Update to 62 Johnson 18hp---still runs the same as before, thinking fuel related ????

[edauth]

Well I had the original problem of hard starting after motor is warm, I changed points and condensors, and gapped coils and It did not change the way the motor runs. I will elaborate on my problem, the motor starts second pull first time on the water, runs good gets up to WOT good and idles with less throttle than when warm(closer to the slow mark rather than the fast mark when warm). My problem is after I shut it down it is very hard to start. I originally thought it was an ignition problem but now I think it is fuel, air/fuel related. I got on the water after changing ignition components and began to adjust low speed mixture, with the low speed set to smoothest idle and adjusting throttle stop to where it just stays running I looked at the roller in relation to the cam and roller is about 3/4 to 7/8 inch to the left (looking at it from the front) of the hash mark on the cam. (link and sync is good) any less throttle and motor dies. I dont believe this is normal but not sure. After gettin home I checked the low speed setting and it is about 1 1/8 turns out from seated, any richer and idle drops even more, and any leaner and motor dies. With where I have to have the throttle set at to keep at an idle the butterfly is open maybe 1/16 to 1/8 turn, shouldnt the motor idle with the throttle butterfly all the way closed which = roller to the right of the hash mark? Sorry bout the book and thanks for the help guys.

 

[Monte1961]

Re: Update to 62 Johnson 18hp---still runs the same as before, thinking fuel related

Sounds like you need to do a link and sync. the hash marks where the cam meets is where the carb/s start to open. Not before and not after. The motor will speed up from idle just by advance only in till cam meets hash marks on turn plate. The more the turn plate move at this point, the carb/s will also open more! Good luck.

 

[edauth]

Re: Update to 62 Johnson 18hp---still runs the same as before, thinking fuel related

I mentioned in first post that link and sync is good.

 

[AlTn]

Re: Update to 62 Johnson 18hp---still runs the same as before, thinking fuel related

at idle, the cam roller is on the timing cam and is located 3/4" to 7/8" to the left of the timing mark looking at it from the front?...at idle, the cam roller should be to the right of the timing mark on the timing cam. Link%sync should yield something like this...at the start position, the cam roller should be centered or slightly to the left of center of the timing mark < in this position, the throttle plate is just beginning to open> advancing the throttle <motor in gear> the roller should be on the highest point of the timing cam and the throttle plate horizontal in the carb throat at wot...with the link % sync set like this...at idle..the roller will be to the right of the timing mark and the throttle plate should be perpendicular to the carb bore

 

[edauth]

Re: Update to 62 Johnson 18hp---still runs the same as before, thinking fuel related

Yes you are right, at idle the roller SHOULD be to the right of the hash mark, but I cannot get the motor to idle at that throttle, which I believe to be part of my issue, basically I have to turn the throttle all the way towards the "neutral throttle stop" for it to idle when it is warm. Also, when I shut the motor down when hot, it is a PITA to start, sometimes I can get it to start by choking but the easiest way to start it is to put in gear and give it half+ throttle. I know that cant be right you shouldnt have to choke a watm motor to start it. This motor has kinda been a gremlin from the start, also how can I tell if the linkage between the roller and butterfly is correct length? I am stumped, like I said link and sync is good, low speed mixture seems to be where it needs to be( 1 1/8 turns out) any leaner and it dies any richer and idle drops even more. I just dont get it. Thanks guys.

 

[AlTn]

Re: Update to 62 Johnson 18hp---still runs the same as before, thinking fuel related

suggest this..as a temporary diagnostic tool...replace the pump to carb fuel line with a piece of clear tubing and watch for air bubbles as the motor runs..certainly a bad fuel mix will yield what you describle...the hot restart could be fuel, lack of fuel, lack of spark, overheated motor...I'd also suggest checking the spark when the motor is hot as a coil may be breaking down..possibly a plug wire has a bad connection at the coil or plug boot..starting at the beginning with a compression test, spark test, fresh fuel will help narrow down things

 

[edauth]

Re: Update to 62 Johnson 18hp---still runs the same as before, thinking fuel related

Ok I will try thos things, and check back in. Also what would cause air bubbles, and what do you mean by bad fuel mix? Bad gas or improper fuel/oil mixture? Thanks

 

[AlTn]

Re: Update to 62 Johnson 18hp---still runs the same as before, thinking fuel related

bad fuel...air bubbles could be bad fitting, cracked hose, internal leak in the fuel pump, any connection from the tank to the carb, cracked p/u within the tank

 

[edauth]

Re: Update to 62 Johnson 18hp---still runs the same as before, thinking fuel related

One question, what line do you speak of when you say pump to carb. My lines are: tank to pump, pump to sediment bowl, and bowl to carb.

 

[AlTn]

Re: Update to 62 Johnson 18hp---still runs the same as before, thinking fuel related

I'd suggest both the pump to sediment bowl and bowl to carb...also....check that the nozzle inside the carb is clear, unsure if you have really small holes in the nozzle, but if so, make certain these are clear

 

[edauth]

Re: Update to 62 Johnson 18hp---still runs the same as before, thinking fuel related

Where can I find this nozzle, is it the fuel inlet to carb or what, do I have to take carb off?

