Johnson 175 power drop

[fisheromen]

1983 175hp Johnson. This problem only happens on the initial run from the ramp. Starts and runs fine. Head across the lake and suddenly one entire bank of cylinders drops and the boat falls off plane. It sits and sputters for a few seconds and then picks back up. This scenario may repeat 2-6 times. Then it runs like a champ the rest of the day.

Power pack has been suggested, but I want to rule out any less expensive causes. I have cleaned the plug-in connections.

 

[emdsapmgr]

Re: Johnson 175 power drop

It's not unusual to have ignition problems after warmup. The electronics on any engine tend to fail once the engine reaches it's normal operating temperature. Heat is the bane of weak electrical components. On a statistical basis, the power pack is usually the prime suspect on ignition problems. On your engine you have a couple of options. I'd take a timing light and a friend with you next time you go out. When the engine starts to miss, put the timing light on each of the 6 leads and see which bank (or wires) are not firing. Once you sense what is going on, you can swap the two power packs and see if the problem moves to the to the other head. This test procedure should indicate if it is a pack related failure. If it is just one wire, you can also swap single coils to check them. Double check for clean ground wires on the packs, coils. See where this takes you. The other components in the ignition system are the timer base and the stator.