Help! Stuck open air dump

[DBRV4]

Good morning. I have a 99 National Tradewinds 7372 on a Freightliner XC chassis driven by a Cat 3126. Here's my problem; the generator was dying after starting at about 20seconds of running so I wanted to make sure the start batteries had full charge and to warm the engine in case I had to break camp to repair the generator. It started well and I increased the engine speed to abt 900 rpm as I normally do to warm it up for driving. I dumped the air after leveling the rig last afternoon, however after moving the lever forward to pressure the system... nothing. No pressure. Repeated moving the lever back to dump then fill did nothing. My wife and grandkids are meeting me here in 5 hours and if I can't get pressure I will be involved with getting this repaired, not enjoying their company.
Where to start? The valve gave me problems in the past but moving the lever a bit forward always pressured the system up. Thanks and please respond.
(The generator decided to run, however. Small victories..)

[Unplanned Tourist]

How much air pressure is in the tanks?

There should be a valve that cuts air to suspension and other non-vital accessories at around 80 psi. It may be stuck closed. (pressure limiting valve)

[DBRV4]

Thank you for your reply. I have two gages for pressure and both are reading zero. I have not started it again today, but will report my findings when discovered.

[azpete]

check the dump valve on the front axle. it can be manually opened or closed.

[DBRV4]

Originally Posted by Unplanned Tourist

How much air pressure is in the tanks?

There should be a valve that cuts air to suspension and other non-vital accessories at around 80 psi. It may be stuck closed. (pressure limiting valve)

I skimmed the knowledge base and the boards and I was embarrassed to find many helpful suggestions. A couple caught my eye including yours referencing the 80 psi on the limiting valve and another old post about getting enough pressure to reset that valve...Not sure, but before I was going to crawl under the rig I wanted to try his solution which was getting the revs up a bit. About 1500 rpms. I warm up the beast at around 1000 rpm. I warmed it up then added the extra rpms, threw the lever and viola! A mystery. Pressured up slower than usual and stuck around 65 75 psi for a minute then went up to 120 /130. Made it unscathed across the Sierra and drove like a dream. On new Toyos. I'm crawling under tomorrow (LR jack wouldn't retract fully until I spun it a tad) to effect some repairs, I guess. Thank you all for your replies. It makes a difference to a newbie like me. .
Doug

[DBRV4]

Originally Posted by azpete

check the dump valve on the front axle. it can be manually opened or closed.

Thank you for the reply. I'll be under there tomorrow. Is it obvious whether it's open or closed?

[Ray,IN]

The dump valve opens and closes by a 12V solenoid on the end of the valve. It must receive a signal to close, so, store the leveling jacks, then auto-level the coach, then store the jacks. The store jacks sends a 12V signal to close the dump valve.
This gets everything back in sync again. It cost me a $180 mobile tech service call to learn that information.
IF that fails, do as AZPete said.