Stock Petcock question

[Gary]

97 Valk, about 80k miles.

I had pulled the tank to do a K&N air filter clean and re-charge and decided to check the petcock while the tank was off for fuel flow with no vacuum. Sadly, it had flow in On, Reserve and some very limited in Off (off may have been remnants from the other positions.

I had a new Cover Set on hand so I just replaced that, put it back on the tank, tilted  the tank for some gas exposure and... it has flow in On and Reserve. I did take a look at the removed diaphragm's and could not detect any holes.

I should also mention I did also have to snug up the screws on the cover set a bit as it did appear to have some minimal leaking after the new install. That area doesn't appear to be leaking any more but it does seem to have flow, as mentioned in On & Reserve. 

So is this p-rooster shot?

I realize it is an OEM and that a Pingle is a preference for many. I just hate to lose that slight extra mileage from reserve... 

The complete petcock assembly was replaced just less than 30k miles ago.

I appreciate your feedback.

[Gryphon Rider]

If it's letting gas through without vacuum, then you have a problem with the fuel diaphragm (the smaller one, #2 in the drawing below).  It could be that it's not seating properly, or has a hole, or is assembled in such a way that the spring isn't doing its job.

[fudgie]

 I just hate to lose that slight extra mileage from reserve... 

But you get longer main tank. You still get the same distance on oem as pingel.

[Gary]

If it's letting gas through without vacuum, then you have a problem with the fuel diaphragm (the smaller one, #2 in the drawing below).  It could be that it's not seating properly, or has a hole, or is assembled in such a way that the spring isn't doing its job.

O.K., took it apart, 2 times, checking and messing with #2 for a better seating position. The 2nd attempt was the ticket. 

Thanks for the feedback Gryphon Rider, very much appreciated.  That was my first rebuild. Last time I just replaced the assy.

Now I should probably look at my fuel/vac lines since I do tend to get some popping on decel...