1977 140 HP Johnson Question

[RR24]

I was checking things out tonight, to get the boat ready to go for this weekend, and notcied when i pulled the spark plug wires off one at a time, that on number 1 the engine only dropped about half as many RPM's (by the sound of it) as the others. Could this be a weak coil? Spark plugs looked good, only have about 8 hours run time on them from last year.

Any ideas would be great, thanks Wes

 

[Daviet]

Re: 1977 140 HP Johnson Question

You might check compression, maybe squirt some fuel into the carb and see if it picks up.

 

[RR24]

Re: 1977 140 HP Johnson Question

compression on all 4 around 100 to 110, also carbs just rebuilt


Wes

 

[emdsapmgr]

Re: 1977 140 HP Johnson Question

The normal compression on taht powerhead when new was in the 130 range. That was a very high compression engine at the time it came out. It will run with your current compression numbers, but will be down on hp somewhat. You may want to do a decarb on the powerhead to see if the compression will come up. See your Bombardier dealer for a product called: Engine Tuner. Follow the directions on the can. A second application won't hurt.

 

[RR24]

Re: 1977 140 HP Johnson Question

not the coil, will try squirting fuel next to see what happens, decarb was done last year maybe needs again I guess