Engine startup Electrical Progression

[otgdy]

I have an 84 Wellcraft with a Merc 260 alpha 1 thunderbolt iv ignition.
Shifter is in neutral and the neutral the shift cutout switch is in the valley.

When you crank the engine where is the 12 volts coming from to the coil.
When I crank the engine it will not start until I release the key. Some autos have a second circuit to keep the coil hot during cranking. This boat does not appear to have have this circuit.

Got the engine running shift cutout switch is still in the valley. Shift either forward or reverse. As soon as the roller exits the valley there is no voltage to the coil. The engine dies. The cutout switch kills the coil when not in neutral. Where does the current come from when the switch is out of the valley ? I believe it grounds out the primary circuit. Could be wrong.

In a nutshell the engine will not start with the starter circuit engaged and will die when shifted out of neutral.

If you have a diagram that shows these circuits that would be great. If you could explain the above I would really appreciate it.

Thanks
OTG

 

[dubs283]

Re: Engine startup Electrical Progression

what is the voltage at the coil (+) while cranking??

a worn shift cable will cause the shift interrupt switch to engage when going into gear, i.e. not operate properly (the interrupt switch is for coming out of gear only)

here is a link to download an engine manual that will have a wiring diagram for the t-bolt 4 system:

http://www.4shared.com/document/LXsFg1do/Service_Manual_09.html

 

[otgdy]

Re: Engine startup Electrical Progression

what is the voltage at the coil (+) while cranking??

a worn shift cable will cause the shift interrupt switch to engage when going into gear, i.e. not operate properly (the interrupt switch is for coming out of gear only)

here is a link to download an engine manual that will have a wiring diagram for the t-bolt 4 system:

http://www.4shared.com/document/LXsFg1do/Service_Manual_09.html

Let me start with a quick thanks for responding so quickly. There is no voltage at the coil during actual cranking only when key is released to the ignition setting. The actual battery voltage is around 9v due to starter drain. To make sure I don't have is backwards... On the shift linkage there is a switch with a roller that runs on a two humped cam. When between the lobes there is current to the coil. When the cam is on the lobe the ignition is grounded out .. right ? keeping the engine from running in gear. Is this correct or is there something else in play ? As soon as I move the throttle / shifting into fwd/reverse the cam moves up on the lobe and current is interrupted and the engine shuts down.

Thanks
OTG

 

[Don S]

Re: Engine startup Electrical Progression

Let me start with a quick thanks for responding so quickly. There is no voltage at the coil during actual cranking only when key is released to the ignition setting.

Your ignition switch has failed.

A second option to installing a new switch is to install a wire between the D terminal of the starter (see picture below) and the + terminal of the coil. This is used in many of the electronic ignition systems to assure full cranking voltage to the coil during starting.

 

[otgdy]

Re: Engine startup Electrical Progression

Your ignition switch has failed.

A second option to installing a new switch is to install a wire between the D terminal of the starter (see picture below) and the + terminal of the coil. This is used in many of the electronic ignition systems to assure full cranking voltage to the coil during starting.

That worked. Thanks for the pic and jumper points.
OTG

 

[Bondo]

Re: Engine startup Electrical Progression

On the shift linkage there is a switch with a roller that runs on a two humped cam. When between the lobes there is current to the coil. When the cam is on the lobe the ignition is grounded out .. right ? keeping the engine from running in gear. Is this correct or is there something else in play ? As soon as I move the throttle / shifting into fwd/reverse the cam moves up on the lobe and current is interrupted and the engine shuts down.

Ayuh,.. Because the Lower Shift Cable is boogered up, It's activatin' the switch...
It shouldn't move, unless coming Out of gear, In the water....

The switch is Workin',... The Cable Ain't...

 

[otgdy]

Re: Engine startup Electrical Progression

Ayuh,.. Because the Lower Shift Cable is boogered up, It's activatin' the switch...
It shouldn't move, unless coming Out of gear, In the water....

The switch is Workin',... The Cable Ain't...

Oh you got that right. Did some checking into the lower shift cable and it seems that I
totally missed the slot that it is supposed to go in on the top part of the cable. See my other post if you haven't messed with this yet. Learned a lot. Hopefully this weekend I will be out on the Chesapeake.
Thanks again for all your help
OTG