[DML] Re: RPM and Lamba Relay Clicking
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[DML] Re: RPM and Lamba Relay Clicking

Just a clarification:

Normal operation of the RPM relay - 

On initial power-up (key on RUN, engine not running) the RPM relay 
will close, enabling the fuel pump. If you don't crank the engine, 
within about a second the relay will drop out and the pump will stop 
running. And the frequency valve will stop buzzing. 

With the engine cranking OR running, the RPM relay senses distributor
pulses (uses the same feed as the tachometer) and applies continuous power to the fuel pump. If the engine stops, within about a second the RPM relay will turn off the fuel pump. (That's what the NE555 timer chip in there is timing).

It should never be "fluxating" (is that a real word?) in normal 
operation. The fuel pump should be running and the frequency 
valve should be buzzing any time the engine is cranking or running. 

Dave S

--- In dmcnews@xxxxxxxxxxxxxxx, "David Teitelbaum" <jtrealty@...> 
> I assume you are referring to the RPM relay as far as pulses are
> concerened.The relay should not pulse. It receives pulses. If it
> doesn't receive them or if they are not often enough the relay is
> supposed to drop out and shut down the fuel pump. If it did pulse 
> fuel pump would start and stop. As for the Lambda relay it shouldn't
> pulse either or the frequency valve would stop buzzing when it did 
> under normal running conditions it should buzz all the time the 
> is running. IMHO the clicking that the owner is hearing may be one 
> the circuit breakers, most likely the cooling fan breaker. He says 
> frequency valve does not stop buzzing so he can't be hearing the
> Lambda relay clicking (assuming his wiring is stock of course). I 
> found the most and the worst modifacations are usually done to the
> wiring system of a used car. I can only offer advice based on a 
> configuration. Any mods and all bets are off.
> David Teitelbaum
> vin 10757
> --- In dmcnews@xxxxxxxxxxxxxxx, "John Hervey" <john@> wrote:
> >
> > David, wouldn't it be clicking on and off as the pulse is 
> from
> > the pulse coil.
> > John Hervey

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