Re: 1985 XP150 check valve
You are referring to the 6 check valves in the intake manifold. One per cyl. These are part of the recirculation system on later crossflows. It is designed to draw excess fuel from behind the reed valves when the engine is idling. Perhaps to prevent an idling engine from loading up. They are one way valves. 392988 and with age, may not work at all. About $ 20 each. Your engine will run fine without them, as older engines did not have them-but you may want to spend some time to get that system operational for better idling. You will want to make sure that if these valves work, that the hoses to them are intact (not leaking.) Found on V4 and V6 engines.