Johnson 40e 74s blowing fuses

[piechka20018]

So I had my motor running fine with no issue. It then blew the 20 amp short fuse. I replaced it, as well as the starter solenoid, but the issue did not stop. I purchased the motor from someone else who recently reinstalled coils and set points. Does anyone else have this issue? Or does anyone else have a picture of a wiring diagram? I cannot find one anywhere. Thanks in advance

 

[Crosbyman]

in most... wiring layouts the fused B+ of the selenoid fat 12V post goes to the B terminal connection terminal on the starter key via side multi-wire harness.

a) if so equipped , try just openning up the main side harness plug to see if the fuse stops blowing on its own without the wiring from the front side of the boat

b) if OK disconnect the B terminal on the key and reconnect the side harness and if the fuse blows something is wrong in the harness . (shorted wires)

c) If OK next, reconnect the B terminal 12v wire on the key and if the fuse does not blow with the side harness connected, ... turn the key to ON if fuse blows possible bad accessories disconnect the A terminal and retry with a new fuse. if OK track down bad /shorted to ground accessory

d) if fuse blows on START...only possible shorted to ground selenoid control wire going back to the engine via the side harness

e) last but not least possible bad key innards

 

[oldboat1]

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[piechka20018]

in most... wiring layouts the fused B+ of the selenoid fat 12V post goes to the B terminal connection terminal on the starter key via side multi-wire harness.

a) if so equipped , try just openning up the main side harness plug to see if the fuse stops blowing on its own without the wiring from the front side of the boat

b) if OK disconnect the B terminal on the key and reconnect the side harness and if the fuse blows something is wrong in the harness . (shorted wires)

c) If OK next, reconnect the B terminal 12v wire on the key and if the fuse does not blow with the side harness connected, ... turn the key to ON if fuse blows possible bad accessories disconnect the A terminal and retry with a new fuse. if OK track down bad /shorted to ground accessory

d) if fuse blows on START...only possible shorted to ground selenoid control wire going back to the engine via the side harness

e) last but not least possible bad key innards

I was able to diagnose that it is the blue coil wire with white stripe that was causing the problem. There is a dead short when even when the wiring harness for that coil wire is disconnected near the coil. Don’t know where to go from here. Here Is my current wiring layout on my key switch. Any advice? Also, only 1 wire is connected on my neutral safety switch, is that an issue?

 

[racerone]

I believe that is the wrong switch for your motor !-----The battery is not used to make spark for the sparkplugs on this motor.----And yes there is only one wire on the neutral switch.-----Stop ----Get the correct wiring diagram before you damage the coils etc !!

 

[piechka20018]

Does anyone have a wiring diagram? I have been searching for days and for a similar one from evinrude and cannot find anything

 

[hardwater fisherman]

This is from my 1976 40hp service manual. Same ignition.

 

[Crosbyman]

strange that it ran with that switch .. in any event you must now track down the source of the low resistance to ground which is causing the fuse to blow .

the fuse has a B+12v side ... the other being the load side.

connect one VOM lead to the LOAD side of the fuse and the other to the engine frame and you will likely see very few ohms.. maybe 0 ohms (aka a short to ground)

progressively disconnect wires ...starting at the switch B+ if you still 0 ohms that power wire is touching metal ...find it.

if you see open great ! reconnect the wire to BAT and do same (disconnect) with other wires till the ground (0 ohms) goes away on the VOM. track down the ground on that specific wire.