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Erratic spark on 100hp johnson

chrono4

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"I just aquired a new to me bo

"I just aquired a new to me boat, a 1969 17' Glasspar, with a 100 hp Johnson on it.
Upon trying to get it to start, I pulled a plug and checked for spark. I only get 1 or 2 nice hot sparks, and then nothing. If I let it sit for a minute and try again, I get the 2 hot sparks again. Any insight on this issue? I searched, but didn't seem to find anything.
Thanks, Andrew"
 
"first back to basics....1.cor

"first back to basics....1.correct plug for motor??, 2.correct gap/setting??"
 
What year / model is the motor

What year / model is the motor.It may have points and distributor cap / rotor that need attention!!!
 
"It's model 100esl71a. N

"It's model 100esl71a. Not sure on year, early 70's it looks. It has a weird plug that has no ground electrode in it."
 
"sounds like a plug problem it

"sounds like a plug problem its self. I had plugs in my racecar that would do that. Once the porcelain heated up they wouldn't fire due to small fractures from high vibration. I know that this is a racecar and not a marine application that I'm referring to, however, the same materals are used in both applications when it comes to making the plugs. Get a new set of the plugs just like what you have in it. Then start with checking your plug wires, and grounds."
 
"Start with pulling the flywhe

"Start with pulling the flywheel and cleaning everything in there!!!!! Points ( gap to 0,010" ) , rotor, distributor cap, and likely replace the anti reversing spring.Sparkplug is not wierd, but rarely installed today. Best go with L77J4C"
 
go with the UL-77V plugs like

go with the UL-77V plugs like what you have in it..... The cost atleast $1 more for each plug but it will respond better to it!!
 
"Paul, how many motors do you

"Paul, how many motors do you own / have you repaired in the last say 40 years ????????"
 
"I'm sorry london marine i

"I'm sorry london marine if you feel that I've stepped on your toes.......however, I have specific experience with my evinrude that the OEM plug works better than the plug you are suggesting! I don't care if you've fixed 100 motors in the past 40 years.....if the UL-77V was originally supposed to be in that motor, than you should replace that plug with the OEM plug. This isn't a contest on who's better than who!!!! Quit being a visitor and sign in if you want to discuss experience with me.....better yet, prove yourself with being able to swallow your pride a little when someone responds to a response you have posted.....give a little and take a little. Don't let this raise your blood pressure to unhealthy limits!!!"
 
"Andrew.... Model number 100ES

"Andrew.... Model number 100ESL71A is a 1971 100hp Johnson. I prefer either the Champion QL77JC4 or L77JC4 spark plugs. On that model, gap the plugs to .030.

Set the ignition points as follows:

(Point Setting Of Battery Capacitance Discharge
( Ignition Models - 1968 thru 1972)
(Some have points - Some do not)
(Joe Reeves)

The points must be set to .010 but no wider than .010..... BUT in some instances due to a possible slight inaccurately machined crankshaft lobe or a slight offset of one set of points, a setting slightly less than .010 would be required as follows.

Whether the crankshaft has two or three lobes, when setting the points, check the setting of the points on each individual lobe by rotating the crankshaft by hand.

You may find that setting one set of points to .010 on one lobe, then turning the crankshaft to the next lobe, the gap measures .011 or .012 (too wide). This is where you would need to close that gap down to the required .010. A gap too wide can result in a ignition miss when throttle is applied.

Bottom line, pertaining to the point setting at the various lobe locations____ .010, .010, .009, is okay____ .010, .010, .011 is not!

NOTE.... The flywheel nut mustabsolutely be torqued to 105 foot pounds. Anything less will result in a sheared flywheel key.

Be aware of the starter cranking problem (time limit). Cranking the engine steady for any period exceeding 20 seconds could (and usually does) result in armature damage (throwing solder!).

A ignition problem that exists with the older Battery Capacitance Ignition systems (yours) is as follows with the cure.

(Voltage Drop To Battery Capacitance Discharge)
( Pulsepack When Electric Starter Is Engaged)
(J. Reeves)

On the older Battery Capacitance Discharge ignition systems (1968-1972), the electric starter reaches a point, even with a top notch battery, whereas the starter will draw excess voltage/current/whatever which results in a voltage drop to the pulsepack. The cure is to purchase a diode which is capable of handling 12 volts and installing it between the starter terminal of the starter solenoid (NOT the battery cable terminal) and the wiring terminal that supplies voltage to the pulsepack.

