77 Johnson 140hp

[fmorlino2]

Hey guys what's up. I have a 77 Johnson 140 that I have a question about. It was sitting for who knows how many years. Rebuilt carbs, new fuel pump, plugs, impeller etc. Had it out on the river and ran 24 gallons through her no problems. It idled great came up to power great. Took it out a week later and she was good for an hour shut it off to fish. After that it would run for maybe 20 minutes ok then start dying and would not idle for ****. This would repeat. I noticed a cracked coil which I'm hoping is the problem. Compression is 140-150 all 4 cylinders. Anything else I should check? Thank you so much

 

[jimmbo]

You mention a Cracked Coil. Replace it, see if the Spark Jumps a 3/8" gap on every Plug Wire?
Might be a Fuel Tank venting issue.

 

[fmorlino2]

You mention a Cracked Coil. Replace it, see if the Spark Jumps a 3/8" gap on every Plug Wire?
Might be a Fuel Tank venting issue.

Yeah I'm going to replace all 4 coils. I have them on order. I had to put it away running bad and it's killing me lol l. going to get an adjustable gap tool and check for the spark. They look almost original to the engine and did not notice the crack before going out or else it would have been replaced so I hope the heat it just breaking them down from old age

 

[jimmbo]

It is 45 yrs old. 77 was the first year of the 140, and actually the best of them, it has the most finely Tuned Exhaust, the Crankcase Stuffers, and the Highest Compression Heads they used on the 140. Later years had slightly less compression(likely to enable it to survive on the Garbage marketed as Gasoline back then), the Stuffers were deleted, and the Exhaust didn't have the Tuner Megaphone in the Midsection.

 

[fmorlino2]

It is 45 yrs old. 77 was the first year of the 140, and actually the best of them, it has the most finely Tuned Exhaust, the Crankcase Stuffers, and the Highest Compression Heads they used on the 140. Later years had slightly less compression(likely to enable it to survive on the Garbage marketed as Gasoline back then), the Stuffers were deleted, and the Exhaust didn't have the Tuner Megaphone in the Midsection.

Good information to know. It's on my 78 crestliner that I'm refurbishing. If the hour meter is correct this engine only has 550 hours on it. Looking over the engine,other than aging electronics I would believe that hour meter. Was a lake boat from new York. I appreciate your input!

 

[jimmbo]

Which Crestliner? I had a 79 Crusader 550 open bow, I a 84 115 put on it. A couple of years earlier I had a 15ft Invader, which the Hull was a Flip of the fore mentioned Boat. Both boats were rated for 100hp, but I had the Dealer put a bit more on them.

 

[Faztbullet]

Rebuild fuel pump and recheck compression. This model ha the high ring pistons and are good for throwing off top ring.