Fuel pump won't shut off!!

Hello, I'm new to the forum and new to Supra boats. I wasn't wanting my first post to be an issue, but unfortunately it is☹️. I just purchased a 1994 Supra La Brisa. It's in very good shape. Has the PCM 5.8L HO. It ran great on the test drive. I got it home, about an hour drive and opened the engine cover and could hear something humming on the engine. After poking around found it was the high pressure fuel pump. I had to unhook the battery to get it to shut off. First question, anyone see or hear of this before? Second question, to troubleshoot, where are the relays on the boat. Was going to start there. Will try to upload picture of part that is running. Appreciate any and all help and thanks in advance.

If you have a volt meter check and see if the pump is getting voltage when the key is in the off position.

I would bet its the contacts are fused/stuck on the fuel pump relay. Sorry I can't help with the location. Have you tried tracing the wiring? Most times it goes into the main harness and is hard to follow. I would think there is some type of mounting plate on the rear of the engine that would have relays and the main circuit breaker.