"It is possible to rebuild a V
"It is possible to rebuild a VRO pump. I'm not sure what you mean by a palses unit. Pulse limiter possibly?
Sounds like a lot of money for something that "may be" the problem. If I were you, I'd make sure all the fuel line connections are tight and the hose is in good condition. The fitting on the fuel tank often has an anti siphon valve built in. These are notorious for plugging up. Also check for blockages on the fuel pickup inside the tank, as well as the fuel filter on the engine.
All this assumes your motor is having fuel starvation issues. That would be the usual reason for rebuilding the fuel side of the VRO"