99 Yamaha 0X66 fuel injected 150 hp Trim issues

[panasonic]

Also after we installed the new relay, the trim worked fine after starting the motor a few times on the water. Then it didn’t

As already stated you have a bad connection, corroded or broke wire inside it's outer casing somewhere.

Whatever wiring you disturbed when you hooked up your pumps you need to go back and look at closely....I think you will find your problem there.