Top end problem with a 4HP Evinrude 4206S

[monnewbie3]

Hey Everyone,

Intro:
I recently picked up a 1972 Evinrude 4206s outboard.

This motor needed new rings, so I tore the block apart and swapped the rings (one was seized), the cylinder walls were in really good shape, and swapped the gaskets.

Started 3rd pull, dialed the carb in so she runs very smooth down low, great for trolling.

Problem:
My problem is that there appears to be no top end on the motor. After about half throttle (very smooth until this point) it will rev then loses power (in about 2 seconds) and won't go any faster, it just sputters.
It almost seems to be a fuel delivery problem.. I swapped the primer bulb and hose since the old one was pretty busted up..
No matter what I do with the carb it won't go up on the top end.

I'm thinking about rebuilding the carb, but before I rip it open I want to ask you guys if I should look at anything else? (Plugs are new, properly gapped and give a good blue spark).

Thanks in advance!

-M

 

[hidef]

Re: Top end problem with a 4HP Evinrude 4206S

Clean the carb and replace the old fuel lines with alcohol resistant lines. The high speed jet is most likely plugged. Also check the filter screen in the fuel pump to make sure it is clean and not blocked.

 

[Rick.]

Re: Top end problem with a 4HP Evinrude 4206S

Clean the carb and replace the old fuel lines with alcohol resistant lines. The high speed jet is most likely plugged. Also check the filter screen in the fuel pump to make sure it is clean and not blocked.

Agree. This is the right place to start. Best of luck. Rick.

 

[dazk14]

Re: Top end problem with a 4HP Evinrude 4206S

+2 as noted above...

That motor has BOTH high and low speed needle adjustments. The high speed is the lowest needle and is often missing the knob.

If the needle seems stuck, loosen the packing nut a bit counter-clockwise. Gently seat and back out approx 1/2 turn. Set high speed on boat, a little richer is better than lean. Re-snug the packing nut.

It's possible the previous owner may have played with the adjustment in an attempt to get it running.

Good luck.

 

[freddyray21]

Re: Top end problem with a 4HP Evinrude 4206S

+2 as noted above...

That motor has BOTH high and low speed needle adjustments. The high speed is the lowest needle and is often missing the knob.

If the needle seems stuck, loosen the packing nut a bit counter-clockwise. Gently seat and back out approx 1/2 turn. Set high speed on boat, a little richer is better than lean. Re-snug the packing nut.

It's possible the previous owner may have played with the adjustment in an attempt to get it running.

Good luck.

if memory serve it only has a low speed adjustment. I think the high speed is fixed.

 

[Rick.]

Re: Top end problem with a 4HP Evinrude 4206S

Never rely on memory, at least when your my age. LOL. My 71 has hi and low adjustment needles. Rick.

 

[monnewbie3]

Re: Top end problem with a 4HP Evinrude 4206S

Thank a lot for all your replies!

This motor has both a High speed (top) and low speed adjustment(bottom), and both are working (well they turn anyways and effect the running of the motor).

The fuel filter is clean and the hoses aren't blocked, there's plenty of fuel coming out of the hose that connects to the carb from the fuel filter when i gently pump it.

I agree that is seems like the high speed, as it hesitates in and around the transition from the low speed jet to the high speed jet.
Is there anything I should focus on in the carb? I'm not to savvy about this carb.
http://www.boats.net/parts/search/BRP/EVINRUDE/1972/4206S/CARBURETOR/parts.html

There's a diagram of the carb from what I could find on the web. ^^

Thanks again,

M

 

[Rick.]

Re: Top end problem with a 4HP Evinrude 4206S

You have the needles crossed. High is on the bottom. If you order the Sierra carb. kit it does not come with a new float. OMC kit includes the float. Rick.

 

[monnewbie3]

Re: Top end problem with a 4HP Evinrude 4206S

You have the needles crossed. High is on the bottom. If you order the Sierra carb. kit it does not come with a new float. OMC kit includes the float. Rick.

yes yes your right, low speed = top high speed = bottom, just got them mixed up.

Is there anything I can clean to get this motor running again? or do I need a rebuild kit?

 

[Rick.]

Re: Top end problem with a 4HP Evinrude 4206S

We are only talking about the carb. needing cleaned and some replacement parts for it. You say the cylinders were good and you replaced the rings. What was the compression numbers after that work was done? If you prefer not to buy the carb. kit then you can tear it down and clean it and put the old parts back in it. If you have service records indicating when work was done and what parts were replaced then that's good enough. If you don't have records I would assume it hasn't been done until you verify otherwise. When I got my 71 I went over it top to bottom and replaced a number of parts I thought it needed. I hate being stranded on the water so I looked for potential problems and addressed them before hand. Since then I've had four years (and counting) of trouble free running with it. That's what I was after. Rick.

