Logo
FULL SITE MENU

Oily rich Johnson 3hp

N

Nobrot

Contributing Member
HI Guys, Newbie with a problem here...I buy restore and collect 3 hp Evinrude/Johnsons and I have a problem. I have one which is almost restored with virtually everything new but it runs, or seems to run very rich and oily. It starts without choke and only runs at low revs with lots of smoke and an oily residue below the water/exhaust ports on and down the lower leg. The only time it runs sweetly is when I turn off the fuel tap to run her out of fuel and then it's for a few seconds till she stops.
To aleviate the problems so far far I have

Cleaned the carb twice with new O rings. Still using the original cork float but new needle and seat ( but not the main bowl gasket nor the main high speed needle which is more like a bolt with no tapering )I haven't a new one in yet
Changed the top half of the carb with another one but again no gasket or main needle
Changed the main internal jet
Checked all the electrics, plugs and points again
Checked the fuel ratio twice even ran her on 100/1 just to make sure it wasn't the mixture.
Checked exhaust for blockage
Checked the carb connections etc etc

I'm so close to getting back to her former glory but this has me stumped

Any idea....thanks
 
Hello, that is really nice motor, i have Evinrude 3hp 1966, which i have rebuild from zero. First it might be good to know the year of your engine? Since older ones had adjustable high-speed jet, and it is important that this adjustment is right. My 66 model, only have low speed adjustment. I use 24:1 mix, and engine works just fine. Are you sure that float level is right? it could be, that old float is not float anymore, and lets too much gas run to the carburettor.
 
Evinrudemen said:
Hello, that is really nice motor, i have Evinrude 3hp 1966, which i have rebuild from zero. First it might be good to know the year of your engine? Since older ones had adjustable high-speed jet, and it is important that this adjustment is right. My 66 model, only have low speed adjustment. I use 24:1 mix, and engine works just fine. Are you sure that float level is right? it could be, that old float is not float anymore, and lets too much gas run to the carburettor.
Click to expand...

I'll check it but it's the cork one so ' should be Ok ' I have spares. As you mentioned I'm not 100% sure about the main jet or lack of jet..I'll check the year and post it.
Thanks.
 
Confused. You say you changed the "main internal jet". But you also mentioned the main high speed needle looks like a bolt. Say what???? A high speed needle certainly should not look like a bolt. But there is a bolt plugging the hole where the fixed high speed jet goes. Methinks you have an accessory adjustable high speed kit. But it shouldn't look like a bolt.

Got any pictures?
 
fdrgator said:
Confused. You say you changed the "main internal jet". But you also mentioned the main high speed needle looks like a bolt. Say what???? A high speed needle certainly should not look like a bolt. But there is a bolt plugging the hole where the fixed high speed jet goes. Methinks you have an accessory adjustable high speed kit. But it shouldn't look like a bolt.

Got any pictures?
Click to expand...

Main internal jet...brass tube, 6 holes screwing in vertically, screw thread dipping into the bottom of the bowl. The high speed needle, horizontal needle screwed into the bottom of the bowl, does indeed look like a bolt whereas in the others I have are tapered needles. This one is basically a 11mm bolt without a taper about 20 mm long. I'm beginning to think this is where the problem lies.
 
Nobrot said:
Main internal jet...brass tube, 6 holes screwing in vertically, screw thread dipping into the bottom of the bowl. The high speed needle, horizontal needle screwed into the bottom of the bowl, does indeed look like a bolt whereas in the others I have are tapered needles. This one is basically a 11mm bolt without a taper about 20 mm long. I'm beginning to think this is where the problem lies.
Click to expand...

What you call a main internal jet is what I would call a main nozzle. Nevertheless, you are correct, that is where the problem is (bolt). Check the parts list for whatever year your motor is. As I suggested, some use an adjustable needle and some use a fixed jet (called an orifice plug)
 
racerone said:
Why would you run one of these on 100:1 ratio ??----What where you trying to determine in doing that ?
Click to expand...

Judging by his post he was looking to see if mixture made a difference. Albeit, not the right test. Sounds like he knows the issue, from looking through the discussion.
To the OP, post all the motor info. And some pictures of the suspected problem. Will help to diagnose.
 
racerone said:
Why would you run one of these on 100:1 ratio ??----What where you trying to determine in doing that ?
Click to expand...
Just to see if it actually ran better on an oil lean mix and to eliminate any fuel mixture doubts. Only ran it for a few seconds, still very smokey although that could have residual oil in the bores etc etc.
 
As far as I can work out she's a 1967 ( folding longshaft ) and the ' bolt ' has a different thread to a normal high speed needle so I may well have to borrow a fully working carb of one of my others to see if that solves my problem and then go from there..

johnson carb 002.JPG

johnson carb 003.JPG

johnson carb 006.JPG

A bit blurred but you can see
 
The meaning of the bolt, it helps you to drain the carburettor, example for winter. I like that design. After all, i highly recommend to put new float to carburettor. Old cork material can crumble and this only lead troubles. I attach photo of my carburettor here, just for help example when setting the new float for right level. During rebuild, i put all new gaskets,float,float needle and seat. There is also seal-ring under the needle seat.

carb.jpg
 
That is the drain plug with provision for a spring for front cowling.-----The fixed high speed jet is way inside that drainplug hole.
 
