350 Mag Cutting Out

[clockwatcher]

1990 350 Mag/Alpha I. The engine will start and run for a while, then dies. Gauges stay on. It will start again immediately. Per Don S. in another post, I ran a wire from the + battery to the + coil and it runs perfect all day long. I installed a new coil and ignition sensor, plugs & wires, distributor cap and rotor. I replaced the engine to helm harness with a new one, no difference. I disconnected and jumped across the lanyard switch, no change. On the ignition switch, I jumpered from the Orange to the purple, no difference. Is that the correct way to test the switch?

Per the wiring diagram, it appears connection could be broken at the tach. Is that correct?

What should I try next?

 

[clockwatcher]

Re: 350 Mag Cutting Out

Forgot to add: the boat will shift forward and reverse and the shift interupt switch will kill the engine when I push on it.

 

[NHGuy]

Re: 350 Mag Cutting Out

"Per the wiring diagram", are you meaning the ignition diagnostic diagram? Whichever it is, continue to follow the diagnostic path by checking the tach wiring. That's what your testing result was, right?

 

[clockwatcher]

Re: 350 Mag Cutting Out

I have a diagram of the engine and another for the helm/gauges. I wish I had some sort of diagnostic diagram. It appears that purple (pin 5) creates the circuit from the ignition switch to the tach and then back to the coil. Should I run a new tests wire for the purple circuit from the coil to helm? I could start by connecting it to the switch and move to the tach. I'm not really sure what to do next.

 

[NHGuy]

Re: 350 Mag Cutting Out

Check your PM's I'm sending you a valuable thing.

 

[clockwatcher]

Re: 350 Mag Cutting Out

Thanks NHGuy. I'll try that from home. Big brother here at work is blocking it. Appreciate it.