[DML] Re: RMP Relay woes?

["Adam S." <AdmiralSenn@xxxxxxxx>]

The RPM relay runs the fuel pump as long as it gets ignition pulses, which I believe come from the distributor by way of the ignition computer (someone correct me if I'm wrong). Power for the fuel pump runs through the relay socket. 

When they go bad you can get the symptoms you describe, though there's always the possibility that the pump itself is flaky. If you want to test it, make a jumper from two male spade terminals and a length of wire and jumper the socket as shown here: http://specialtauto.com/delorean-parts/images/rpm-relay-jumper.jpg

(This is also a handy trick for diagnosing the fuel pump circuit without having to run the car.)

Be advised that the jumper WILL continue to run the pump even if the car is off, so make sure to remove it when you're done! I *think* (not 100% sure) that this will also disable the Lambda system since that also depends on the RPM relay, so you may have some weird fuel mixture changes until you replace the relay.

If you duplicate your failure conditions with the jumper in place and the problem doesn't reoccur, especially after multiple tests, then your relay is probably bad. 

If it IS bad, on DMCTalk there is a person named Dave, his handle is Bitsyncmaster. He sells an upgraded RPM relay (you'll need to send in yours as a core or pay a bit extra) made from solid state components. It's generally regarded as a superior product in just about every way. I think the price is $75 with your old relay. Buy one of those, it's the last RPM relay you'll ever need.

If the relay isn't bad... then 

-Adam S.

--- In dmcnews@xxxxxxxxxxxxxxx, "roller822" <roller822@...> wrote:
>

> 
> The next day I took another drive and the same thing happened: I found fuse 1 to be getting warm(rmp relay?). My question is this.  What exactly does the RPM relay do, and does it rest itself when it cools after about 10 mins of sitting, will this relay also take out the fuel pump briefly? or is there a circuit breaker that is giving me a hint that it is heading for the trash?
> 
> Thanks in advance for any info and help.
> 
> John Kennedy
> 11196
>




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