dps-130sst tow behind compressor issues

[Midnightmoon]

To start I'm working on an old multiquip tow behind compressor that wont build air automatically. This unit was brought in with the issue of oil in the air and not building much air. The owner replaced the regulator with a non oem one and the oil separator filter. On my first round with this unit I checked throttle diapham and opperation that checked out okay, then the capacity diaphram which was okay. adjusted min air valve to manufacturer spec. Then adjusted regulator to manufacturer spec. Thats where things get funny. The manual says to set at 100 psi with main line open then as you close the main adjust regulator to maintain 100psi. Well...... when thats done there is hardly any air coming out when the valve is opened all the way. It also isnt at 100 psi anymore because the engine rpms stay at about idle. No mater how I adjust the regulator the rpms will not change when you open and close the valve. When you adjust the regulator with the valve open or closed the engine rpms will rise to max rpms and build a good amount of air. There is a solenoid on top of the regulator that has two wires going to it from a computer of sorts. There is 12 volts at the wires but the solenoid did not function. I removed the solenoid and bench tested it. It did not work. I replaced the solenoid and nothing changed. If i jump 12 volts to it while running it has no effect on engine rpms. Ive gone through the service manual a bunch of times and checked and rechecked. The manual isnt very good it says if the engine doesnt build rpms the throttle actuator spring is to tight and adjust but there is no procedure to do so. Ive tried tight and losse and nothing seems to work. The trouble shooting section of the manual is as followed and all these items appear to be working. Insufficient discharge air capacity (clogged air filter, capacity regulator not fully opening). Excessive oil in air(to much oil, maladjusted min pressure valve, clogged oil sepparaator) Engine does not accelerate(improperly adjusted governor linkage, clogged speed regulator, readjust speed regulator spring, engine problem) Pressure to low at full load (improperly adjusted regulator, malfunctioning solenoid, clogged min pressure valve, clogged capacity regulator)
Thats a few of the things Ive check. Ive actually checked all the troubleshooting items in the manual and Im stumped.

When the main valve is opened the engine rpms should increase and nothing seems to make this happen. This is an old unit and noone seems to have any idea as to what to do next including multiquip. Ive talked to 6 different people at multiquip with no help what so ever.

I dont want to throw parts at this but im stuck the only thing Im not sure of is the regulator its a new parker unit. when adjusted it makes more air and increases the rpms but I cant confirm its right. Can any regulator be used?

Any gurus out there that have some advice?
Thanks

 

[TheFixer]

I don't have that machine, but an IR P185. Did you verify the lines are good to the regulator? Getting pressure, not clogged or cracked? My IR uses the nylon lines, so it's possible they break. I think mine uses a air cylinder for the high RPM. Probably activated by one of those solenoids you tested. Make sure that is getting air. Probably need to pull the lines. and test.