1962 18 hp johnson missing/backfiring

[coolguy147]

Re: 1962 18 hp johnson missing/backfiring

i say defiantely check ignition.

also make sure you set carbs needles with initial settings. 7/8 out high speed then 1 1/2 low speed. then adjust from there.

if it still lean pops with those carb then i do not know what could be wrong with it.

check for sheering flywheel key when you take the flywheel off.

replace fuel lines because cleaning the carbs wont do crap if the lines are sending rubber down to the carbs.

 

[mchin]

Re: 1962 18 hp johnson missing/backfiring

Are you sure your spark plug wire are correct. Maybe try switching them.

 

[bktheking]

Re: 1962 18 hp johnson missing/backfiring

Wouldn't run if they were reversed.

 

[tootallofwa]

Re: 1962 18 hp johnson missing/backfiring

How about the crankshaft seals? I saw a warning somewhere that if you hit your crank nut too hard trying to get the flywheel off, you could ruin your lower seal. Not to say that's what you did, but the top and bottom seals are important to maintain crankcase vacuum/pressure. Causing one cylinder to run different than the other, given same compression & spark.

Just a thought... :redface:

 

[Brianjason6]

Re: 1962 18 hp johnson missing/backfiring

I sprayed the intake with water while it was running to see if it would suck some up. No leaks. No unusual color either that would indicate a leak. The plugs are brand new again.. I bought another set yesterday just to check. The magneto components are all new..coils,point,condensers and crankshaft key. The points are set perfectly. The wires test with no resistance coil to boot and the spark is perfect. I did rebuild the carb again, complete with new packing again. The needles are sharp with no scoring. The carb is absolutely clean. The fuel pump is new. I tried running with the kill button disconnected thinking it might be vibrating and trying to kill the motor. Unlikely but I thought is was possible. No help. Head gasket is new. Compression is still reading 95 on each. My bulb and line is new. Fuel tank is cheap but hasn't failed before. I'm prone to think now that it may be the intake its self. I'm gonna lake test to runs some high rpms for a while and see if there is any difference. Even though it won't idle down low out of gear it does seem to run better in gear. I guessing it will be about a 2mph troll before it gets down to missing.

 

[Brianjason6]

Re: 1962 18 hp johnson missing/backfiring

I pulled the head off again and it looks oily. Also the gasket it wet all the way across. I'm assuming this new, used head I bought is probably warped. It wouldn't show up on a hand pulling compression test but may cause my problem. I thought I heard a hissing today when I ran the motor, yet the head bolts wouldn't tight anymore. I'm gonna try getting the head milled and another gasket. I'll let everyone know how it turns out. Thanks for the suggestions and help so far.

 

[bktheking]

Re: 1962 18 hp johnson missing/backfiring

Put it against a pane of glass and check.

 

[Brianjason6]

Re: 1962 18 hp johnson missing/backfiring

Put it against a pane of glass and check.

I have one other thought after triple checking all firing components, including plug gaps, points gaps, and ohm testing through to the wire boots. Fuel is pumping and reaching the carb. But I noticed today that when the slow speed needle was all the way in it didn't kill the motor. The needle looks good and I thought the hole it seats in looked good. Question is...Is it possible that the needle was once seated to far and instead of bending or scaring the needle it may have enlarged the seating port? Seriously, the needle looks perfect. It should kill the engine when it's seated. Somehow it's still getting plenty of fuel. This carb is spotless inside.

 

[Brianjason6]

Re: 1962 18 hp johnson missing/backfiring

As well the head seemed fine. I did get an omc gasket instead of the knock off this time and it looked slightly thicker to me. Anyway..Still not solved.

 

[bktheking]

Re: 1962 18 hp johnson missing/backfiring

The motor should die with that needle all the way in as far as I know. Take the needle out and shine a flashlight inside and look at where it seats, it may be enlarged.

 

[Brianjason6]

Re: 1962 18 hp johnson missing/backfiring

The motor should die with that needle all the way in as far as I know. Take the needle out and shine a flashlight inside and look at wear it seats, it may be enlarged.

I'll go look. Problem is I wouldn't know the difference. I've nothing to compare to.

 

[bktheking]

Re: 1962 18 hp johnson missing/backfiring

The needle has a taper, so should the area where it seats opposite the needle.

 

[Brianjason6]

Re: 1962 18 hp johnson missing/backfiring

I just saw that. I remembered having the parts motor and the tops of the carbs are the same. I soaked it for a minute and blew it out. Then brought it out next to my 62 and compared. The older one has a taper and the 62 just looks like a smooth hole. I believe it's just worn out. Unfortunately, I'll have to buy yet another carb kit to change the welch plug. I may just soak it and blow it a couple of times, then try it. Changing everything but the plug. I definately hope it works.

 

[bktheking]

Re: 1962 18 hp johnson missing/backfiring

They don't wear out cause the needle never makes contact with the taper, it's to meter air, closed would cause a super rich mixture hense why they need to be backed out ( on some carbs the needle can control both air and fuel) . What happens is people don't realize they can do damage when they seat it all the way with force. They are to be gently seated and backed out. If the inside of the carb you have has no seat in the carb anymore where that idle needle sits it has no way to meter air and just lets air in, more air than fuel=lean mixture which = no idle and pop pop pop.

 

[Brianjason6]

Re: 1962 18 hp johnson missing/backfiring

We'll all know for sure tomorrow. Reguardless of how I think it looks, I have no where else to turn for a solution. I've gotta try it to fix it or rule it out.

 

[bktheking]

Re: 1962 18 hp johnson missing/backfiring

PS- don't bother buying a whole new kit just for a welch plug, they probably have just the plug, use all the components from the old "new" kit.

 

[Brianjason6]

Re: 1962 18 hp johnson missing/backfiring

They don't wear out cause the needle never makes contact with the taper, it's to meter air, closed would cause a super rich mixture hense why they need to be backed out ( on some carbs the needle can control both air and fuel) . What happens is people don't realize they can do damage when they seat it all the way with force. They are to be gently seated and backed out. If the inside of the carb you have has no seat in the carb anymore where that idle needle sits it has no way to meter air and just lets air in, more air than fuel=lean mixture which = no idle and pop pop pop.

Are you ready for some GOOD NEWS? After soaking the old top half all night and half the day, I changed over the old choke parts to the newer ones. Then spray the carb out and blew it out with air. Put the old/new needle and packing back in, put in on the motor and....INSTANT SUCCESS. It's like a new motor. Idles down till you can barely see a bubble coming out of the water and it now reacts perfectly to the slow speed needle. What a lucky, lucky guess.

 

[bktheking]

Re: 1962 18 hp johnson missing/backfiring

Process of elimination my friend, there was no reason it shouldn't idle down, it would have out of the factory, it all pointed back to carb, glad it's fixed! You should post a new video.

 

[Brianjason6]

Re: 1962 18 hp johnson missing/backfiring

Here it is idling. I reved it up a little then brought it back to slowest idle. Nevermind the sound. The video is taken from a phone and the sound varies because of the phones auto noise suppresion. http://www.youtube.com/watch?v=9m4dFSW2Cr4

 

[restornator]

Re: 1962 18 hp johnson missing/backfiring

now is the thermostat there? That looks like an awfully large stream of water at idle.

sounds pretty good to me, also, i briefly had a 1962 18hp and the color changed to this aqua blue like yours. i wonder if Evinrude used some cheap UV damaging paint that year