Johnson 85 HP intermittant power issues

[bozman]

This does sound like a few of the other issues posted but I wanted to get a fresh look at it. I have had my motor for about 6 months and it has not given me any trouble at all (1975 model). Starts every time, Idles well , has plently of power. Last week I took it to get serviced and the plugs and oil were replaced ( they may have adjusted a few things I did not bother to ask). On saturday I took her out and the motor seamed to be a bit funny but still ran reasonably. Sunday turned into a nightmare. I topped the fuel up Sunday morning with fuel that I bought and mixxed that day. It started fine and ran at about 4500 rpm without any problems. After about 10 minutes it died and would not rev past about 2000 rpm. I stopped and check to make sure that all plugs were firing, 1 was not on the right side of the motor ( as you look at it from the back ). I did not have a plug spanner onboard so I could not check to see how the plug looked. Anyhow we decided it would be best to head back , after about 10 minutes of putting along at full throtle and only doing about 2000 rpm it burst back into life and happly reved to the usual 4500 rpm. This occoured a few times. When running at 2000 rpm it would occasional kick like a dead cylinder fired two or three time. It would occasionally idle ok and at others it would stall before you could get it into gear. I would have said that it had a foulded or bad plug but they only had about an hour on them. The other strange thing was that when I picked the boat up (after the service) I was told that it was only running on 3 cylinders. As far as I am aware it has never run on 3. I had it out 2 days before and it was a very happy motor.

 

[Walker]

Re: Johnson 85 HP intermittant power issues

Sounds like a bad coil of at least a bad ground to that coil.

 

[Solittle]

Re: Johnson 85 HP intermittant power issues

If I paid for a service on an engine that was running on 4 and after the service I was told that it is now running on 3 I think I would ask if they removed a cylinder to make it run better. Just kidding - - If they caused the problem then they should fix it at their expense.<br /><br />Beyond that if you decide to get into it yourself you need to do some troubleshooting before you start guessing and throwing parts at if. Check for spark to all cylinders and check the fuel system. There are plenty of posts here if you don't know how to do these things. Use the red search at the top of the page.

 

[blackwaterstout]

Re: Johnson 85 HP intermittant power issues

I just posted about my similar situation in another thread. The difference for me is that my motor is a 2 cylinder 25 horse. At first I thought I had a bad coil as well, but after swapping the two coils the same cylinder was sparkless. That was a pretty good indicator that the coils were fine, it was the power pack that had the problem. I ordered a new one today. Hopefully that fixes my issue. Maybe you should also try swapping coils to see if that is actually your problem

 

[bozman]

Re: Johnson 85 HP intermittant power issues

I origionally was going to just get the water pump thing replaced but ended up being taked into a service as well. I hate others touching my cars , boats or bikes as they normally come back worse or it just is not worth the money you pay. I used to be a mechanic but I do not have any experiance on boat motors so I thought that I would get an expert to look at it. Im in two mind about taking it back or just sorting it out myself. I hate that smug look that give you when they say , hmm its just a coincidence. Thanks for the advice. Either way Im going to pull that plug out tonight to see what is happening in that cylinder.

 

[bozman]

Re: Johnson 85 HP intermittant power issues

I pulled all the plugs and found that 3 of them appeared to be a bit used. They were a little wet and were a little dull. I wiped the surface of them with a dry cloth and found that they came up faily good. I would have said that they were fairly new. The last plug that I looked at was very shinny , it was like brand new, I would have thought that it had actually not done any work at all. It was not even wet ? Dont under estimate what I am saying, I have been working on cars for years and it looked like it was straight out of the bax brand new. Its a bit late in the evening to be starting her up but I will at some point and check to see if the miss is still there. If so I will check coil packs and spark again. I did speak to the guy who did the service, he could not remember me but was able to remember telling me that it origional was running on 3 when I brought it in. Strange that in the 6 months I have had it the engine did not miss a beat. I hate coincidence. Oh , he did mention that it would be hard to track down. I think I will cut my losses and do it myself.

 

[blackwaterstout]

Re: Johnson 85 HP intermittant power issues

Once agin Bozeman that is exactly what happened to me. My top cylinder plug had a little oil and I could tell it had been firing. It looked good. The plug in my bottom cylinder looked brand new. I knew at that point it hadn't fired any. A spark test confirmed it. <br /><br />What you should do is test the spark again. Then take a coil from a cylinder that is firing well and put it in place of the coil that isn't firing. If the good coil fires on the bad cylinder you know you have a coil problem. If the bad cylinder doesn't fire the good coil you know it's probably your power pack.

 

[bozman]

Re: Johnson 85 HP intermittant power issues

Thanks BWS , I will have a look at it tonight and let you all know.

 

[TD_Maker]

Re: Johnson 85 HP intermittant power issues

This is going to sound stupid, but please consider what I an suggesting. I used to have a 1978 115 Evinrude. I took off the top cover to check something, and replaced the cover again with a little difficulty getting it over the wires. When I fired her back up, it was only running at half speed.<br /><br />The engine cover latches caught the coil connector and pulled it apart just enough to cause the coils to not fire. Anyone who has had a Johnson/Evinrude knows what I am talking about.

 

[bozman]

Re: Johnson 85 HP intermittant power issues

I know what you mean they do stick up a bit from the power pack. For those who are following here is the latest. <br /><br />I removed the ht leads from the plugs with the motor running on muffs. I found that it was actually running on 2 cylinders. 1 and 4 were not firing. I removed the plugs to see if there was spark and there was not. I grabbed an old good plug and repeated the process and there was still not spark. I then swapped the coils between cylinders on the left back as you look at it from the back of the motor ( 2 and 4 I think ). You would not believe it but rather than the prolem staying with a cylinder or moving to another both actually worked and the motor reved to about 1500 rpm. I did not bother to check this on cylinders 1 and 3. I did not need to phsycally swap coil packs as I was able to swap the ht leads without too much trouble and I used a piece of wire with two aligator clips to extend the wire that did not reach on the power pack. So at the end of the day I am willing to say that it is an intermittant electrical problem. TD_Maker may well be right. Although I think that it may actually be on the HT leads at the plug end. I did notice that when I went to grab the plug leads with my insulated multi grips that the spark actually jumped threw the insulator and went via the multi grips. It had a very nice bright blue spark. Good thing I did not try removing them with my hands.

 

[bozman]

Re: Johnson 85 HP intermittant power issues

Hey Guys , where can I go to find out which powerpack and coils I need, just incase I come across some one who has some ?

 

[bozman]

Re: Johnson 85 HP intermittant power issues

Alls well that ends well. <br /><br />I took the boat back to the mechanic that origionally worked on it and he found that there was a small bit of something that was blocking the main jet for one of the carbs. I have had the boat out 3 times since and it has not missed a beat. Thanks to those who offered advice

 

[pj_elia]

Re: Johnson 85 HP intermittant power issues

Interesting, so it did not have a spark problem?