1972 125hp johnson lost the spark

[natedawg]

it was working fine yesterday shut it off let it sit overnight charged the batt. went out this morning and no spark. checked all connections all are good battery is fine fully charged...Im thinking that the cdi unit went on it but im not sure on how to be sure other than spending the 200 to 300 on a new one.......(i only payed 25 bucks for a 16 foot early 80s Glastron with a 72 johnson on it so im not into it too much its a nice boat and dosent need too much to get in the water)thanksNathan

[KYHunter2]

If it has a fuse under cowling, check it. Often, it will blow if your connections arent great. Or, if you peck around, hooking up charger. It'd be my first check. Do a proper spark test. Check the wiring, especially the connections. All wiring. The manual will walk you right through it. Or do a search for spark , loss of spark etc. Good-Luck, KYHunter KYHunter

[gatorred]

is there a kill switch,i seen bad point's if no point's control box go to or low battery on merc 80 left me rowing one day too.

[Joe Reeves]

(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.

[natedawg]

KY,I did check all the connections and there is a fuse under the cowl and its fine every thing seams to be good all the wiring is in order.Joe, I did do a test like that except i used a pin light tester and i didnt see anything at all coming out of the powerpack going to the coil...gatorred, there is no kill switch besides the key..Nathan

[natedawg]

well i went out there and clean up all conections, including the ignition switch, and everything inside the cowl and it now works.....yeppie!!! and i hope it keeps working too.

[KYHunter2]

Natedawg, congrats, glad to hear your motor is running again. On any exposed connections, ie: grounds to block , terminal connections etc. If you get a can of liquid tape , and coat them with it. You'll have alot less electrical problems from corrosion. Peels off easily , if need be. Keeps them good and dry. Good-Luck, KYHunter

[natedawg]

cool i will do that thanks for all the helpNathan