'77 85 johnson troubles

[crherman]

Just found this site while looking for parts for my johnny. I'll make it sweet and brief. Just purchased from original owners son. Sat for about 7 years. Oiled the holes, new plugs, new gas and it pretty much fired off without a lot of trouble. On the water it runs great cold. Seems like when it warms, at higher rpms it will suddenly drop rpms to idle range and struggle to stay running. If I keep the throttle up high it will attempt to kick in off and on and then finally take of but with missing or attempts to low idle problem. When at its worst it does it at low rpms as well. I am rebuilding the carbs as I write but they seem pretty clean.(weird, as they sat for so long) but maybe the owner had them rebuilt in the past. Cant find out, dead, but they looked like thay have been off at least once. I'm wondering if this model has a derate ability if it detects a cooling problem. I did rebuild the water pump already. But I read it has a thermostat type system. Not familiar with it. Thats about as brief as I can make it other to say (what a gas hog) but it sure pushes this 18' cuddy around great. Thanks for any comebacks.

 

[5150abf]

Re: '77 85 johnson troubles

SOund slike a dirty carb, they can look factory new and be dirty.

Had a the same problem with mine, carb looked factory new but after I cleaned it she ran like a top.

Be sure to run a copper wire through the jets to clean them and get into the passage ways as best you can and use compressed air to blow it out, the air in a can works really well.

Just strip a wire and peel back wires till it just fits in the jets.

Don't know your engine but my 50 has an idle jet on the top front, a mid on the top back and the high speed jet is in the float bowl behind the drain screw, you need a long skinny screw driver to get this one.

Do one a time and keep the jets with the cover screw so you keep them straight, an idle jet doesn't work well in the mid spot, don't ask how i know that.

 

[emdsapmgr]

Re: '77 85 johnson troubles

Your engine has two thermostats, one for each head. The thermostat housing is the one below the powerhead at back that the two hoses go to. The thermostats keep the engine cool, but permits it to warm up to maximize combustion and economy. If stats stick open, the engine can run cool-which can cause other long term issues. You may want to get into that housing, since it is new to you and replace both stats and check the pressure relief valves. This is good, normal preventative manitenance. If you get the carbs cleaned and replaced and it still does not run right, you may have a spark problem. Weak ignition components tend run fine when cold, then fail when they heat up to normal operating temps. An inductive timing light on the plug wires will show which ones are sparking and which ones are not. Your ignition system does not have a derate capability. It does have an overheat warning horn.

 

[ezeke]

Re: '77 85 johnson troubles

There are two versions of the 1977 Johnson 85HP motor, one built on the older 1973-1976 V4 version and the other on the newer 1977 up.

Your model number will tell us which one you have. Locate it on the port transom bracket on a plate 1" X 3", or on a nickel-sized welch plug on the top of one of the cylinder banks.

The original ignition coils on these motors often break down when warmed up, and should be inspected. If they are cracked, swollen, discolored, or if the potting is deformed in any way, they should be replaced, as bad ones will damage the powerpack.

 

[crherman]

Re: '77 85 johnson troubles

You guys are a credit to the boating world. I have been on a lot of similar sites but have found none so ready to share knowledge and experience. For free, I might add. Thanks for all the helpful info and those that Im sure will follow. I have the carbs apart and going to get that kits through iboats. I like the wire through the jets trick (and laughed at jet experience). I knew I should have entered the model when I posted but forgot. 7785els. Seems like a late 77. Bummer I cant get a fuel pump kit for it but iboats has a great price on new pumps so I may go that way if problem persists after rebuild. The coils and stator all "look good", no discolor, melting, smelly, or cracks that I can tell. But I will check the spark test . Thanks guys.

 

[ezeke]

Re: '77 85 johnson troubles

You can navigate through to the parts catalog for your model here: http://shop.evinrude.com/

Your model has only one thermostat and has a water pump with two water tubes. It also uses the earlier gearcase with a skeg that has a rear line perpendicular to the propeller shaft.

The engine has water passage deflectors that may need to be serviced.

BTW, you can rebuild the fuel pump.

 

[crherman]

Re: '77 85 johnson troubles

Thanks for the info Ezeke. Went to the link you sent me. Did not find my model# under the 1977 85hp listings.**edit: Went back on site and discovered the drop down menu. I originally looked under Evenrude. DOH I got it goofed up in an earlier post. Its a 8577ELs. At least, thats whats on the port tag. But it does give me an idea of what I need and if I get into trouble I'll call em up on the land line (I think I still know how to use that thing). I am going to pick up a book on this thing as well. You got me scratching my head with:

" gearcase with a skeg that has a rear line perpendicular to the propeller shaft.
The engine has water passage deflectors that may need to be serviced."

Huh??? Is that where the bull shaft jumps the heffer gear?