The diode must be installed so that the current flows from the starter terminal of the solenoid to the pulsepack... NOT vice versa. When that diode is installed in this manner, when the key is turned to the start position, the voltage that is applied to the starter is also applied directly to the pulsepack via the diode effectively eliminating the voltage drop and energizing the pulsepack with the required voltage needed for its proper operation.

When time permits, visit my store (copy/paste) at: http://stores.ebay.com/Evinrude-Johnson-Outboard-Parts-etc?refid=store

And to check the pulsepack itself, the following may be of some interest.

(Battery Capacitance Dischage Powerpack Test)
Various OMC Engines - 1968 to 1972)
(J. Reeves)

Purchase a small 12v bulb at your local automotive parts store (the 12v bulb is to look like a flashlight bulb, not a headlight bulb). Solder two wires to that bulb, one to the side of the bulb (ground), and the other to the positive point. You might use a bulb of a somewhat lower voltage to obtain a brighter glow... just a suggestion.

Remove the spark plugs. With the key in the on position, make sure that you have 12v going to the pack at the terminal block (purple wire). Now, connect the ground wire from the bulb to any powerhead ground. Connect the wire from the positive point of that bulb to the powerpack wire that is connected to the coil wire on the terminal board (blue wire).

Crank the engine and observe that bulb closely (CLOSELY!). If that bulb glows even the slightest bit, the powerpack is okay. It may be a very dim glow... just so it glows! If it doesn't glow, the pack has failed.

Keep in mind, that type powerpack (Battery Capacitance Discharge) demands a top notch battery of at least 70 amp hours. Any less will, in time, cause powerpack failure.

When time permits, visit my store (copy/paste) at: http://stores.ebay.com/Evinrude-Johnson-Outboard-Parts-etc?refid=store

Let us know what you find."
 
"Well, I was out the tinkering

"Well, I was out the tinkering with it and did get it to spark consistently. There was a corroded lead going from the brain box to up under the flywheel. Cleaned it up and have spark now.
Now, on to other issues. I cranked it a bit with the fuel line in a gas can, but never got any fuel up to the cylinders. Is there a way to help prime the system or what? I'm sure the carbs need cleaned, I just want to get it to pop and sputter at least. Thanks for all the helpful info."
 
"you will need a primer bulb t

"you will need a primer bulb to get good fuel pressure up to the carbs to begin with.....this allows the fuel pump that is driven off of vacuum to supply the fuel when needed. If you don't have a primer bulb in the fuel line, the vacuum pump can't pull the fuel by itself. They are fairly cheap and can be purchased at Wal-Mart."
 
try putting the fuel tank abov

try putting the fuel tank above the carb for gravity feed purposes if you don't have the primer bulb......fill the fuel line from the carbs up to the tank and then put the fuel line into the gas can....just a temporary fix to see if it "pops"
 
one more suggestion is to spra

one more suggestion is to spray some premixed fuel into each carburetor as no fuel in the carb means no fuel in the cylinder resulting in a combusting NON LUBRICATED cylinder!!
 
"There is a primer, but I'

"There is a primer, but I'm not using it. I just have a 2 foot piece of line going from the hookup on the motor to a 1 gallon can."
 
you should be running a 50:1 m

you should be running a 50:1 mix about 1 pint per 6 gallons of 87 octane fuel......TC-W oil. Two-Cycle Water Cooled Marine Oil...Chainsaw won't work!!!!
 
"Its not like I was going to t

"Its not like I was going to take it out on this fuel, I was just trying to get it to fire. Its 42 to 1, so its not very far off. I'll get the right fuel and try again soon. Thanks.s"
 
Not trying to come across as &

Not trying to come across as "brash" but you can ruin an engine quick that is 2 cycle that isn't mixed properly with the right oil and such....you know that! Just wanted to make sure so that if others were reading this post that had the same questions as you they would get the information in case they didn't know. Hope all is working for you.

Paul
 
Thanks for the info. I'll

Thanks for the info. I'll be sure to let you know what I find today. Any idea on what I should be paying for a manual for this engine?
 
"What does it usually cost to

"What does it usually cost to drop a set of bearings and a full gasket and seal set in a motor like this? After some closer inspection, it has a pretty bad what sounds like a rod knock to it."
 
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