Johnson 120 issues.

[nymack66]

Re: Johnson 120 issues.

Please shed some light on the history of this motor, Did it ever worked perfectly at some point ? Did you purchase it and ran it for a while now these issues ? .......
The slip you mentioned could be a bad prop hub? Index the prop and test. It could be a high speed miss that gives you this slip illusion I have experience it ..
On the hose at home remove the air cover off the carbs and check for stuck floats (fuel gushing from the carbs) or excessive spitting (bad reeds or stuck float)
Keep us posted ..

 

[Leglav8s10]

Re: Johnson 120 issues.

Please shed some light on the history of this motor, Did it ever worked perfectly at some point ? Did you purchase it and ran it for a while now these issues ? .......
The slip you mentioned could be a bad prop hub? Index the prop and test. It could be a high speed miss that gives you this slip illusion I have experience it ..
On the hose at home remove the air cover off the carbs and check for stuck floats (fuel gushing from the carbs) or excessive spitting (bad reeds or stuck float)
Keep us posted ..

I bought the boat in the winter 3 years ago - this is my 4th season with it. The engine always ran good except it smoked a LOT. Other than this, it never missed a beat. I usually run on the river and have snagged logs (going slow of course) and ran in shallow water, but I never abused it or ran it hard. 4th of July a year ago I was pulling the cousins on an inner tube and the driveshaft snapped just above the pinion gear. Insurance Co. paid for a new lower unit which I installed. I did find out after swapping the gearcases that the g.c. on the motor when I bought it must have been an older unit as it had a 1pc driveshaft. I'm guessing it was replaced with a used unit which didnt get any internal work done to it.

The carbs dont spit anything, or very little. I never noticed anything. The carbs were rebuilt when I bought it - my personal request to the dealer. The dealer also installed a brand new SST stainless prop - never ran with that prop until I bought the boat. The "slip" is almost more of a jerk - doesnt seem like a dead miss to me. I can go from idle to WOT and it wont do it until you've been going for a little bit but it is a real rare occurrence. The engine never did this until the gearcase was replaced. However - this engine for whatever reason (I'm blaming the VRO) runs at about 30:1-35:1 fuel/oil ratio. It could be a miss, but after running WOT for a couple of miles, the plugs come out looking much drier than they did with the old plugs. I currently have QL82YC champ plugs in it now. I also have a set of QL78YC's that are new - I tried these first but they kept coming out covered in oil. The 82's have oil on them still, but not nearly as much. I leaned the idle mixture down a little bit on all 4 carbs. Idle is about 620rpm in forward gear. Compression is 130,135,130,137 in cyls 1,2,3,4. I expect the new fuel pump later this week and when I get it, I'm going to install it, and run the Engine Tuner through it and get it on the water and run it out and re-evaluate how it runs. I am very certain this fuel pump thats in it now is the original 1994 unit as the black plastic is very faded.

I was very careful with the new gearcase - the rep at OBR said the warranty doesnt cover worn out clutch dogs - I made sure it shifts properly before it went into the water so I don't believe its popping out of gear at all. I'm kinda shrugging my shoulders as it is so coincidental that it started doing this when the new g.c. went on. I was worried the g.c. might be defective.

sorry for another novel - I'm just being thorough.

Thanks
Tim

 

[Leglav8s10]

Re: Johnson 120 issues.

Okay.. little update.. I haven't had the boat in the water yet.. no time, but I did get a barrel to put the engine in to run it. I replaced the Thermostat diaphragms, and VRO pump. I went through every fuel system fitting and removed them, cleaned them, and sealed them with some high-temp thread sealing compound. I replaced the clamps on my fuel primer bulb with cinch clamps (the ones that came on it were junk), and did the same on the oil primer bulb. I replaced the spring clamps on the pulse fitting hose with cinch clamps as well. The engine now temps up nicely, doesnt misfire at all, and starts really well. I still have an insane amount of smoke, but I'm sure the crankcase is still full of oil from the bad pump. I pulled the air box off to see if there was any fuel leaking, and sure enough carb #3's float was too high - gas spewed out when you squashed the primer. I adjusted the float a little lower (dead level with carb body) and now doesnt spew gas. I ran out of daylight to test it this way, but when I take it out to go camping on the river I'll run it out and see how it does. I put a vacuum gauge on the fuel inlet between the bulb and vro pump before changing the VRO pump and got about 2-3" vacuum. With the new pump installed, I get about 1" vacuum with the engine idling. I'm amazed (even with the flooding carb) how fast it revs w/ the fast idle arm - its never idled up quickly like this... Hopefully after running it out this weekend, and running the engine tuner through it that the smoke will simmer down and it will run like a top.

Should you replace the impeller every year or can you go 2 seasons on the same impeller? I replaced the whole water pump assembly last year and havent changed the impeller yet this year.

 

[DaveBies]

Re: Johnson 120 issues.

Hello I am having a problem with my 1986 Evinrude 120 V4 VRO (oil injected); When I start it- it will not idle as it should or run at low RPM giving me a very jerking studder/fire... I have changed out the spark plugs, ohmed the spark plug wires at 1+ ohms; Changed all the fuel lines and filter; checked the carbs; and I also pulled out each sparkplug wire seperately as the motor was running and the engine stayed running the same and did not die;

Motor had not been used since '08 and after changing out all the fluids and giving it a good dose of seafoam each time I fuel It ran great for the first few times out on the lake; then the idleing low speed problem was intermitten; now I can duplicate it even out of the water with the water-muffs;:facepalm:

Could this be a problem with the power pack or the RECT/RGLTR?