I'm most familiar with the older diesels and know generally about gas
engines, but not specifically their various permutations and
combinations of parts so read this as general guidance rather than
specific repair instructions.

Suggest you create a new post specifically about the Over Voltage Relay
- what it does, exactly, and specifically how one can test it.

With respect to the cold start system, basically, there is an engine
temp. sensor, a time/temperature relay and an electric valve that sprays
fuel into the intake manifold. You engine may differ in its parts but
the idea is:

1. if the engine is below a specific temp. (I believe its about 20
degrees C.) then
2. power is sent to a time / temperature relay (or similar) which is ON
for a brief period, longer when colder.
3. The electric cold start valve sprays fuel into the intake for about 5
or 10 seconds - just long enough to get the motor running.

You've changed to usual ignition parts but not touched the cold start
system. Since you're good with a test light try the plug to the cold
start valve when the engine is cold and someone briefly cranks the
starter. There should be power to that plug, if only briefly.

I hope this helps you.

Tom

In the course of my "travels" on Usenet a kind soul posted this
explanation of the OVP relay. I don't know enough about electronics to
opine on its truth but you may.

The OVP relay protects the sensitive electronic circuits, i.e. your ECU
from high voltages.

It basically consists of a fuse, followed by a relay energized by a
small circuit, which has a zener diode built-in. This relay feeds the
the SRS, ECU and ABS (any others?). If the voltage goes too high, the
zener conducts, and shunts the circuit to ground, cutting out the relay,
and if very high, blows the fuse.

These relays get tired, as basically, it has to activate continuously
when the engine is running. 10 years ± is about the lifetime.

When it cuts out, your engine reverts to "dumb" mode, and won't
compensate for temp, O2, timing, etc.

SRS, ECU and ABS, that's all.  And depending on model and/or # of
systems that are protected, there are different versions of OVP relay,
between 5 - 9 pins, and 1 or 2 fuses.

A cross-cable during a jump start can easily kill this relay.

just check around the seams to see if it is leaking gas, if not you are very
likely OK

cheers