Bottom cylinder won’t fire but still has spark

[Caden Schaack]

im not sure what’s going on but I’ve thought many things were wrong with my 1995 Johnson 120 but what I have finally found is that one cylinder won’t fire but it does get spark. You can take the plug wire off while running and it won’t change. We cleaned the carb that is in line with the cylinder but that didn’t fix it.

 

[dwco5051]

Do a compression check on all cylinders first and give us the numbers.

 

[Caden Schaack]

They are all between 120 and 130

 

[Caden Schaack]

One side they are both 121, other is 130 and the one that won’t fire is 125

 

[flyingscott]

I believe that is an xblock looper. That means the portside cylinders use the starboard carbs and vice versa. I believe, if not somebody will be along to contradict me.

 

[racerone]

Agreed ----Look at the other lower carburetor.----These cross over.----Looking from front of boat the bottom right carburetor feeds the bottom left cylinder.

 

[Caden Schaack]

Alright I will dig into the other carb and see

 

[Caden Schaack]

Alright I cleaned the other carb now when it is running I pull the plug and it hesitates the slightest bit so I’m hoping that fixed it. It still pops once warmed up but I’m hoping that’s just because it’s not getting back pressure from being in the water.

 

[racerone]

Make sure carburetors are free of restrictions.----No fuel going in also means no oil ??----Compression test results are ???

 

[Caden Schaack]

At one point a put in a little bit of wd40 for that fact, I listed the compression in an earlier reply

 

[racerone]

If a carburetor is plugged then one cylinder will be starved of oil.----Little bit of WD 40 won't help at all.

 

[Caden Schaack]

I’m hoping it’s good now I don’t think anything in the cylinder got damaged, spark plug in that cylinder also looks good too