 

[monnewbie3]

Re: Top end problem with a 4HP Evinrude 4206S

We are only talking about the carb. needing cleaned and some replacement parts for it. You say the cylinders were good and you replaced the rings. What was the compression numbers after that work was done? If you prefer not to buy the carb. kit then you can tear it down and clean it and put the old parts back in it. If you have service records indicating when work was done and what parts were replaced then that's good enough. If you don't have records I would assume it hasn't been done until you verify otherwise. When I got my 71 I went over it top to bottom and replaced a number of parts I thought it needed. I hate being stranded on the water so I looked for potential problems and addressed them before hand. Since then I've had four years (and counting) of trouble free running with it. That's what I was after. Rick.

Thanks Rick,

I'll do a tear down this weekend, I'll order a rebuild kit but it won't be here for a while since I'm up in Canada, so I just want her going for the weekend and rebuild the carb the following.

Is there a specific jet in the carb that may cause this problem? Or a broken seal maybe?

 

[Rick.]

Re: Top end problem with a 4HP Evinrude 4206S

Where is Canada. Any Evinrude shop will have the kit. Rick.

 

[dazk14]

Re: Top end problem with a 4HP Evinrude 4206S

Thanks Rick,

I'll do a tear down this weekend, I'll order a rebuild kit but it won't be here for a while since I'm up in Canada, so I just want her going for the weekend and rebuild the carb the following.

Is there a specific jet in the carb that may cause this problem? Or a broken seal maybe?

If you want to fish this weekend... In a pinch, you can get these apart and back together without a kit.

Normally, it's the low speed circuit that's the headache. When it falls flat, have you pumped the bulb to ensure it's getting adequate fuel?

Where is the HS needle set to? Post back. Meaning turns out from LIGHTLY seated. There is not a lot of margin in getting the HS set correctly.

I can dust off the 1972 manuals in the morning, but the HS is VERY sensitive and will adjust out to within ~1/8" of the initial setting.


Edit: HS = High Speed

 

[monnewbie3]

Re: Top end problem with a 4HP Evinrude 4206S

If you want to fish this weekend... In a pinch, you can get these apart and back together without a kit.

Normally, it's the low speed circuit that's the headache. When it falls flat, have you pumped the bulb to ensure it's getting adequate fuel?

Where is the HS needle set to? Post back. Meaning turns out from LIGHTLY seated. There is not a lot of margin in getting the HS set correctly.

I can dust off the 1972 manuals in the morning, but the HS is VERY sensitive and will adjust out to within ~1/8" of the initial setting.


Edit: HS = High Speed

Thanks for the replies!

I've pumped the bulb while it's transitioning from low speed to high speed, while it was full throttle etc, to no avail.

The highspeed is set to approx .5 turns out. Anything less barely makes a difference, and anything more the engine runs rough.
The low speed is set to Approx 2 1/4 turns out, for trolling it works great at about 2 1/2 turns out.

Thanks again,

M

 

[Rick.]

Re: Top end problem with a 4HP Evinrude 4206S

Where is Canada. Any Evinrude shop will have the kit. Rick.

Hey sorry about that. I meant to say "where IN Canada" not "where is Canada". It still is pointing to a carb. issue to me. Clean it with a spray carb. cleaner both directions into every orifice and passage. Then spray it just as well with compressed air. Rick.

 

[monnewbie3]

Re: Top end problem with a 4HP Evinrude 4206S

Thanks guys, I'll clean the carb and see what happens

I'll check back after the weekend

 

[The Famous Grouse]

Re: Top end problem with a 4HP Evinrude 4206S

Did you change any of the fuel lines INSIDE the cowling? Not the main hose from the tank, but the smaller lines under the cowling?

If cleaning the carb and doing high speed adjustment doesn't do it, I would suspect an air leak in one of the fule lines. These can be difficult or impossible to visually inspect, so given the age of this outboard I would replace all lines. It's a cheap process and worth doing just for overall reliability, but it may also fix your problem.

Grouse

 

[monnewbie3]

Re: Top end problem with a 4HP Evinrude 4206S

Did you change any of the fuel lines INSIDE the cowling? Not the main hose from the tank, but the smaller lines under the cowling?

If cleaning the carb and doing high speed adjustment doesn't do it, I would suspect an air leak in one of the fule lines. These can be difficult or impossible to visually inspect, so given the age of this outboard I would replace all lines. It's a cheap process and worth doing just for overall reliability, but it may also fix your problem.

Grouse

Perfect thanks for the up! I'll probably do this as well!

 

[Haffiman]

Re: Top end problem with a 4HP Evinrude 4206S

A critical part in that carb is gasket #21 on your early link.
If that is cracked or not sealing properly, you will not be able to adjust properly with the high speed needle. Only .5 turn out, indicates it is leaking.

 

[monnewbie3]

Re: Top end problem with a 4HP Evinrude 4206S

A critical part in that carb is gasket #21 on your early link.
If that is cracked or not sealing properly, you will not be able to adjust properly with the high speed needle. Only .5 turn out, indicates it is leaking.

This is the information I needed, thank you very much! I'll be looking very closely at that o ring seal.

-M