1992 Johnson 90hp - still won't start

Bozol

Seaman
Joined
Jul 24, 2007
Messages
70
Hi all,

My motor started ok during the warmer months of the summer, not great (i.e not first turn of the key) but after a couple of minutes it would eventually start. However, now its fairly cold where I live (4'C/39'F during the day - Inuvik, Northwest Territories, Canada) and the engine only turns over if there's gas actually placed in the carbs and that's now not even a guarantee.

- Ignition is fine
- starter isn't great, but is good enough to spin the fly-wheel. Mechanics have told me its fine (one of the magnets had a small piece break off which required a cleaning, but its fine now minus the small piece. I don't think its the starter)
- fuel pump is brand new and all the lines from the gas tank and to the carbs are clear
- carbs were checked by a mechanic. He said they didn't need a re-build or cleaning. I have no idea when the last time that was done. Once I had the engine going put an entire can of carb-cleaner through it. The engine did sound smoother afterwards
- getting plenty of spark - coils and plugs are all new
- no choke on this motor, but a primer. Replaced with a new one. New primer shoots plenty of gas. I think the old one was fine.
- idle throttle: cable is tired and does not open throttle up all the way. However, taking the cover off and moving it with my hand does not seem to affect the starting process
- battery is always fully charged (I have two and when one gets tired from all the starting it gets switched with one that has been on the charge)

Starting procedure: I was never told an 'appropriate' starting procedure from the previous owner and have read many variations. Currently I turn the key so the battery is on, push the key in to engage the primer (I've tried holding it for 8 seconds, pushing it in and out a couple of times, not holding the key in etc...), turn the key all the way to engage starter (tried keeping key pushed in to engage primer, not pushed in, push in and out etc...).

As I mentioned before I can get the engine started in the driveway with the muffs on only after pouring gas into the carbs with the airbox removed - never first time success, usually 5-10 minutes). Once I get the engine hot it starts on the first turn of the key. However, as soon as its cold it needs the boost again. Once the engine is running it goes like hell.

Any help would is always appreciated.

Cheers,

Bozol
 

jtexas

Fleet Admiral
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Oct 13, 2003
Messages
8,646
Re: 1992 Johnson 90hp - still won't start

I'm skeptical about the starter - unless you've done a spark test & seen all four jump a 1/2" gap while cranking.

"put an entire can of carb cleaner through it" - hope you don't mean that you sprayed carb cleaner through the carb throats. If you did, what happened was, it went straight into the the intake manifold without ever passing through any of the orfices, and cleaned all the lubricating oil off the cylinder walls.

There is no way for a mechanic or anybody else to know whether the carbs are clogged without disassembling 'em...other words, you have to rebuild it to see whether it needs rebuilding.
 

Bozol

Seaman
Joined
Jul 24, 2007
Messages
70
Re: 1992 Johnson 90hp - still won't start

There is plenty of spark coming off the plugs - I've a new starter on the way however (don't want to rely on a broken one, should be here next couple of days).

I am going to order the re-build kit and do it over the winter, then see what happens next spring.

I put about 1/3 of the can of carb cleaner straight into the carbs (i.e. without airbox on), then put the airbox back on and sprayed the rest through the air intake. Plenty of mixed (50:1) gas was going through - should I be concerned (I'm confused about the difference between shooting the cleaner straight vs. through the air intake re: damage to the carbs themselves).

Could bad gas also be a culprit here?

Bozol
 

jtexas

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Messages
8,646
Re: 1992 Johnson 90hp - still won't start

Through the "air intake" is the same as straight into the carb throats - the engine just sucks it right in. The "intake manifold" is between the carbs and the engine. The orfices that need cleaning are between the carb bowl and carb throat; spraying cleaner through the throat doesn't clean anything in the carburetor. Carb cleaner is designed to break oil down and prevent it from sticking to metal surfaces. I'm not saying your carbs are bad, just that you haven't ruled it out.

Seems unlikely for bad gas to only affect a cold engine.

Cold start procedure is to turn the key "on" & hold it in for five or eight seconds and continue holding it in while turning to start. Are you lifting the high-idle lever full up?
 

Bozol

Seaman
Joined
Jul 24, 2007
Messages
70
Re: 1992 Johnson 90hp - still won't start

Idle throttle has been at various positions. The cable doesn't currently open the throttle full, but I have tried various different throttle levels with the cover off using my hands.

The carb cleaner they sold me is an aerosol - how are you supposed to get it into the engine if not through the air intake? Do you mix it with gas and start the motor? I've read that some jets are near impossible to clean short of an acid bath or a rebuild.

