Merc 4.3/alpha won't crank over

Z

zekester

Member
Jul 25, 2009
74
Lake Huron
Boat Info
1987 Donzi Hornet3
1990 Searay EC310 twin 7.4 inboards
Engines
330 TRS, 7.4 merc inboards
'94 290 DA twin 4.3, alpha drives, the key goes to on, horn sounds, key to start, nothing, no click, no crank, nothing. I thought neutral safety switch in the throttle control, jumpered it by connecting the two red/yellow wires, still nothing. I switched the two ignition switches, it's not that.

Shift interruptor? any other ideas? second engine starts no problem, so not a battery issue...

Any advice would be greatly appreciated...
 
Should be a 50amp breaker on engine - make sure it isn't tripped.
Check for power to the coil (purple wire from ignition) - from safety kill switch.
Check for power at the slave soleniod (from neutral safety switch - yellow/read wire).
If you are seeing power at these points, try jumping the slave solenoid.

You either don't have power at one of these points or the slave solenoid is bad and you just don't hear the click.

Here is a basic wiring diagram
https://www.google.com/search?q=ign...QIHaTDBjkQ9QEwAXoECAgQCQ#imgrc=i-kbwUB02PoJpM:
 
I'll check those things tonite,

more points to note, that engine stalled when docking and was hard to start but did start after lots of wiggling of throttle shifter, whether the wiggling did anything or not is unknown, that's why I thought neutral safety switch, then on docking again later in the day, it stalled and hasn't turned over or ran since...
 
Did it stall while shifting? If so then it could be the shift interrupt switch. They don't usually go bad, but get out of adjustment from stretching in the lower shift cable.
 
There should also be a 15A mini-blade fuse near the back top of the engine behind the distributor a few inches away from the large black plug that houses your ignition wires.
 
Excellent work gents, it was the slave solenoid, I ended up switching them to confirm, and that's it, thanks for pointing me in the right direction:)
 
zekester said:
Excellent work gents, it was the slave solenoid, I ended up switching them to confirm, and that's it, thanks for pointing me in the right direction:)
Click to expand...

Might be a good idea to replace both. If one just crapped out, the other might not be far behind.
 
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