1967 20HP Johnson - Slow at WOT

[lambertfam]

I'm new to this forum but it seems like a great place to start learning about a motor I recently started using. The motor and boat (14' aluminum Grumman fishing boat) were my dads which we used quite a bit when I was a kid. But they have sat for over 15 years now and I have been trying to get them working again so I can take my kids out on the water. I have a neighbor that worked for a marine repair shops "years ago" and he volunteered to help. Seems like he knows what he is doing but I'm at the point where he can't help any more and I'd like to learn myself.

We checked the spark (after some cleaning of the points it seems fine, we also replaced the plugs) and checked the cylinder pressure (he said they both had almost 100) replaced the gas tank, the line and the bulb, checked the rubber impeller and got it to run pretty good. Water comes out the discharge fine and it doesn't overheat. At first it wouldn't stay running without the choke on so we took the carburator apart and cleaned. We put it back together and I had it in the water last night. It runs pretty good but doesn't like to idle real low and at full throttle it doesn't seem like it goes fast enough. I took my dad out with since he has a better idea of what it was capable and he said the same thing, just felt slow. I'm not sure why but my neighbor took off the lean-rich knob that was on the front. I kind of think since it was put on there originally it should be there, but would that help? I'm more worried about the slow speed than the idle, but would like to try and fix both problems.

I'm going to buy the operator manual and repair manual but I need to confirm the year yet. I don't have the model number with me, but I'll get it tonight and maybe someone can confirm 67' for me.

Sorry for the long post, I hope I gave you all enough information. Hopefully your not all too rough on this newbie. What are your thoughts, or what can I try first?

Thanks,
Mike

 

[tashasdaddy]

Re: 1967 20HP Johnson - Slow at WOT

sound like the carb either did not get cleaned completely, high speed jet, or it needs adjusting. http://forums.iboats.com/showthread.php?t=167352

 

[Fuzzytbay]

Re: 1967 20HP Johnson - Slow at WOT

Did you just clean the carb? or did you actually put a new carb kit in?
Theres a chance that some "stuff" is lodged in the passage ways, and unless you remove the knock outs, you can't clean it correctly. Also on that motor, I belive the high speed jet is fixed. There could be dirt in one of the three holes along the jet, you can clean that out with a "actelene torch tip cleaner".
Thirdly, is it with a tiller arm, or on OMC controls. You may have to adjust the throttle cable to actually get it to fully open the throttle, you can check the linkage visually to see if it does open up all the way.

 

[lambertfam]

Re: 1967 20HP Johnson - Slow at WOT

Thanks for the replies.

My neighbor said that he cleaned the carb so it's possible it didn't get done the best. Would you recommend buying one of the rebuild kits and doing it again?

I'm pretty new to this boating and outboard stuff so please bear with me. When you say "tiller arm" I'm assuming that's what I have since I have to twist the motor with an arm that is attached to the motor and the motor is not connected to anything linkage. I twist the handle to increase the RPM.

I took it out again last night and it did not go well. I only got to run it once for a short while and then it stopped and I couldn't get it to run longer than a few minutes after that. When I pumped the bulb fuel came out from the connection of the hose to the fitting on the motor. I'm going to replace that connection first, but is it possible that there is a block in the fuel line that goes from the connector to the carb?

How do i test spark on this? Can I remove a plug, touch the base to some metal on the head and pull the string? What should I look for?

How do I test compression? Do you put a pressure gage in the spark plug holes and pull the cord a few times?

 

[ftltony]

Re: 1967 20HP Johnson - Slow at WOT

Thanks for the replies.

My neighbor said that he cleaned the carb so it's possible it didn't get done the best. Would you recommend buying one of the rebuild kits and doing it again?

I'm pretty new to this boating and outboard stuff so please bear with me. When you say "tiller arm" I'm assuming that's what I have since I have to twist the motor with an arm that is attached to the motor and the motor is not connected to anything linkage. I twist the handle to increase the RPM.

I took it out again last night and it did not go well. I only got to run it once for a short while and then it stopped and I couldn't get it to run longer than a few minutes after that. When I pumped the bulb fuel came out from the connection of the hose to the fitting on the motor. I'm going to replace that connection first, but is it possible that there is a block in the fuel line that goes from the connector to the carb?

How do i test spark on this? Can I remove a plug, touch the base to some metal on the head and pull the string? What should I look for?

How do I test compression? Do you put a pressure gage in the spark plug holes and pull the cord a few times?

1. Yes, that is the tiller arm.

2. You NEED to change the connector. Your engine could be sucking in air instead of gas from the tank. It has to be a closed system from the pickup to the carbs.

3. In addition, after you have the cover off the motor, do you have an inline fuel filter? Check the fuel line with the cover off and look for the filter. If you have one, take it off and blow thru it. If you can't blow thru it "freely", get a new one, that one is clogged. Check this BEFORE you head to buy a new fuel connector in case you need a new filter and you can get both at the same time.


4. Your spark test is what everyone does with a few modifications but yours will work all the same. Look for spark!!!!!

5. Get a compression tester from an auto parts store that goes up to 100+ psi. Call the Evinrude dealer in your town and ask what is the right compression for your motor. Screw it onto the holes and pull the cord.

