EFI332 Fuel Pump On/Off Algorithm

[Tom Cloud]

>> 
>> Does the EFI332 project plan on implementing an algorithm to 
>> control the fuel pump (relay)?  From what I understand about
>> OEM ecmm's, they turn off the fuel pump if the engine hasn't 
>> started for X seconds.  
>> 
>
>  There is a simple algorithm in the efi code on the web site
>  which checks for crank motion during the attempt to get synch.
>  If there has been no motion for x seconds (x a user input),
>  then the pump is turned off via a relay controlled by the
>  octal serial chip. When synch is achieved, the pump is turned
>  back on and stays on as long as there is synch. If the crank
>  were to stop, there would be loss of synch and the logic
>  would return to the 'get synch' loop and again cut off the pump if
>  no motion in x seconds. An alternate way of checking would be
>  to use a watchdog timer. As for the timeout, I believe Electromotive
>  uses 20 seconds. I don't know what the oems use - but FORD has
>  an inertia switch to kill the pump in the event of an accident;
>  since I have a **very** high flow pump, I intend to implement
>  this idea also.

the Holley ProJection uses pulses from the ignition -- if none
after something like 10 seconds, then the pump relay opens
(a retriggerable 555 or 74123 monostable will achieve this)
and some use the oil pressure switch -- loss of pressure
kills the pump (AND-ed with the ignition switch, so it'll
run while starting and then timing out and looking for oil
pressure).

Tom Cloud <cloud at peaches.ph.utexas.edu>