Johnson 9R-70C

[wrmdunker]

My neighbor is new to outboards. He has a 1970 9.5 hp that was given to him. Said it ran fine last year. Now won’t start. He sprayed ether in the carb and it sparked for a second.
He was lots of quad runners......


He has good fuel, bulb gets hard. He checked the fuel pump screen and it’s clear.


I tried compression test but my tester bottoms out on the piston so could not screw in all the way and it leaked down immediately. On second though perhaps my stop valve on the tester leaked........


He must have spark since it popped. It’s in neutral and I played with the throttle position a bit to see if that helped and it did not.


He changed plugs. Put in J6C and manual calls for J4C but that should not prevent starting.

What next?

 

[wrmdunker]

And he was playing with the low speed screw and said he didn’t know what it was for....I turned it in and backed it out 2 turns. Is that a good place to start.?

i have a 68 3 hp and a 74 70 hp. I tinkered for 10 years now.

 

[racerone]

You have to answer this question.-----Does the spark jump a gap of 5/16" , yes or no ?-----Hearing it " pop " means nothing to me.

 

[wrmdunker]

Understood. I have a tester and it was just too bright to see plus it’s a pull start and the the motor was moving a lot. I know I need to get dark and I’ll set 5/16. What’s the gap on the plug. 0.30?

 

[racerone]

??----The gap on the plug is 0.030"---------A weak magneto can jump that gap with the plug laying on the block.------But it can NOT jump that gap with air pressure at say 100 PSI when plug is in the cylinder !!-----That has fooled many a novice and you end up with arms like " popeye the sailor " after a while.

 

[wrmdunker]

Might be insignificant now but any thoughts on the J4 vs J6 plug.
Yes, I’m a novice. Not denying that. I appreciate the advice.

I’ll be back later today.

 

[Tim Frank]

The J6s will get it started....then best to go with the recommended plug....unless your friend knows something that the engineers missed.

 

[racerone]

J4C for motors with a thermostat like the 9.5 models.-----J6C for motors without a thermostat.

 

[Crosbyman]

probably just needs a good carb clean I have fixed up 4-5 turtles and none ever went over 75 psi and all work good

have you ever pulled the flywheel to inspect the coils ?? if not they may be junk (cracked) see pic. of cracke coils on a 5.5.hp

if you do work the electricals may as well get new 7mm solid core wire plug boots coils condensers points

may as well do the impeler to !

see Leroys article on 9.5 upkeep

http://www.leeroysramblings.com/OMC_9.5.htm

http://www.leeroysramblings.com/johnson_magneto.htm

http://www.leeroysramblings.com/Outboard Motor Related/OMC outboard related articles.html

 

[wrmdunker]

Crosbyman, it’s my neighbors motor and he’s had it a year.

i think I could pull the flywheel. Do you know the torque spec?

LeRoy is awesome. He’s helped me on my 1977 9.9

 

[Crosbyman]

flywheel is about 40-45 ft lbs I would try a carb clean before openning the fw just my humble opinion

he had it a year but it is 59 years old :lol:

 

[wrmdunker]

49 actually but I get your point. I have Sea Foam, Deep Creep or do you think I should pull it and open up the carb. I talked to him last year about winterizing but not sure what he did.

 

[Crosbyman]

seafoam did wonders on my snowblower carb last winter … stopped my flame throwing backfires

you could try some . drain the hose..then the carb by openning the HS jet at the bottom and repump it full
use a gallon of fresh gas and half a can maybe

let it soak a bit

but openning the carb top portion is easy and you can blow some carb cleaner in every orifice you can access

visit utube for good videos on carb servicing

https://www.youtube.com/watch?v=r-VTkOuSg00
https://www.youtube.com/watch?v=Y2pwU5aho9U

yep 49 ...:facepalm: but….do check for strong sparks as suggested by racerone !!

 

[wrmdunker]

Well I had to wait for the neighbor to get a few minutes.....

Spark won’t jump the 5/16 gap nor any gap for that matter. I did test the plug against the block and got spark at the plug.

Motor fires momentarily with ether in the cylinders.

pulled the carb bowl drain plug and it was a bit milky. He didn’t empty any fuel or run it out last winter.

so so time to rehab the ignition? Then the carb?

 

[Crosbyman]

I would do the carb first and try it out first and if still acting up no arm in redoing the electricals on a "49 year oldy" (assuming coils were never replaced…. if yes start with points condensers and timing… visit utube for timing



http://www.youtube.com/watch?v=ga1Cjymj6ms&feature=youtu.be

take the stop switch apart and polish the innards… reassemble and reconnect everything

 

[wrmdunker]

Crosbyman....based on his lack of draining the carb and never using any stabilizer I tend to agree with the carb. Thanks for all the Utube links. Very helpful.

Im still puzzled re my spark tester though and why I couldn’t get a spark even at minimal gap. I even videoed the cranking and played back by frame in case I was missing it......

 

[wrmdunker]

Yes I agree that is lack of attention to fuel is a problem.

Btw his compression was 67 in both cylinders.

Still cant understand why I didn’t get a spark on my tester even at almost no gap. I even videoed the cranking to see if I was missing it.

 

[Crosbyman]

absence of sparks is either bad coils cracked so much that the HV jumps internally to frame ground

or… points are dirty… polish them a bit or at the very least wipe them clean with carb cleaner and a business card

plug wires maybe corroded inside at the booth spring clips .. they sometimes can be rejuvinated by clipping .5 inch back and resetting the pin dead centered on the wire

first things first take a volt ohm meter and see if you can read the secondary coils at 4-7 kohms between boot clips and frame ground

if you see 0PEN... INFINITY bad coil or bad wire or bad clip connection in the boot

there are lots of utubes on servicing OMC magnetos just do searches

Compression at 67 is ok 9.5hp as per Leroys generally are low on PSI and work fine …. all of mine have ...

 

[racerone]

A good magneto can build up to 25,000 volts.-----Jumps a gap of 5/16" with a " snap , snap " you can hear-----So this magneto needs attention !!