Restricted propane Flow

[TubaPete]

I am having trouble with the flow from the right hand side propane tank in my fifth wheel. (This is when the left tank is empty.)Everything will work off of the right tank except the furnace. When the furnace comes on the system shuts down as if the tank were empty. I can shut down the furnace, wait for system pressure to build up and everything will work, except the furnace.

The system has a small red regulator on the right tank side and I know the tank pigtails have some type of leak restriction built in. So my question is what is the likely culprit, the pigtail of the little regulator?

Obviously I have no idea why the system has the little red extra regulator.

[Old-Biscuit]

RED regulator on off side cylinder is a single stage 30# regulator.........they have been an issue.
They reduce cylinder pressure down to 30# before feeding it across to main 2 stage regulator.

Pigtails have a excess flow check valve---ball bearing style that closes off if pressure on both sides of ball are not equal.
They have been an issue with gumming up and sticking close.

Main 2 stage regulator takes cylinder/high line pressure and reduces it to 0.4 psi (11" WC) to feed propane system.
There have been issues with them.

Which one is causing your problem.......
Hard to tell via internet.
You need to swap cylinders around, try different set ups to eliminate issue
OR throw parts at it.......RED regulator first.

[NC_Hauler]

I had the same problem with mine Pete, I have two 40 gallon propane tanks, you can switch sides just like yours, my selector switch/regulator is located on the drivers side(Left side) of the 5er, the other tank located on the curb side, (right side) also has a red regulator....When I turned the furnace on, using the left side propane tank, there wasn't enough pressure to keep it lit, though it would have enough to cook with, to run hot water heater and to run the refrigerator. I checked hoses for obstructions, found none..replaced the red regulator on the side that couldn't keep the furnace lit....it didn't help..SOOOO, I replaced the regulator on the other where you select what tank you want to use, and BINGO...problem solved :).....Ever since I replaced the combination selector valve/regulator on the drivers side of the 5er, either tank will now keep the furnace going. That was my experience...

[avvidclif1]

A picture would help???