If you have a manual start motor, the spark test and the compression test is best done with someone checking hte gage and someone pulling the cord.

 

[lambertfam]

Re: 1967 20HP Johnson - Slow at WOT

Wow, thanks for the fast response.

I have had the cover off and I don't ever remeber seeing a fuel filter? I should probably get one of those along with the connector.

If I wanted to replace the gas line from the connector to the carb is there anything special about the line. Or can I get that at the auto store as well?

I'll let you know what I find out.

 

[tashasdaddy]

Re: 1967 20HP Johnson - Slow at WOT

make sure the connector was completely locked on before changing. they will sit there and the clip not be connected, and leak. also the hose end has o rings, which do go bad, and leak, i would try another fuel hose, before connector on the motor. there is nothing in the motor side of the connector to go bad.

the fuel filter is built into the fuel pump. remove the center screw, carefully remove the cap, look out for the O ring. there is a screen there that is the filter, you can remove and clean.

 

[lambertfam]

Re: 1967 20HP Johnson - Slow at WOT

Great thanks for the info. I'll take a look at it tonight or over the weekend. I did notice that when I locked the fuel hose onto the connector on the motor it locked ok but didn't seem like it was pushed in all the way. Almost like the hook that the hose connector fits onto wasn't holding it in the correct position. Since it was so old I replaced the hose and bulb but used the same fittings that were on the old fuel line. I'll check the o-ring before I replace the connector.

 

[tashasdaddy]

Re: 1967 20HP Johnson - Slow at WOT

did you replace it with a original Johnson hose or an aftermarket hose. there are some aftermarket that say johnson/evinrude, suzuki. which do leak, they are a slight different diameter. the suzuki connection is just a squeek larger.

 

[lambertfam]

Re: 1967 20HP Johnson - Slow at WOT

I replaced it with a gas line that I got from a small engine repair place. I used the old ends, just put new clamps on. The leak is between the connector on the motor and the connector on the end of the gas line anyway. As long as I'm not leaking arond the hose and the connector I figured it would be ok.

 

[lambertfam]

Re: 1967 20HP Johnson - Slow at WOT

I replaced the fuel line connector and now when i pump the bulb, fuel doesn't squirt out any more. Also, checked the compression, had about 115-120 in both cylinders after a few pulls. Pulled the plugs, grounded them and they both had spark. I did notice though that the top one was golden brown with not a lot of build up but the bottom one was black and more gumed up. What would cause this?

Took it out again today and had the same problem, just wouldn't go with the throttle all the way open. The engine was smooth just not pushing the boat as fast as I think it should. Also doesn't like to idle low either. Otherwise when in low to medium throttle it seemed to run pretty smooth.

I'm going to get a carb re-build kit. Any other ideas or things I can try? Could the prop be slipping? This model has a lean-rich knob that my neighbor took off saying it wasn't really needed. Would it help to have this?

 

[lambertfam]

Re: 1967 20HP Johnson - Slow at WOT

I would like to replace the fuel pump on this motor. I was talking to my uncle who knows a lot about small engines and he recomended this because the diapram inside the pump might be bad after sitting for 16 years. I looked on this web site and some others but can't find a fuel pump for this motor. Anyone know of other sites that might have a 1967 20HP Johnson fuel pump.

By the way I rebuilt the carb and I am trying to get it all put back together either later tonight or tomorrow morning. I cleaned out the high speed jet but could not get it removed. Hopefully it will be ok. It is also not adjustable so how do i adjust the low speed jet?

 

[lambertfam]

Re: 1967 20HP Johnson - Slow at WOT

Ran the boat this weekend with the cleaned carb and it seemed better on the trip out. It still didn't seem like it went fast enough though. But when I started it back up to come back to the dock, it was really slow just like it was before I cleaned the carb. Any ideas?

How do you measure the RPM of the propeller?

 

[kbd9]

Re: 1967 20HP Johnson - Slow at WOT

i have the same motor, i put a spark plug tester on my plugs and found one not making a spark. but when i touched the bare part on the tester when it was running it gave a little tingle, but not enough that it hurt. so in short, it made me look deeper. i found that the magneto to that spark plug was not close enough to the fly-wheel. so i adjusted the magneto closer and it runs great now. so that might be why it won't idle or run at W O T. later. KD

 

[viciousfishes]

Re: 1967 20HP Johnson - Slow at WOT

How did you get the flywheel off? Mine is stuck on there pretty good

 

[kfa4303]

Re: 1967 20HP Johnson - Slow at WOT

you'll need to use a harmonic balancer puller. you can get them from most auto parts stores for $15-20. Make sure you also get 3 GRADE 8 bolts to use with the puller as the ones that are often included in the kits are not strong enough. The bolts are probaly 1/4" - 20 and are readily available at Lowes. Home Depot, etc... Here's a picture of a basic harmonic balancer puller. hope it helps.

http://www.toolaus.com.au/catalog/images/13pc Harmonic Balancer Puller.jpg