66 Johnson 18 hp hard to start

[flintcreek]

Guys, I have a 1966 FD20 18 hp Johnson bought it not running. First off sorry for the long story, but I have been working on this motor for a while. Compression is 120 on both cylinders. New Points, plugs, coils and wires, carb cleaned knocking out plugs and blowing it out. Now the problem is that when the motor is cold it is very hard to start, I pull on it till I fall out and have blisters on my hands and it will finally start. Once it starts it will then as long as it is warm start with one pull. When it is trying to start it sometimes pops out the exhaust. Any ideals? I did just link the carb with the timing mark on the cam, did not make any difference. My main problem with this motor for some time was the linkage to the carb that runs on the timing cam was the wrong length, so the timing was off and it would idol ok, but not run WOT without adjusting the carb while giving it gas. I carried it to a mechanic and he spotted this took the home made linkage off and put on the correct, so now it will idol and run WOT without adjusting the carb. He also adjusted my points. Up until this it had always started very easily. I had put the points in last year. Would this points adjustment make it hard to start? At my wits end.

Thanks,
Flintcreek

 

[Daviet]

Re: 66 Johnson 18 hp hard to start

So you are saying that since the mechanic readjusted the points it is hard to start?

 

[jbjennings]

Re: 66 Johnson 18 hp hard to start

My suspicion is that your choke is not closing fully. I had one do this same thing. If the choke is cracked even a little it will be doggone hard to start cold. There is a little nylon thingy that the choke pull slides through. If it doesn't create enough friction, the choke will be pulled back just a hair by spring tension and not be closed fully when you let it go. Check it, or try getting a friend to hold the choke pull out by hand all the way and see how it starts. If it's the choke friction nylon part that's missing or bad, it will start easily when a friend holds it out all the way and you pull the starter cord.
Good luck,
JBJ

 

[14ftgrumman]

Re: 66 Johnson 18 hp hard to start

Did you use the correct link and sync proceedure for your motor? It would be in the service manual. If you use a Sealoc manual, it will have the proceedure for a lot of carb types and you have to figure out which one is yours. If you have a factory manual, it will show yours alone, a lot simpler.

It does not sound like it's a points adj problem. It sounds like a carb problem. Go thru the carb again, soaking it over night in carb cleaner, and blow out with compressed air. Run a very fine wire thru the jets.

Then make sure that you use the correct link and sync proceedure.

 

[flintcreek]

Re: 66 Johnson 18 hp hard to start

Yes, since I got it back from the mechanic it has been hard to start. He tore the carb apart checked and adjusted the carb and points and put the correct linkage on from the carb to the wheel that runs on the timing cam. What do you think? I will get one of my sons to help me make sure the choke is closing all the way and give it a try in a few minutes.

Thanks for the fast responses.

Flintcreek

 

[Daviet]

Re: 66 Johnson 18 hp hard to start

Check the choke and make sure it is working properly. I would pull the flywheel and check the point gap and make sure they are set properly.

 

[flintcreek]

Re: 66 Johnson 18 hp hard to start

I used the correct link and sync, I have done several of these old Johnson motors in this year range. The mechanic is retired and does not work on alot of stuff but has worked on these old Johnsons all of his life nearly and has been very nice and consulted with me on this motor and helped me out. When it left his shop it was hot and cranking with one pull. I am going to try to get one of my boys to go out to the shop with me and hold the choke and see what happens. Some where on here I read where some one explained the difference between a timing and fuel back fire, but could not find it when I did a search.

Thanks again for the responses. Headed to the shop for a few minutes.

Flintcreek.

 

[flintcreek]

Re: 66 Johnson 18 hp hard to start

My son helped me to checking on the firing with a timing light and found the firing off by about 1" or more when you check it with a timing light. Adjusted the points with a test light to where they break at the right point. Sprayed a little fuel mix into the carb and pulled a couple of times and it fired off. I was then able to lean out the carb by about 1 round. Idols good and cranks with first pull when warm. It has been sitting for 1 hour, I am headed out in a minute to see how it starts cold. In the past let it set for one hour and it was almost impossible to start. I will update shortly.

Flintcreek

 

[flintcreek]

Re: 66 Johnson 18 hp hard to start

OK good news. After sitting for 1 hour it cranked with one pull and ran real good. Shut it off and cranked it 10 more times with one pull. I believe it is ready to go. Did a little experiment while it was cranking and running so good. I have been running it in a garbage can, with a fan blowing to take away the fumes. Shut the fan off and the motor starts running bad after about 1 to 2 minutes and goes dead. Turn on the fan and it blows away the fumes and it cranks with 1 pull and runs good for 5 minutes as long as the fan is blowing. I will from now on hopefully always when running in a drum have a fan blowing away the exhaust. This was something I had read about here on the forum, but today I proved it to myself and my son. Thanks for all of the help.

Flintcreek

 

[Daviet]

Re: 66 Johnson 18 hp hard to start

Glad you got it fixed, happy boating.

 

[flintcreek]

Re: 66 Johnson 18 hp hard to start

Thanks, I just posted up a link that really helped me get the points set right. This is a great site, this particular motor has given me a fit. Now it is time to move on to the next project either a 77 model 35 hp or a 56 or so 15 hp, both are Johnsons. Thanks for everyone's help.

Flintcreek

 

[Daviet]

Re: 66 Johnson 18 hp hard to start

You took the bait, hook line and sinker, you might as well move into the garage to be closer to your projects.

 

[flintcreek]

Re: 66 Johnson 18 hp hard to start

Ok went out to check it after sitting over night and guess what it was hard to crank again. Shot a little fuel mix into it and it cranked right up, went back into the house to think it over again. Well me and my sons were talking about what it might be and they both said choke. I told them both I have checked the choke and it was closing off fully. Well the 17 year old went out and then came back in betting me he could fix it for a coke, a cheap price. So he carried me out and showed me that the choke was not closing good. I called my self checking this....I have got to bend over further or start wearing my reading glasses when working on the motor. Anyway there was some play in the linkage where the brass lever type rod goes through the shoulder bolt. I put a lock washer on the shoulder bolt and tightened up the linkage and it is now closing off fully at the top. Thanks Daviet and JB I will check it again tomorrow after sitting over night, but I am sure this will have it fixed. Off to the store for his 2 liter Mountain Dew. Thanks for your time guys this is a great forum. I will make a short post tomorrow to confirm the fix, but I am confident.

Flintcreek

 

[jbjennings]

Re: 66 Johnson 18 hp hard to start

I'm glad you posted back----I was still thinking it was going to give you trouble. It's amazing what a difference a tiny amount of choke plate opening will chave on cold cranking. I, too, am confident when you get that plate closing right it will crank within 2 pulls cold. Every 50's and 60's OMC 18 hp I own will do this. Many will crank on the first pull cold with the choke on, even in 20 degree weather (cold here).
I'll bet you really like this motor now that the choke problem is solved.
Happy boating,
JBJ