 

[AlTn]

Re: Update to 62 Johnson 18hp---still runs the same as before, thinking fuel related

go to marineengine.com...look at diagram for your year, hp., carb..part no. 56 .be careful cleaning this as they can get fragile with age...also check that the gasket part no.57 is in place...the carb bowl has to come off at least...looks aout as simple to remove the carb

 

[edauth]

Re: Update to 62 Johnson 18hp---still runs the same as before, thinking fuel related

OK I will check that, also the clear fuel line thing you told me to do, that will tell me if my pump is bad or is there a different procedure for that?

 

[edauth]

Re: Update to 62 Johnson 18hp---still runs the same as before, thinking fuel related

Checked compression, 98 on top 94 on bottom, is that acceptable? Will check spark in a bit when I have a helper(just checked-- spark is good turning it over on the trailer). Also if a coil would be giving fits when it gets hot, it wouldnt start at any throttle position until it cools down right? I can get the motor to start by giving it 1/2 to 3/4 throttle after I shut it down hot. And the nozzle you said to check I was thinking about it and the motor runs perfect when cold, its just when hot I have issues, now if this nozzle was plugged it would be plugged no matter if it was hot or cold, thats what makes me think it is not carb related but maybe fuel delivery. Maybe my logic is wrong here not sure though.

 

[edauth]

Re: Update to 62 Johnson 18hp---still runs the same as before, thinking fuel related

took the boat to the water today, confirmed good spark hot and cold(removed plug wires and motor died each time), confirmed good fuel supply(bowl stayed full), I am out of ideas guys, I think even though the carb was rebuilt a year ago I need to tear it down, any suggestions on this, I think there are only two jets-high speed and low speed, correct?.

 

[Monte1961]

Re: Update to 62 Johnson 18hp---still runs the same as before, thinking fuel related

Compression is good. After carb overhaul, run some seafoam through it and compression should come up some. Yes you are correct on the jets. Post back model # with your results! Good luck.

 

[edauth]

Re: Update to 62 Johnson 18hp---still runs the same as before, thinking fuel related

Well I took carb off and found the inside very clean, the high speed nozzle in the middle of the float was spotless, the high and low speed needle were in good shape, but I never saw the low speed jet or any other piece of the carb to take apart to access low speed jet, may need some advise on that one, but, I think the best news I have from taking the carb apart was after taking bowl off, removing high speed nozzle and inspecting the needles I picked up the carb and noticed something laying on the bench which I found to be a piece of the old cork float about 3/16 diameter which must have been left in there when I had the carb rebuilt by a supposed reputable mechanic last spring, on a side note the motor never ran right after I got it back from him and I am still fighting the same motor problem to this day, but thanks to you guys I am hopeful I can fix it without paying someone to do it. My hope is, that piece of cork was plugging some passage in the carb, so hopefully I can take it back to the water after work tomorrow and see what happens. Wish me luck guys and I will sure let you know what happens.

 

[AlTn]

Re: Update to 62 Johnson 18hp---still runs the same as before, thinking fuel related

go back to the carb diagram..part no.25 <expansion plug> needs to be removed < I use a sharp awl and rap it with a hammer..doesn't take much as this plug is ~1/8" thick...just pop it out > there's a small well under here with the idle circuit holes which open into the back of the carb throat behind the throttle plate. Get those small holes clean. You'll also see the end of the low speed mixture needle <hopefully>. Remove the needle and packing and clean that area spotless. Your carb kit should contain that expansion plug and new needle packing. Expansion plug installs convex side up and by smacking the center of it, it expands and seals. I use a 3/8's drive extension and hammer. You can put some fingernail polish or loctite around the rim of it if you're concerned about it leaking. Needle should be sharp and the top secret files contain info on how to adjust it.

 

[bouttime007]

Re: Update to 62 Johnson 18hp---still runs the same as before, thinking fuel related

Checked compression, 98 on top 94 on bottom, is that acceptable? Will check spark in a bit when I have a helper(just checked-- spark is good turning it over on the trailer). Also if a coil would be giving fits when it gets hot, it wouldnt start at any throttle position until it cools down right? I can get the motor to start by giving it 1/2 to 3/4 throttle after I shut it down hot. And the nozzle you said to check I was thinking about it and the motor runs perfect when cold, its just when hot I have issues, now if this nozzle was plugged it would be plugged no matter if it was hot or cold, thats what makes me think it is not carb related but maybe fuel delivery. Maybe my logic is wrong here not sure though.

The compression on my 62 28h was 80-85 when I first started out and it still runs fine to this day.


Maybe you are running a tad too lean and getting the motor hotter than it likes. 24/1 mix?

 

[edauth]

Re: Update to 62 Johnson 18hp---still runs the same as before, thinking fuel related

Took it to the river after work and problem seems to be fixed, I warmed it up and shut it down at least half a dozen times and started again with half a pull each time. So the apparent cause of my problem was a piece of old cork float stuck somewhere in the carb. Glad to have it fixed!!!! And cant thank you guys enough for all the help.

Also I am running a 75:1 fuel/oil mix using amsoil synthetic.