1985 VF500F ReBuild

Then that is not right. If the relay is in place and everything is properly connected and in working order, the relay only allows the pump to operate if the bike is being cranked or running. When you release the starter button and the engine is not cranking, the pump should stop, as it should not be getting power thru the relay.

 

Darn, that's too bad. Is it the relay then? I replaced the one on my VF700 before I sold it, but symptoms were different.
Out of curiosity, are the fuel pumps for the 500 and 700/750 the same?

 

That would be a very uncommon symptom of a bad fuel cut relay, but anything is possible I suppose.

No, the pumps are VERY different in their configuration and mounting. But their operation and pressure are the same.

Replacing a very old fuel pump with another just as old fuel pump...?

 

Get a used Mitsubishi pump and replace the relay with a quality toggle. That way you can work on the bike (like the fuel system) and not have it energize if the key is turned on.

You can always get a new relay and wire them (the relay and toggle) in parallel like I do on every bike. Then you can prime the fuel system after winter storage (draining the carbs) and not have to CRANK and CRANK to fill them back up. And you can get home WHEN the relay fails out in the middle of nowhere. Has saved my ass TWICE, once in the middle of a floating bridge.