1977 85hp Johnson not running up to par

[bukeyeocean]

Hello all,<br /><br />I am having a problem with my Johnson not running well. I will give some back story so it helps. Last year at the end of the season my boat was tampered with and sunk. I pulled the boat took it back to the garage and did what I could do as far as getting all of the water out and what not. After I was done I took it to the local Johnson dealer/mechanic and they had it for a week and cleaned all up. He told me everything ran fine and it seemed to. It was stored for the winter. I just got around to getting it back out in the water. Now here is the problem.<br /><br />I did the regular maintence on it and ran it for a few with a water hook up. Everything seemed great. I launched it and took off. The boat planed and was going better than normal for about 10 minutes. Then the boat just slacked off on power. The best way to describe it is running at half power, but at full throtle. I shut it down and set there idling for a few minutes and everythign seemed normal again. When I took off again it was normal power until right before plane then it went to the half power. I turned the boat around and pulled it. When I got home I checked the throtle control and the drivers set and everything looked to working fine. I have not got a chance to look at anything else because of work. I will be messing with it this weekend and would like some help where to start. So please help me with this. I really like the motor and the boat is not worth buying a new one.<br /><br />Thanks,<br />Charley

 

[mjash]

Re: 1977 85hp Johnson not running up to par

Had the same problem last week with mine ...Ran about 3000RPM @ WOT. I came to find out that 2 of the cylinders were not firing. A few things you could check. <br /><br />1 Look at all plugs...See if they are wet or dry.<br /><br />2 Do a compression check on all 4<br /><br />3 Check for spark on all 4 plug leads.<br /><br />For me the port side cylinders were wet with fuel when I removed them and there was fuel coming out the exhaust. The boat was running about 700 RPM on muffs and would stall at idle. Checked compression 110-115 on all 4. I checked all my wiring...looked decent....Checked for Spark @ spark plug leads. Nice strong spark. Today I changed all 4 plugs and voila...Fired right up to about 1050 rpms and no stalling. Until you narrow it down a bit I am just guessing. Als there is a post on how to check the coil sensors. Unhook Terminals 2&4 and 9&12. With an ohmmeter check accross leads that went to 2&4 and then 9&12 both readings should be about 8 ohms.

 

[R.Johnson]

Re: 1977 85hp Johnson not running up to par

How long was the engine sunk? In what kind of water, river, lake, ocean? How long before it was looked at after being sunk?

 

[bukeyeocean]

Re: 1977 85hp Johnson not running up to par

Mark A64:<br />Thanks for the help that is what I was planning on doing. I didn't know if there was any other secret that I may of over looked.<br /><br />R.Johnson<br /><br /> How long was the engine sunk? Less than 24 hours.<br /><br /> In what kind of water, river, lake, ocean? Man made fresh water with muddy bottom. Average depth of 8'-10'.<br /><br /> How long before it was looked at after being sunk? I looked at it with in an hour of pulling it. The dealer looked at it within 48 hours of pulling it.

 

[ob15]

Re: 1977 85hp Johnson not running up to par

I wonder what the dealer did. He may have just fired it up & that's all. If he just fired it up, I would look for bad and/or corroded wiring and rebuild the carbs. What about fuel? Is it old fuel or new?

 

[bukeyeocean]

Re: 1977 85hp Johnson not running up to par

He claimed that he tore the engine down to clean all of the water out, rebuild the carbs, and drain/replace all of the fluids. He also said that he drained the fuel and put in new. I would like to think that he did all of that.<br /><br />I drained all of the fuel out and replaced it with new this year. He had put some in it to test after he did the repairs.