Mercury 500efi no fuel pressure. Help lol
 

I have a 500efi that’s fed by an Aeromotive pump. I’ve check the pump separate from the efi system and it functions as it should. However when I turn on my ignition the pump doesn’t kick on now. What could cause this? What should I check? Thank you for your help. I’m lost on this and I don’t want to damage the ECU by accidentally shorting something

Could use a motor serial number

Start by checking fuses,there on top the motor
Use a voltmeter and see if the Main Power Relay (MPR) energizes when key turns ON

https://cimg6.ibsrv.net/gimg/www.off...038ac61517.jpg

The block is not original to the efi system. It has newer aluminum heads and a 525 cam. It’s a bit of a Frankenstein

OK, let us know what you find

Solved
 

It won’t let me post pics since I’m new, but it was definitely the fuses. The corrosion had destroyed them and the female pins in the dongle. It’s running great now. Thanks for all the advice