Logo
FULL SITE MENU

1980 Johnson 100 Trouble Shooting Help

C

cdods

New member
Hi,

I've got a 1980 Johnson (V4 Crossflow) that isn't running well. Over the next few days I'm going to be troubleshooting it and am hoping to use this discussion to get some questions answered as I go.

[FONT=Arial, Helvetica, sans-serif]Symptoms are one bank intermittently not firing. Additionally it won't idle. I have cleaned and rebuilt the carbs, the problems appear to be ignition related.[/FONT]

A couple of questions. And a few results from last night's trouble shooting. (I didn't get a chance to start the boat last night, so tests that require it running will have to wait for tonight.

Question 1: I only get about 250 RPMs when cranking. Is that enough to check for spark & measure stator voltages & compression, or do I need to get it above 300 RPM?

Question 2: The rectifier is definitely bad. Is it safe to replace the rectifier before figuring out what else is wrong, or do I risk damaging the new rectifier if I don't replace all the bad parts at once.

Question 3: I have weak spark on both cylinders on the right bank ((spark will jump about 3/16 gap with some "misses"), none on the left. Out of curiosity I checked the coil resistances (Primary to Ground). The bottom coils on both sides measure about 270 Ohms. However the top coil on the working bank showed an open circuit when I tried to measure resistance (Interestingly, this coil has been replaced at some point, all the other coils appear to be original). Resistance on the top coil on the non-working bank was about 2000 Ohms. Given those open / high measurements would you assume coils are bad (even though I get a spark from the one that shows as open)?

Question 4: For measuring voltages from the stator and timer. I have back probes I can use to try to probe into the connector, or piercing probes. What works best?

All advice appreciated.
 
Some will argue-----First thing I would do load test the battery , often a free service.------Then take the starter apart for inspection and testing.---- NO MONEY SPENT so far.
 
racerone said:
Some will argue-----First thing I would do load test the battery , often a free service.------Then take the starter apart for inspection and testing.---- NO MONEY SPENT so far.
Click to expand...

In agreement with racerone. It is a necessity that the engine crank over at least 300 rpms with the spark plugs removed.

IN addition, carefully, visually inspect the stator to see if it might be encountering a meltdown problem. If a sticky looking substance is dripping down from the stator onto the powerhead area... it will require replacing.

Let us know what you find.
 
I am probably in the wrong place but I have a 1964 Johnson 9.5 outboard motor and the water tube that goes up from the water pump has come out of the inner jacket is there a particular way to reinsert that to ensure that it's actually up into the grommet and I cannot see The Grommet by looking up through the holes but the drive shaft or the water tube goes up through I sure could use some suggestions thank you
 
racerone said:
Some will argue-----First thing I would do load test the battery , often a free service.------Then take the starter apart for inspection and testing.---- NO MONEY SPENT so far.
Click to expand...


Thanks,

Just so I understand. Will a weak battery result in a poor spark / no spark or is it simply needed to get the 300 rpm for testing?
 
The 12 volt battery is not used to make the spark !!!!------The battery / starter / cables must be in good condition to spin the flywheel rapidly.----That is what generates the spark on this motor.-----It seems to be difficult for some to grasp the concept .----In fact the motor will start / run with a totally dead battery if pulled over with a rope.
 
Last edited:
Yes... In total agreement with racerone's post/reply #6.

A top notch battery is needed to have the flywheel magnets speeding past two coils that are within the stator that generate the needed AC voltage to the powerpack capacitor to supply the proper spark.

If using a poor battery, you would normally have a slow cranking engine.... and that slow cranking engine would result in a voltage drop to the powerpack capacitor.... and that, in turn, would result in weak, erratic, or no spark.
 
First, Thanks for the answers so far.

I did a bit more testing last night (between supper and the mosquitos taking over). My homemade DVA adapter seems to have died, so I wasn't able to get voltage readings, but I did test the resistance values. I've ordered a DVA adapter.

I jumped the battery with my car to get good cranking. Boat battery is definitely weak, but I'm hesitant to spend any money until I know how much it is going to be required to get the boat up and working.

Note that the rectifier is also shot. If that would be impacting any of my testing, please let me know.

Stator - I get 300 Ohms between the two wires. Same value on both sides. CDI guide says it should be 450 Ohms. I get an open circuit between any of the wires and ground. Looking under the flywheel I see a 2 or 3 drips about the size of a rain drop of something that looks like tar running down what I think is the outside of the timer base. Is that the "goo" that should concern me?

Timing Base: Left side I get 35 Ohms between white and green (correct value based on CDI). Between white and blue on the Left Side, and between White-Green and White-Blue on the right side I get many MOhms or an open circuit depending on how I hold the wires.

So based on the resistance measurements, it would look like both the Stator and Timing Base are bad. However...

I get a good solid blue spark jumping a 7/16 open air gap on both the left bank cylinders.
No spark on the right bank cylinders.

The other oddity is that even on the right bank cylinders, if I connect my inductive pickup to read RPMs off the right bank spark plug wires (with the air gap tester connected) my meter is reading RPMs, though, the value seems very high (800 RPM).


Tonight I'm going to swap the power packs from side to side to see if that changes anything. Assuming the "no spark" doesn't follow the power pack, do I have enough information to conclude that at least the timer base is bad, or would you wait to actually measure voltages?

And a couple other questions just to help me learn, understand & improve my troubleshoot skills?

1) The green and blue wires from the timing base. I assume green is the "timing signal" for one cylinder, and blue for the other? If so, do you happen to know which is which?

2) Given the resistance between the white-blue pair on the left side is is completely out of range, how can I still be seeing a good spark on both cylinders on that side?

3) Given the inductive pickup is seeing something on the right side even though I don't get a spark. Would connecting a timing light to those wires to see if the timing of what's happening on those wires is consistent tell me anything?

4) On one of the spark plug (on the left bank), I get an open circuit, or very high (MOhms) resistance across the wire, depending on how I hold it, yet I get a good spark on that cylinder. My assumption is that the wire is bad, but just good enough to still carry enough current for a spark in the relatively ideal conditions of an open air spark tester? Is that a fair assumption?

Again, thanks, I really appreciate the help as I try to get this figured out.
 
You state: "Stator - I get 300 Ohms between the two wires. Same value on both sides. CDI guide says it should be 450 Ohms. I get an open circuit between any of the wires and ground. Looking under the flywheel I see a 2 or 3 drips about the size of a rain drop of something that looks like tar running down what I think is the outside of the timer base. Is that the "goo" that should concern me?

If that "goo" is dripping out of the present stator, yes you should be concerned and it should be replaced... BUT... it is always possible that it had dripped from a previous stator and your present one is okay... Double check to be sure!

You state: "Timing Base: Left side I get 35 Ohms between white and green (correct value based on CDI). Between white and blue on the Left Side, and between White-Green and White-Blue on the right side I get many MOhms or an open circuit depending on how I hold the wires.

I don't know how the above readings could be possible if you are indeed having good spark on "Both" cylinders of the port/left bank. However the readings of the starboard/right side sensor readings indicate the sensor is bad.

A break in the wire(s) would have a meter jump around, depending on (as you say) how you hold the wires.

BTW... The color "blue" always indicates "Top".
 
Back
Top