I've got it running but it's missing on the 2 Bottom cylinders. I've checked the Compression and it's 125lbs on all 4 cylinders. It's also firing on all 4 cylinders. I had to clean out the carbs when i got it cause they were gunked up. I Took the Self Mixer off and now mixing it myself 50:1. I've Took the Boat out on the water and seems to idle and crank fine. After warming up, I'll give it full throttle and it will take it for a second then bog (Never runs at full throttle). I can bring the throttle back down and it will run better. So far it hasn't run good enough to plain out. I've checked the bottom 2 cylinder while it was running and it doesn't change the motors idling conditions at all when the spark plug wires are removed. Removing the top 2 plug wires changes the motor idling speed Greatly. Seeing how the compression is good and I have spark on the bottom 2 cylinders made me think it's not getting GAS. Took the Bottom 2 spark plugs out and turned the motor over and can see the Mist of Gas coming out Leaving me PUZZLED. Anyone have any idea on this problem?

 

[tashasdaddy]

Re: 1984 90 hp Johnson Missing 2 cylinders

what do the plugs look like?

 

[CharlieB]

Re: 1984 90 hp Johnson Missing 2 cylinders

Compression

Spark (near the right time)

Fuel (near the right mixture)

Your compression is enough, spark timing is fixed by the triggers shared with the top cylinders so timing isn't the issue.

Botom carb must not be mixing fuel near the right amount yet.

First thing would be to look down the carb throat while pumping the primer bulb to see if any fuel flow/flooding is occurring.

 

[mikesea]

Re: 1984 90 hp Johnson Missing 2 cylinders

Your bottom carb is likely dirty.To do a good carb cleaning,you need to totlly take it apart and soak in a carb cleaner solution,OMC engine tuner throughly sprayed on all theparts often helps.Problem is in the internal passages of which you cant see.You cant simply spray a carb cleaner on the parts.Remove all the jets including the high speed ones,which are probably the suspect in this case,they are located in the bottom half of the carb behind the brass screws ,they have a slotted head and need a good screw driver with a thicker than normal slot for that size driver to remove or you will strip the slot.,OMC of course makes a SPECIAL tool for removing

 

[Boat84]

Re: 1984 90 hp Johnson Missing 2 cylinders

The Plugs look Wet with gas, like it's not burning it