Bozol
 

HighTrim

Supreme Mariner
Joined
Jun 21, 2007
Messages
10,486
Re: 1992 Johnson 90hp - still won't start

the carb cleaner you have is for cleaning while off the motor during a rebuild. Never spray it or starting fluid into your carbs while running, use premix only! Take the carbs off, bath them, clean and rebuild. The high speed jets may need to be removed, you will need a specially made tool for this. Soaking them alone probably wont cut it. Wire may work to free up alot of the gunk before blasting them with the aerosol cleaner or compressed air.
 

jtexas

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Re: 1992 Johnson 90hp - still won't start

I use aerosol carb cleaner in place of compressed air, to spray through all the passages after the carb has been soaked overnight in carb cleaner.

The hi-idle lever will only open the throttle valves part way (maybe 15% or so?), more importantly it advances the spark. Make sure the timer base is moving all the way to its stop.
 

Bozol

Seaman
Joined
Jul 24, 2007
Messages
70
Re: 1992 Johnson 90hp - still won't start

Is it possible to buy carb cleaner in liquid form (i.e. not aerosol) for soaking?

Yesterday I took the hose from the primer to the carb off at at the primer end and blew as hard as I could - no sound came from the carb. I then reconnected to the primer and disconnected from the carb and pushed the key - plenty of gas came flying out. Then reconnected the whole assembly and listened while a friend pushed the key - no gas at all came into the carb. Can I be fairly confident my problem is glogged primer jets?

Bozol
 

iwombat

Captain
Joined
Jul 12, 2006
Messages
3,767
Re: 1992 Johnson 90hp - still won't start

It comes in a one gal can (paintcan) w/ a metal basket. You should be able to find one at the auto parts store.

The problem you describe indicates stuck or misadjusted float needle valves.
 

iwombat

Captain
Joined
Jul 12, 2006
Messages
3,767
Re: 1992 Johnson 90hp - still won't start

It's not specific to an outboard and the layout of the parts is odd, but this diagram from the wikipedia carburetor page will give you a better idea of the parts involved.

300px-Carburetor.svg.png


For the full write-up: http://en.wikipedia.org/wiki/Carburetor
 

Bozol

Seaman
Joined
Jul 24, 2007
Messages
70
Re: 1992 Johnson 90hp - still won't start

Wouldn't the engine run badly once started if the float needles were off? Once the engine gets going and is warm, the boat flies.

Bozol
 

iwombat

Captain
Joined
Jul 12, 2006
Messages
3,767
Re: 1992 Johnson 90hp - still won't start

If you've got sticky needles, the boat will have a hard time getting gas initially. Once you get going at 3/4 or better throttle the needles are open most of the time.
 

Bozol

Seaman
Joined
Jul 24, 2007
Messages
70
Re: 1992 Johnson 90hp - still won't start

I took the carbs off yesterday and they're soaking in carb cleaner. After a couple of hours I ran a tiny wire through the various jets and ports - all passed no problems except the primer ones (there are two sets of carbs, 4 cylinders). After another couple of hours I tried again and managed to unblock one of them and will try the second at lunch today.
 

iwombat

Captain
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Messages
3,767
Re: 1992 Johnson 90hp - still won't start

Did you manage to get kits yet, or no? It'd be good to pop the core plugs and clean underneath, but you destroy the plugs in the process. Is there a johnyrude dealer in Yellowknife or Whitehorse that you could at least order the plugs from?
 

Bozol

Seaman
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Jul 24, 2007
Messages
70
Re: 1992 Johnson 90hp - still won't start

I wont get the kits yet as it'll take probably 4-6 weeks to get here (there are dealers in both cities - I like the guys in Whitehorse myself - but due to the age of the engine they don't keep these parts in stock and have to order) and our season is just about over. It snowed 6 inches yesterday and is hovering around 0`C during the day. I will order the kits this winter, do the carbs, get the engine going and then sell it to help pay for a 4 stroke. Its a shame the boat dont go right now - prime moose hunting!
 

iwombat

Captain
Joined
Jul 12, 2006
Messages
3,767
Re: 1992 Johnson 90hp - still won't start

Those core plugs are the same size for a whole whack of motors. I'd be really surprised if they didn't have some handy. PM me and I'll send some up if you're having a hard time getting some. They're about $1 each if I recall.
 

iwombat

Captain
Joined
Jul 12, 2006
Messages
3,767
Re: 1992 Johnson 90hp - still won't start

Part #0202310 - core plug.
 
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