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Been gone for about 4 months, started it yesterday (still amazed on how fast it starts) but the air won't get over 80psi or so. When I shut it off I heard no obvious leaks.

I remember something about certain systems activating at set pressures so I'm hoping that leads me to the culprit. I'd like to get it fixed today. Fingers crossed.

Thanks.

Try changing the governer , would be a good start

I have seen the line between the air compressor and the air dryer fail. A huge air leak would limit the build and the line would depressurize almost immediately. System air is contained by the check valve at the dryer so air from the system would not flow back to the failed line.
Will the system build a little higher with the high idle turned on?

I had symptoms like this once. It was a sticky governor. I could smack it with a screwdriver handle and it would work. I ended up replacing it when I got home from the trip I was on,
and then tore the old one apart, cleaned and greased it, and reinstalled it. It's been working fine for about 12 years.

Quote from: gumpy on August 27, 2014, 07:59:43 PM
I had symptoms like this once. It was a sticky governor. I could smack it with a screwdriver handle and it would work. I ended up replacing it when I got home from the trip I was on,
and then tore the old one apart, cleaned and greased it, and reinstalled it. It's been working fine for about 12 years.   

    Almost exactly the same for me, but I kept the new one on it.   It wasn't a lot of $$$$$.  (And 70-80 seems about right.  Mine would air up to ~75 in 19 seconds or so and then stick there.)

First thing is the pressure protection valve is what opens at around 65 psi to let air into the auxiliary and suspension systems, so if you can air up to 65 psi or thereabouts any problem might be past the pressure protection valve.  This includes the governor, which senses pressure from the auxiliary air system on the MCI.  If it's the governor opening early you could also get the air dryer purging, if the governor tells the compressor to stop compressing it also tells the air dryer to purge at the same time.  I would isolate by first filling the air system with a separate electric air compressor to see what happens.  If it can't get past 70 psi either it isn't the bus compressor or governor, if it can then by all means the first thing would be to change the governor.

Brian