Runs 20 minutes dies like clockworkWait 15 amp Go

" 1970 115 HP Evinrude: Change

" 1970 115 HP Evinrude: Changed coil,cleaned and readjusted carbs,checked connections. Runs ok for about 20 minutes then dies.Seems no spark then after about 10 to fifteen minutes it will start back up and run for about another 20 minutes but by then are back to launch and ready to leave..Any thoughts on what "posesses" this critter?? Maybe old age and it wants to retire?
This is a friends first and probably "soon to be last boat" if we dont get this figured out. Good thing he has a 5 hp fishing motor to! "

"Sounds like you may have an i

"Sounds like you may have an intermitent powerpack. You can check it out as follows. I do have one new pack left in my remaining stock that I will discount if yours proves to be faulty. [email protected]

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

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.

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.

Joe (30+ Years With OMC)"