Snakeriversailor77
Contributing Member
Working on a Mercury jet boat with Yamaha Optimax engine. The engine starts and runs great but then will just stall. Restarts and runs great again only to stall out. Previously had a fuel pump issue and replaced the internal high pressure pump in the VST and the tiny lift pump. The other low pressure pump was not replaced but tested ok and was pumping fuel. Hate to replace that pump too as they are pretty pricey. Is there another test I can do to the pump to test it? The engine has had all its filters replaced and the fuel is good. Im thinking perhaps the float in the VST is sticking closed and is not refilling with fresh fuel. But why is it refilling after the engine shuts down?