1976 85 hp Johnson

[mfergie112]

Engine runs very well for about 20-30 minutes. After that is like it has no power but idles good. Have changed all 4 coils, spark plugs . Also, replaced the rectifier after seeing the wires burnt. Also has a new water pump. Any help will be appreciated. Thanks

 

[rickdb1boat]

Re: 1976 85 hp Johnson

Have you tried pumping the primer bulb when this happens? Might also be a clogged fuel tank vent. Do you have spark to all cylinders after it slows down? Will it run again if you give it time? Did you replace the parts because of this problem or another? A little more info please...

 

[mfergie112]

Re: 1976 85 hp Johnson

Have new fuel lines, filter, and a primer bulb and don't seem to be losing prime. Also have changed the fuel lines to the carbs. Have not checked the fuel tank vent though. Haven't checked spark to cylinders while having this problem. Give it overnight, it runs fine again, then starts the problem all over again. 2 years ago it did this and i found cracks in 2 coils so i replaced all 4 and it been running fine until now. Could it be the power pack? Is there a way to check this? That's about the only piece left I haven't changed. Thanks

 

[rickdb1boat]

Re: 1976 85 hp Johnson

Well, without a bunch of testing equipment, you could run the motor in a tank or on muffs, heat up the powerpack with a hair dryer and see if you lose spark on any cylinder. If so, you've found the problem...Kinda basic, but it works...Easy way to check for spark when running is hook a inductive timing light up and move it from wire to wire until you find the one that's not flashing(Sparking)...

 

[mfergie112]

Re: 1976 85 hp Johnson

Ok, Thanks. Will check while having problem with the timing light. Will get back in couple days, thanks again for your information.

 

[mfergie112]

Re: 1976 85 hp Johnson

Well, without a bunch of testing equipment, you could run the motor in a tank or on muffs, heat up the powerpack with a hair dryer and see if you lose spark on any cylinder. If so, you've found the problem...Kinda basic, but it works...Easy way to check for spark when running is hook a inductive timing light up and move it from wire to wire until you find the one that's not flashing(Sparking)...

 

[mfergie112]

Re: 1976 85 hp Johnson

Have went ahead and changed the power pack, hope i wasn't jumping the gun. Still losing rpms after about an hour of constant running, but only after i stop and start again but seems better after i changed the pack as at least i can plane it out but lose about 1500 rpms. Acts like it wants to kick in but it don't. The tank vent is fine. The timing light shows i have spark on all 4 cyclinders while having the problem. As before, give it overnight and its fine again for about an hour. Thanks

 

[fireman57]

Re: 1976 85 hp Johnson

Check for overheating. If you are getting fire to all plugs then I would wonder about my temp. When the problem shows up hit the "choke" for a second or pump the primer bulb and see if that makes a difference. At least that would confirm or rule out a fuel delivery problem.

 

[mfergie112]

Re: 1976 85 hp Johnson

i have hit the chock and primed the bulb while having the problem but that didnt help either so pretty sure it isnt fuel. Motor does have a kinda ringing noise after awhile though, although not loud. How do I check if I have a temp problem?

 

[rickdb1boat]

Re: 1976 85 hp Johnson

The unofficial way is to hold your fingers on the engine head. If you can hold them there for a few seconds, it's probably ok. If it burns your finger or you have to pull it away immediately, then it's overheating...The official way is to use a thermomelt heat stick or a laser temp gun...

 

[mfergie112]

Re: 1976 85 hp Johnson

Is it ok to take the thermostat out to see if that's the problem on my temp? Also, where can I find an engine diagram for this engine? Can find a 1975 and 1977 but not the 1976. Thanks

 

[ezeke]

Re: 1976 85 hp Johnson

Parts diagrams for the 1976 85HP Johnsons are posted on the BRP Parts Manual site.

Copy the link to your browser without the quotation marks:

"http://epc.brp.com/default.aspx?brands=ej&lang=E"

 

[Freddy49]

Re: 1976 85 hp Johnson


You could remove the thermostat but only for a quick test not permanently, your engine will alway run cold and it is not good, but I suggest you test the thermostat instead of removing it permanently simply put it in boiling water and you will see, if it is opening.

 

[ezeke]

Re: 1976 85 hp Johnson

I would suggest that it is a bit of a chore to get to the thermostat on your motor, and that it has probably not been done for a while for that reason.

If you are going in there, get the gaskets and parts from you dealer first so that you can finish the job.

 

[mfergie112]

Re: 1976 85 hp Johnson

The BRP parts manual site doesn't have the cooling sytem diagram that I need, or at least I can't find it there. I'm new to the Johnson and not sure where the thermostat is. I bought this outboard just few years ago so to my knowledgs has never been changed and will get the parts to change it, just need to find it.

 

[ezeke]

Re: 1976 85 hp Johnson

It is shown at the top left of the exhaust housing diagram.

If you look down between the cylinder banks, under the two curved hoses, you can see the housing.

You can download the parts lists to Excel if you have it, and print the diagram.

 

[mfergie112]

Re: 1976 85 hp Johnson

Got it. Don't look that bad to change. Anything special need to look out for or change while i'm there? Does it take the kit or just the thermostat and gaskets? Thanks

 

[fireman57]

Re: 1976 85 hp Johnson

Just a lot of patience. Look for gunk that may have built up behind tstat.