The Johnson Curse continues...

[nymack66]

Re: The Johnson Curse continues...

Please check your Reeds very important and is not costly to do ...
Do you have a Tach and temp gauge installed? Important for benchmarking you will see the variations with every change you made.
Change the high speed jets back to 62D, on my 140 when I removed the 64d back to my stock (62d) WOT increased at lease by 500 RPM's and my running temp increase by or about 5 degrees with the 64d installed I was also loading up at idle and trolling and bogs at throttle up etc. Check your manual for the correct operating temperature for your engine. Mine is at 130/135 range give or take 5 degrees on water temperature and air temp on any given day.
I have dual probes into each cylinder head for accurate monitoring, buzzer in my opinion is useless, it gives you a static warning not a proactive warning where you can clearly see a rise in temperature or failure to run at the correct operating temperature, which is critical for a Outboard to operate correctly.
Also I am assuming your lower cowling and engine itself is clean and free of dust and loose foam from the inside of the cowling, recirculating foul and contaminated air will get sucked into your carbs clogging the idle and intermediate jets, use a air compressor and blow it clean you can also use a can of compress air and blow the air jets out,for your next rounds of testing. Notice you do not have air filter? We focus on clean gas and sometimes over look the other ...
Keep us posted..

 

[ondarvr]

Re: The Johnson Curse continues...

Have you checked to see if the primer system is leaking fuel.

 

[Craig-]

Re: The Johnson Curse continues...

It has ran fine at WOT and ran fine at an idle since the rebuild, but not necessaraly at the same time. There has been a problem between idle and WOT the whole time since the rebuild. Generally a stumble/bog/stall when going from idle to WOT, which seems to be from the carbs "loading up". Idle for a few seconds you can hear it and see the rpms drop until it cuts out. If you do not idle or rev it up it will plane out without stumbling or bogging. It has been supressed to the point at times it was tolerable, but just seems to get worse and worse.

What was compression check after rebuild?
How much time did it take to get down to 90-100 as second shop said?

 

[Dhadley]

Re: The Johnson Curse continues...

Ok, "it ran great before the rebuild". Then why did someone rebuild it?

Those motors will not run and / or cool right without t-stats.

Good choice on plugs. What grade fuel are you using?

Get rid of the electric pump and get back to the OE pump.

 

[Nathan S]

Re: The Johnson Curse continues...

It was rebuilt because of ring dowel migration on #3. Came out and broke the rings.

Initally when I got it, it didn't run with t-stats and did fine. I read on here that you shouldn't run without them, so I put them in and it blew up the next day.

The block has the Marfab cooling mod and new thermostats.

Fuel is always 87.

The general conscensus on these motors that I have heard from several places is that they do not make but around 100psi in compression. When I checked it immediately after the rebuild they were all around 100 psi.

Yes, there is a tach. Before the rebuild it would run 6000 rpm. After it came back from the first shop it would run 6000 rpm, but it would get hot fast. Now I can only get it to 5000, but it will climb to 5500 after running on plane for a little. That could be from the high speed, because I put all the stock jets in before taking it to the first shop and now I have the 64d jets back in and the RPMs have dropped.


I have a temp gauge and alarm installed. I checked at one time with a lazer thermometer it idles around 135 degrees. It climbs when running, but I couldn't tell you the temp. The gauge I have doesn't read with numbers just colors. Idle is just under half way on the gauge, on plane WOT is just over half way on the gauge.

The fuel primer is not leaking.

The cowling is clean inside. I am not sure about an air filter, I would assume the Air Box would take care of that.

 

[Dhadley]

Re: The Johnson Curse continues...

Ah, the famous pin migration. Yes, if they run hotter than they should that will happen with OE or Vertex pistons. They were designed (with t-stats) to run a little hotter at idle and then cool off slightly as the rpm increases.

 

[nymack66]

Re: The Johnson Curse continues...

"The general conscensus on these motors that I have heard from several places is that they do not make but around 100psi in compression. When I checked it immediately after the rebuild they were all around 100 psi." All good here

"Yes, there is a tach. Before the rebuild it would run 6000 rpm. After it came back from the first shop it would run 6000 rpm, but it would get hot fast. Now I can only get it to 5000, but it will climb to 5500 after running on plane for a little. That could be from the high speed, because I put all the stock jets in before taking it to the first shop and now I have the 64d jets back in and the RPMs have dropped." Perfect this makes sense , I mentioned this ..


