[Diy_efi] '7747 trouble code list

[Shannen Durphey]

The fuel pump relay is energized whenever the ecm recieves reference
pulses.  It's closed when the engine starts and when it runs.  The oil
pressure switch can be completely removed and the engine will run as if it
were in place.

Try it and see.  In fact, the schematic on the ftp site may show the
wiring.

Shannen

Ne14RoxCJ at aol.com wrote:

> The ECM will use the Fuel Pump Relay for pre-start pressurization (a few
> seconds) and during cranking. After the engine starts, and builds oil
> pressure the pump is powered through the pressure switch. I suppose
> eliminating these components and powering the pump with a "hot in run"
> curcuit would work, but the pump will run ANY time the key is on. Also, the
> OP switch prevents the engine from running with less than ~5psi. I consider
> it "cheap insurance" for my $$ engine.
> 
> With any setup, the ECM needs to see the voltage going to the fuel pump at
> pin B2. A code 54 will set if the ECM sees less than  2 volts for 1.5 sec
> since the last reference pulse was received. HTH...
> 
> Beau
> 
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