Starting Problem Question

[Ron Rosenfeld]

Friday AM I was unable to start my Mooney: 1965 M20E; Lycoming IO360A1A;
Slick Magnetos; Starter Vibrator; Bendix ignition/starter switch.

The engine would turn, and fuel would flow (actually dripped out onto the
ground after a while), but no sign of "fire".

Subsequent troubleshooting revealed that a wire from the condensor on the
starter magneto (I think it's the left) had its insulation worn through by
rubbing on a portion of the case internally and may have been shorting out.

During this troubleshooting process, it became apparent that we were not
hearing the noise of the starter vibrator (although I cannot be certain of
that being the case prior to the arrival of my IA).

After rerouting that wire so that it could not possible short out to the
case, the engine started normally, both on that day and a few days later.

My question: Is it possible for this possibly shorted condensor wire to
inhibit the starter vibrator from "vibrating"? If so how?

The POH only shows the connection to the ignition switch, and nothing about
the high voltage side of this unit.

My fear is that I may also be dealing with either an intermittent starter
vibrator, or an intermittently dysfunctional ignition switch.


Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA)

[[email protected]]

Ron Rosenfeld wrote:
snip

> My question: Is it possible for this possibly shorted condensor wire
to
> inhibit the starter vibrator from "vibrating"? If so how?
>
> The POH only shows the connection to the ignition switch, and nothing
about
> the high voltage side of this unit.
>
> My fear is that I may also be dealing with either an intermittent
starter
> vibrator, or an intermittently dysfunctional ignition switch.

The ignition vibrator is connected to both the switch(p-lead)lead and
the start/retard lead on the "starting" magneto and is only going to
operate when the main contacts AND the start/retard contacts in the
magneto are "open". The condensor is connected across the main
contacts. If the wire was shorted to the case, both contacts would be
connected to "ground" regardless if they were open or shut.

The ignition vibrator is only connected to the "low" side of the
magneto, and the pulsating voltage from the vibrator directed into the
low side of the coil induces the spark out of the "high" side.

Hope this helps;

TC

[Ron Rosenfeld]

On 8 Mar 2005 12:31:38 -0800, "
> wrote:

>
>Ron Rosenfeld wrote:
>snip
>
>> My question: Is it possible for this possibly shorted condensor wire
>to
>> inhibit the starter vibrator from "vibrating"? If so how?
>>
>> The POH only shows the connection to the ignition switch, and nothing
>about
>> the high voltage side of this unit.
>>
>> My fear is that I may also be dealing with either an intermittent
>starter
>> vibrator, or an intermittently dysfunctional ignition switch.
>
>The ignition vibrator is connected to both the switch(p-lead)lead and
>the start/retard lead on the "starting" magneto and is only going to
>operate when the main contacts AND the start/retard contacts in the
>magneto are "open". The condensor is connected across the main
>contacts. If the wire was shorted to the case, both contacts would be
>connected to "ground" regardless if they were open or shut.
>
>The ignition vibrator is only connected to the "low" side of the
>magneto, and the pulsating voltage from the vibrator directed into the
>low side of the coil induces the spark out of the "high" side.
>
>Hope this helps;
>
>TC

OK, it sounds as if I don't need to go looking for another problem (so long
as I have no more starting problems).

Thank you. It does help.


Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA)

[Ron Rosenfeld]

On 8 Mar 2005 12:31:38 -0800, "
> wrote:

>The ignition vibrator is connected to both the switch(p-lead)lead and
>the start/retard lead on the "starting" magneto and is only going to
>operate when the main contacts AND the start/retard contacts in the
>magneto are "open". The condensor is connected across the main
>contacts. If the wire was shorted to the case, both contacts would be
>connected to "ground" regardless if they were open or shut.
>
>The ignition vibrator is only connected to the "low" side of the
>magneto, and the pulsating voltage from the vibrator directed into the
>low side of the coil induces the spark out of the "high" side.

I gave you wrong information. It was not the lead from the condensor --
rather it was the primary lead from the coil (coil to points) that was
possibly shorted out.

How does that change your analysis?

Thank you.


Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA)

[[email protected]]

Ron Rosenfeld wrote:
snip

> I gave you wrong information. It was not the lead from the condensor
--
> rather it was the primary lead from the coil (coil to points) that
was
> possibly shorted out.
>
> How does that change your analysis?

No change. The vibrator voltage output would be grounded prior to
reaching the low side of the coil (as if the contacts were still
closed).

TC

[Ron Rosenfeld]

On 9 Mar 2005 09:48:15 -0800, "
> wrote:

>
>Ron Rosenfeld wrote:
>snip
>
>> I gave you wrong information. It was not the lead from the condensor

Thanks.
Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA)