Suspension not filling up...??? Tag pressure not going up???

[jim riordan]

I might of misread your post...main pressure guage only 75 pounds? sb 120, possible leak in air system. run bus pressure up shut off buss (carefully listen for leaks.). I had to replace the air dryer, in front of the rear axles in the center of the coach, underneath, this helped with the system spped in filling.

Jim Riordan

t3brian wrote:

Hello...All... as always I greatley appreciate any assistance from the
group...

I am getting ready to make the journey to
the Q-ralley and I went to
drive our 84 PT-40 for a quick trip and I cannot get the suspension to
fill....

The front & rear pressure reads 75 pounds but the tag pressure is
zero.....

I have filpped both dump switches repeatedly but no change....

any suggestions????