Re: Probs with fuel pump & RPM relay

[knut.s.grimsrud@xxxx]

I think the problem stems from a little misunderstanding of the 
operation of the RPM relay.

The RPM relay receives an impulse from the coil (I suspect it's 
the same signal driving the tach) that essentially informs it that the 
engine is running. After the relay no longer sees any impulses, it 
will shut off after a couple seconds in order to avoid running when 
the engine is stopped. Although it is true that the relay will shut 
off after a couple seconds, I don't think it's supposed to turn on 
first unless presented with an impuse on its sense signal (first 
spark when cranking).

The RPM relay is actually pretty simple and it's based on a 
run-o-the-mill 555 timer circuit (you can still get 555 timers at 
Radio Shack even though they really only sell cell phones and 
remote-controlled cars nowadays).

Knut



--- In dmcnews@xxxx, at88mph@xxxx wrote:

> I'm not getting power to my fuel pump when I turn the key to the 
'run'
> position. (when the pump should run for two to three seconds and 
then shut
> off ) I know that my RPM relay is fine. I tested it in another 
DeLorean
> and it does work.