[T3] 71 Squareback MT/FI - Intermittent Engine Stopping

[Wisconsin Spryers]

Update on the latest:

Given the likelihood that my intermittent problem is caused by a poor
contact/connection problem and not an ECU issue, per Jim Adney's suggestion
I've cleaned the relay contacts on both the Fuel Pump Relay and Main Power
Supply Relay. In addition, I've made sure all power and ground contacts
related to each of the relays are solid and in good condition.

I used a heavy duty piece of white copy paper and ran it between the
contact points while applying pressure on the contacts. On both relays
there was a black smudge on the paper on the 1st "cleaning".  The Fuel Pump
Relay appeared to be dirtier - heavier, darker smudge. I repeated this
process until there were no more indications of soot left on the paper.

In an attempt to identify which relay is suspect, if I have any future
issues, I've installed little 12-volt monitoring lights, one for each
relay. For the Fuel Pump Relay, I have a monitoring light that is powered
off of terminal # 87, the terminal that is wired to the positive terminal
on the Fuel Pump. For the Main Power Supply Relay, I have a monitoring
light also powered by its terminal # 87 which is supplying power to both
the ECU and the Fuel Pump Relay. Both monitoring lights are grounded to the
body.

My rationale is that if the engine stops again, by viewing the monitoring
lights I'll have a better idea of where to focus on determining the source
of the problem: Both lights ON - something other than the relays; Main
Power Supply Relay Light OFF - faulty Main Power Supply Relay or some
faulty connection supplying its power or bad ground (Note: The Fuel Pump
Relay Light would also be OFF in this instance as it gets its power from
the Main Power Supply Relay as does the ECU). Fuel Pump Relay Light OFF &
Main Power Supply Relay Light ON - faulty Fuel Pump Relay or ground issue
between the relay and the ECU.

When I turn the ignition key to "ON", both monitoring lights are ON, but
then ~1 second later the Fuel Pump Monitoring Light goes OFF as expected.
When turning the key to "START", both lights are ON and remain ON while the
engine is running.

For the past couple of days, after tightening up all the power connections
and ground contacts, and cleaning the relay contacts, I have not had
another "engine stopping" occurrence during my short around-town trips.
Hopefully, a loose connection and/or dirty relay contacts was the issue.

-- Richard Spryer
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