I am attempting to create a very basic circuit to automatically control the fuel system changeover on a vehicle. Essentially, I am trying to start two timers once the ignition is shut off in order to delay the actual engine shut off. In other words, once ignition is off pump 1 runs for another 2 seconds and pump 3 runs for an additional 60 seconds.

Currently I am attempting to hook up two 555 timers but I am not sure if I am understanding the theory correctly. My idea was to hook up the ignition to pin 6 in order to start the timer once voltage was removed and have the output turn on a relay to the appropriate pump for the duration. However, it has come to my attention that the input signal needs to be shorter duration than the output? Does this mean I am unable to use a 555 for this project?

 

See Bill Marsdens blog on 555 timers.

 

sorry, but car mods are off-limits here for legal reasons

 

Hello,

I am closing this thread as it violates AAC policy and/or safety issues.

Quote:
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Bertus