i towed truck (90 ford f150 5.8 swapped to 4.9) after clutch bracket broke left the key on while i wait for parts bad mistak. been throwing parts at it chasing a no fire issue after fixing pedal bracket after replacing starter solenoid fuel pump an relays checked ecm was damaged replaced still no fire i was getting spark before i removed the ecm i would be grateful for any help

 

If you tell us what car you have we can give you an actual answer. But without any information it will draw more power than it would draw with the key in the off position. How much more, depends on many factors. With a brand new battery and the radio off and nothing in the cigarette plug the current draw is probably negligible. If you have a multimeter there's a simple measurement that will give us more information.