"I have a temp gauge and alarm installed. I checked at one time with a lazer thermometer it idles around 135 degrees. It climbs when running, but I couldn't tell you the temp. The gauge I have doesn't read with numbers just colors. Idle is just under half way on the gauge, on plane WOT is just over half way on the gauge." Now this is NOT kosher , The Temp on my engine drops at WOT and increase at idle per the manual what I am seeing is correct yours is NOT , Check water pump/poppet valve etc for restriction. Note this is not related to your loading up issue we are trying to resolve since at lease you are seeing 135 degrees and higher.

"The fuel primer is not leaking." All good

"The cowling is clean inside. I am not sure about an air filter, I would assume the Air Box would take care of that." All good, there is no air filter, I was just trying to point out the fact if dust is present you will eventually see in in your air jets ...

Please check your reeds and verify they are not chipped warp or leaking very important they seal properly. I am sure you inspected them during the re-build OEM's or after market ? During your jetting did the motor ever backfire this will ruin your reeds this is why you have to check regardless.
Very important if Boyseen reeds are installed you will need to jet down your idle -4 per manufacture recommendations .

 

[Nathan S]

Re: The Johnson Curse continues...

I did check the reeds before reinstalling them. They are OEM. I never had a backfire, but not to say a shop did not. I should see fuel spitting out of the carb(s) while it is running if a reed is bad, correct? Or is it necessary to pull them out?

The thermostats are new. The Water pressure is 20+ when running. With the modded cooling ports if you try to run it without thermostats (Just tried one time to check the temp) the hottest it will get is 90 degrees at idle. With thermostats like I said around 135. At about half throttle the temp gauge wont move, at WOT it climbs a little. If you back off of the throttle it will drop down.

 

[Faztbullet]

Re: The Johnson Curse continues...

Are you the fellow in Clarksville and have the carbs with the adjustable needles and the idle and intermediate jets?(needle is at 11 o'clock on carb)

 

[1Chief101]

Re: The Johnson Curse continues...

Hi Nathan,

Having a Johnson Curse of my own.... I just today received a CD ROM of the 1971-1991 Factory Service Manual in the mail and was reading your thread bafore I get to reviewing that CD... Just a few questions. Did you ever research and find a suitable (affordable) fuel pump? If so could you pass on that info? Secondly, I had a guy rebuild all my carbs (1985 Johnson 120) and it spits a very tiny bit of fuel out of the carbs. I will probably find it in the manual, but have you determined whether this is normal or not? BTW, my problem is stumbling and dieing when trying to go from idle to about half throttle. Curses!

 

[Nathan S]

Re: The Johnson Curse continues...

I have not researched the fuel pump yet, I have been pretty busy at work.

Fazt, I currently reside in Smyrna, but yes probably who you are thinking of.

The carbs are the 6 individual plastic ones. High speed jet at 6 o clock, fixed idle and intermediate jets around 9 o clock and the Idle mixture screw around 11 o clock. I will post a link to a diagram of the exact carb.

http://www.boats.net/parts/search/BRP/JOHNSON/1994/J200STLERK%201994/CARBURETOR%20AND%20LINKAGE%20-%20185%2C%20200%20SUFFIX%20%22K%22%20MODELS/parts.html

 

[Faztbullet]

Re: The Johnson Curse continues...

Yep that them POS carbs on the R & K models. The needle is really a air bleed adjustment for intermediate jetting,that why it has little to no effect when adjusting it at idle. A good starting point is 2 turns out off a light seat and leave em there and adjust with jet changes, better is to find a set of carbs off later engine with 1 piece air box and chunk those...

 

[Nathan S]

Re: The Johnson Curse continues...

Good advice. I will back them out and go back to trying some jetting.

 

[Macwrench]

Re: The Johnson Curse continues...

A few years ago a buddy of mine had fits with a johnson 40. He cleaned the carbs a dozen times, but no luck. Finally he gave in and overhauled it... the compressions where a little low and uneven. Afterwords, it still ran poorly. I helped him do some troubleshooting on the ignition, but still nothing.

Finally one day he figured it out. He had put the floats in upside down the very first time he cleaned them. Couldn't tell by the diagram, they would go either way. Also, when measuring float height, it worked out somehow. Go figure!

Hey, I'm just sayin'

Good luck on your repairs.

 

[Sixmark]

Re: The Johnson Curse continues...

Next time you have it running, try spraying some carb cleaner around the carb and intake area, use it sparingly and keep track of where you are spraying it. If you get a change in RPM when doing this then you have a leak that should be addressed.

If the motor was run extremely hot and lead to the pin migration issue, it could very well have been run hot enough to destroy gaskets and carbs with warpage, etc.