1977 Johnson 140 HP Firing Issues

Wide_N

Petty Officer 2nd Class
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Jul 14, 2015
Messages
133
I have a 1977 Johnson 140 HP. It has been setting up for a long time. I am getting spark on only one cylinder. I have tested the stator output and it is good. I am only getting .3 volts or so on the sensor checks between white/black and black/white. The ohms check on the wires was a little over 10 on each. Am I looking at the timer base or could it be the power pack? Thanks in advance.
 

1983 ercoa 21'

Chief Petty Officer
Joined
Jan 12, 2014
Messages
632
What all test have you done?

have you started the motor?

have you cleaned the carbs ?

compression test?
 

1983 ercoa 21'

Chief Petty Officer
Joined
Jan 12, 2014
Messages
632
Any time you are being a motor back to life after sitting for a while these following steps should be taken.

disconnect any fuel supply.
remove spark plugs squirt two stroke oil in each cylinder and in the throat of the carbs torn motor over by hand to lube everything up .

then hook battery up and turn motor over.
do a compression test if it passes then test spark.
if it doesn't jump a 7/16 gap find out why by going to cdi website and testing the components.

if it has good spark move on to the fuel system by cleaning tank or tanks .
inspect fuel lines or replace them.

remove and clean carbs. And always remove jets and use carb cleaner making sure it comes out of the passage as it would come out of the straw.

replace thermostats and impeller/ water pump

I'll also add before turning the motor over always make sure a wasp or spiders,mice haven't made a home in the air intake system as this would be like taking a handful of dirt and throwing in the motor.
 

emdsapmgr

Supreme Mariner
Joined
Dec 9, 2005
Messages
11,551
The troubleshooting guide or the DVA guide from this website: cdielectronics.com is an expert site for cranking voltage outputs for your 1977 engine. These cranking voltage outputs are a great measuring tool. The factory did not start using them til around the early to mid 80's. You said you have been testing your stator and timer base. This website indicates that the cranking voltage outputs from the stator must be between 150 and 400 volts. As measured by a special "peak reading" voltmeter. Anything less than 150 volts cranking and the stator is condemned. The timer base must output 0.6 volts or it is condemned. Once you qualify both the stator and the timer base, the next most likely suspect is the power pack. The spark plug coils are generally reliable, and it's unlikely the other 3 coils have all failed at once.
 

Wide_N

Petty Officer 2nd Class
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Jul 14, 2015
Messages
133
I have done the compression check and it was 107 to 110 on each cylinder. The stator tested good with a DVA. I guess the next step is to replace the timer base because I was only getting .3 volts to it. Then the power pack would be the next suspect?
 

emdsapmgr

Supreme Mariner
Joined
Dec 9, 2005
Messages
11,551
When new, that engine probably had over 130+ lbs compression. If you get it to run now, it will be down on hp, based on the current compression #'s.
 

Wide_N

Petty Officer 2nd Class
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Jul 14, 2015
Messages
133
How do you test the power pack if you are not getting .5 volts from the timer base?
 

racerone

Supreme Mariner
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Dec 28, 2013
Messages
36,033
Inspect / test the starter motor.----Very easy to do and cost no $$ to do so.
 

Wide_N

Petty Officer 2nd Class
Joined
Jul 14, 2015
Messages
133
Ok I am confused. Starter is working fine. What would that have to do with getting .3 volts from the trigger?
 

Bosunsmate

Admiral
Joined
Apr 7, 2012
Messages
6,129
Dunno about the starter thing but your test of the sensor- should it be too ground instead of between the wires?
Also have you check none have continuity to ground? Often the turning of the timing base moves those wire necklace along the top of the crankcase and they chaff and then short out on the metal case
 
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