[DML] Re: Warm Start Issue (David McKeen)

["content22207" <brobertson@xxxxxxxxxxxx>]

As its name suggests, the cold start valve only operates on a cold
engine. There's a thermal switch in the cooling system (side of the
water pump if I remember correctly) that opens when the coolant heats
up, severing the cold start injector's ground and preventing it from
spraying. The hot wire to the cold start injector is live every time
the starter circuit is engaged -- only the ground is severed. I seem
to remember that the thermal switch has its own resistance heater as
well, to prevent over use of the cold start injector even on a cold
engine -- if you keep cranking the engine without starting, the cold
start valve will eventually stop spraying.

The CPR plug swap works anytime because its ground is always connected. 

You need rest pressure because DeLorean fuel injectors are mechanical.
They do not spray without a certain amount of fuel pressure. On a cold
engine, the cold start valve provides enough fuel for the engine to
start, the pump to run, primary pressure to build up, and the
mechanical injectors to start spraying. A warm engine will not use the
cold start valve. If the injectors can't spray because pressure is
missing (no rest pressure), no fuel will enter the engine. You can
crank it all day and it won't start like that. Remember: The pump does
not run and can not reprime the system until the engine is turning a
certain number of RPM's.

As Harold pointed out, the pump does run for a split second when the
car is first energized. You can re-energize the car several times to
build fuel system pressure (run the pump for several split seconds),
then start a warm engine that has rest pressure problems otherwise.

Bill Robertson
#5939

>--- In dmcnews@xxxxxxxxxxxxxxx, "bitsyncmater" <david.mckeen@...> wrote:
>
> My car starts great cold.  Is the cold start valve needed to start it
> cold.  If it was just used to start a warm engine than you may have
> discovered where the problem lies.  Bit then why does a longer rest
> pressure time also fix the problem.




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