Yes sure i remember i saw it there. I did not do anything for it, during rebuild. Only sprayed carb-cleaner throughout it
 
racerone said:
That is the drain plug with provision for a spring for front cowling.-----The fixed high speed jet is way inside that drainplug hole.
Click to expand...
Oh bugger.... runs out to the garage and checks........
You're right, hiding down the thread and barely visible. Modified a screwdriver to try and remove but it's tight in and feels like it's brass. Put in sonic cleaner for while and left. It didn't seem blocked though.

Thanks for that. Will keep you posted.
 
Now you're getting somewhere. One more thing to consider. Some misguided individuals will replace that brass orifice plug with one with a larger hole OR run a drill through the original, both with the incorrect idea that more gas makes more go. That theory just isn't true.
 
fdrgator said:
Now you're getting somewhere. One more thing to consider. Some misguided individuals will replace that brass orifice plug with one with a larger hole OR run a drill through the original, both with the incorrect idea that more gas makes more go. That theory just isn't true.
Click to expand...
That kind of makes sense. The hole is rather large and would appear therefore to allow a lot of fuel through and without a way of metering it ie a threaded taper a large amount of fuel would constantly sucked into the venturi. This may also explain the reason behind it running well for a second or two when the fuel tap is turned off just before it stops as the amount of fuel being drawn up would be reduced. Am I on the right tracks.......Will try a complete but different carb off an Evinrude tomorrow, if all goes well then I need a replacement carb or at least the bottom half ( float bowl and high speed needle valve )
 
Nobrot said:
That kind of makes sense. The hole is rather large and would appear therefore to allow a lot of fuel through and without a way of metering it ie a threaded taper a large amount of fuel would constantly sucked into the venturi. This may also explain the reason behind it running well for a second or two when the fuel tap is turned off just before it stops as the amount of fuel being drawn up would be reduced. Am I on the right tracks.......Will try a complete but different carb off an Evinrude tomorrow, if all goes well then I need a replacement carb or at least the bottom half ( float bowl and high speed needle valve )
Click to expand...

Update...have found a spare float bowl, the same configuation as the one I'm dealing with but the aperture of the jet is a lot smaller than the other one....should therefore reduce the fuel intake......fingers crossed
 
Interesting thread. Ha.....you got it now. Somebody drilled out the jet on it.....Gator, was that your mention? Make sure that little donut gasket at bottom of nozzle tube, is making a good seal, otherwise unmetered fuel can be introduced into the nozzle......then it will run rich too.
 
timguy said:
Interesting thread. Ha.....you got it now. Somebody drilled out the jet on it.....Gator, was that your mention? Make sure that little donut gasket at bottom of nozzle tube, is making a good seal, otherwise unmetered fuel can be introduced into the nozzle......then it will run rich too.
Click to expand...

Well it would appear that way from what I can see. A big learning curve, thanks guys, as I didn't realise that brass jet was in there. Is it only Johnsons that have that as I dont recall any of my Evinrudes having that set up. Not out of the woods yet but I'll find out tomorrow and keep you posted. Again thanks to all concerned.
 
Johnson / Evinrude.----Same parts with different paint and decals.----Not all years used the fixed jet.----Fixed jet showed up first in the 63 model Johnson and Evinrude 3 HP.
 
Last edited:
Up date....2nd pull, runs like a dream and idles down to virtually nothing. Again, many thanks to you guys, I was totally unaware of that brass jet and it's saved me loads of head scatching. Now to respray and decals, find a space for her with the others and try to justify it to her indoors. Next project.....
Cheers.
 
Up dated up date......As above she runs very well, sort of. I ran her dry for a minute and all was good, put her in the tank and she ran rough. Took of the lower unit ( she's a foldable ) and ran fine for a minute out of water, all OK. Put lower unit back on and back in the tank....ran rough again. Seemed to be she ran rough when there was load on the prop so I took the prop off and ran her....ran well, so it seems she baulks under load and is still smokey, didn't notice as much smoke when she was running well out of water.
Conclusion so far....she runs rough and smokey in water with the prop on but out of water or with no prop she's fine......the prop also turns relatively smoothly when the bottom unit is taken off and it's the weedless prop......any ideas ??
 
If you ran it dry with no water to the impeller , you now need a new impeller.----Do you understand the concept / reason for the oil in the fuel ?----
 
racerone said:
If you ran it dry with no water to the impeller , you now need a new impeller.----Do you understand the concept / reason for the oil in the fuel ?----
Click to expand...

There was enough water/moisture in the system for the short time it was run for it not to be damaged and it did indeed work more than OK afterwards and regarding the oil in the fuel, I've always been lead to believe it was there as a colourant to help differentiate between the various uses of the fuel.:confused:
Anyway...
 
Back
Top