Is my Johnson 70hp running rich ?

[DAN M VAGOS]

Hi all I just got a new boat and a different engine that I'm not familiar with. It's a 1999 Johnson 70 and to me it seems to skip so I took a vid and showed a outboard tec and he told me some run smooth and some don't and I would need to drive the boat and see how she runs and if it comes up on plain. We'll the next day I did and it ran good but still seemed to skip but it was just d winterized so I don't know if it still needs to run more. After running it and driving it for 45min this is what the plugs looked like.

 

[DAN M VAGOS]

Re: Is my Johnson 70hp running rich ?

This is the video of it running on YouTube

 

[racerone]

Re: Is my Johnson 70hp running rich ?

That does not sound very good at all.------Start with a compression test.---See how #2 compares with 1 and 3 on these motors.

 

[DAN M VAGOS]

Re: Is my Johnson 70hp running rich ?

Comp test was done and was 145psi on all three

 

[DAN M VAGOS]

Re: Is my Johnson 70hp running rich ?

This a a vid after I ran it on pond for 45min. http://m.youtube.com/watch?v=mftlXWbld5k
The first vid was it still burning the fogging oil off.

 

[racerone]

Re: Is my Johnson 70hp running rich ?

Does not sound very good at all.---Might want to put a fan nearby to blow away the exhaust.

 

[DAN M VAGOS]

Re: Is my Johnson 70hp running rich ?

I checked the fuel filter and it was clean and no water was found. And yes I'm changing it anyway lol . It seemed to get right up on plain and only hesiteted for a slit second when I punched it. Also is there a way to clean any part of the cab on this engine without removing the carb ? I saw in the parts book that came with the engine that there is a needle valve behind the drain screw. I really don't want to remove the carbs but it looks like the top carb bole is leaking just a little.

 

[racerone]

Re: Is my Johnson 70hp running rich ?

There is a high speed orifice behind the drain screw---NOT adjustable.------Carburetors need to be taken apart for proper cleaning / inspection.

 

[Chinewalker]

Re: Is my Johnson 70hp running rich ?

Is the thermostat present and functioning? Located at the top of the cylinder head. Motor will run like garbage if it can't get up to operating temp.

 

[DAN M VAGOS]

Re: Is my Johnson 70hp running rich ?

I don't know if the thermo is in but it did run for a short time then the water come out of the tell tail. Also I'm running NGK plugs and I was just reading that the motor needs champion plugs.

 

[emdsapmgr]

Re: Is my Johnson 70hp running rich ?

I have a 92 70 hp model, a lot like yours. It never has been a smooth idler-a characteristic of a 3 cyl engine. Fortunately, your carbs have idle adjustment screws on each carb. That will let you adjust the idle mixture while the engine is running. Remember that all three of the carb's idle passages are connected to each other, so when you adjust one idle screw, it will affect the other two. So, take your time and adjust one at a time-expect to spend some time fiddling with the idle screw setups. You may be able to smooth it's idle out significantly. I'd also want to make sure the idle rpm's are set correctly. Yours may be a little low. Set the idle when the boat is floating normally in the lake, and it's in forward gear. Set it to 700-750 on that engine. (You can't set the idle on the trailer)

 

[DAN M VAGOS]

Re: Is my Johnson 70hp running rich ?

Thanks for the input. Witch one is the idle screw.

 

[emdsapmgr]

Re: Is my Johnson 70hp running rich ?

If you are going to work on the engine yourself, going forward, I'd recommend an original factory manual: outboardbooks.com

 

[DAN M VAGOS]

Re: Is my Johnson 70hp running rich ?

Ya I may just leave well enough alone. I did just put in the new plugs and maybe that will help. Also can anyone tell me can I easily remove one carb to change a bowl gasket. I won't touch any screws just the gasket. I just don't know if it can just come off and put it right back on.

 

[DAN M VAGOS]

Re: Is my Johnson 70hp running rich ?

If this winter will ever end I could have it on the water and really test it.

 

[wrmdunker]

Re: Is my Johnson 70hp running rich ?

I am a rookie compared to most of these guys. However with my 70 hp Evinrude I did buy the OEM manual, rebuilt the carbs by full removal and disassembly. Very easy to do. Take your time and lots of photos to help you reinstall. The shop in my area bills 1 hour per carb.

Looks like the plugs are right but I always use Champion. Yours should be QL78YC if you want to try them. Cheapest thing you can do.

As far as I know water should come out telltale almost immediately. Not necessary to have stat open to see this.

 

[DAN M VAGOS]

Re: Is my Johnson 70hp running rich ?

I'm hoping I can just remove the top carb and slap a new gasket in it or I will just let it drip till I get to it.

 

[emdsapmgr]

Re: Is my Johnson 70hp running rich ?

What is dripping on the top carb? An external carb leak?

 

[DAN M VAGOS]

Re: Is my Johnson 70hp running rich ?

The top carb bowl gasket I think. It dose not seem to drip bad but I can see oil fuel on the top 2/3 carb.

 

[emdsapmgr]

Re: Is my Johnson 70hp running rich ?

There is a reason I asked. My 92 3 cyl spits a small amount of fuel out of the front of the top carb every stroke. Very little- but it is noticeable. The fuel either gets sucked into #2, #3 carb when running, or drops to the bottom of the airbox where it gets recirculated into the bottom cyl via the airbox drain hose. It is a "normal" thing. The engine's crank oiling system/passage exits the block where the top carb mounts onto the intake manifold. The small outlet actually spits that small amount of fuel/oil out- as part of the normal oiling of that engine. It's darn unusual to me, but I was assured by on OMC master tech that it was a design feature. Can't help but think that engineer did not complete his thinking on this one, but oh, well. Cannot complain about how the engine runs, however-year after year.....