Regulator Low Pressure / Water Heater Burner

[77Overlander]

Searched for this but couldn't find specific information so here goes. Have a 77 Overlander which I was given ( yes given ) a few months ago. Rig has been sitting in Death Valley, CA for at least 8 years w/o being used and may have sat for sometime before. Needed to get the WH going last week (Atwood G610 w/ Jade control). Leak tested all lines, removed all internal WH piping and vacuumed, blew out, inspected, etc. before trying to fire unit. Gas valve was kaput so replaced w/ new Robertshaw control. Now unit fires great EXCEPT for some bizarre behavior at the air shutter on the burner. Ocassionaly the flame will blow back clear to the gas valve orifice and while burning there it makes a chattering noise. Then, flame goes back to normal position and all is well. To me this is acting like low gas pressure. The regulator (a fischer) is original so I'm wondering if I should just replace it w/ a Marshall since the fischer has been sitting so long. TIA

[HowieE]

I would check the flue in the heater first to be sure there is not an obstruction. The regulator should not effect the flame to cause it to blow back once it is lite.