Pumps air when valve is opened from 0 to about 50%. When valve is increased it shuts pump off and stops blowing air. Any help would be appreciated. Thanks!
Is engine speed increasing when you open the valve, or just maintaining at idle? Is it shutting off instantly like a sensor fault or ramping down and dying like it's running out of fuel? Either way, first check is always the fuel supply/filters and what the inside of the tank looks like. Tow behind air compressors have always come in #1 for me for the most junk swimming around in the fuel tank. Also, engine air filter clean?
Yes sir, engine speed increases like it is suppose to. Engine runs good it does fine when you open valve up until it gets to around 50% open then it just stops pumping air and engine goes back to an idle. you can close the valve and open it back up and it works again until about 50% then does it again. its kinda like when it gets to a certain psi it just shuts pump down.
Sounds like it's going into unload mode and dropping back to idle. Post up your model and serial. Most of the Doosan/IR setups have the same procedure for checking and adjusting the regulator, but don't want to give the wrong info.
That tag covers the trailer, the equipment tag should look like this. I attached the sheet for the speed and regulator adjustment, since it's the same for most of the IR 185 models, and since your trailer is from 2005 it should be the same. Also check how dirty your compressor air filter is and while off see that the unloader valve underneith it isn't sticking. If the filter is clogged up (and it's in a clean enough area), you can run it with the filter off and see if you have any change when loading it up.
Look on the radiator/fan shroud. Should be an aluminum tag riveted to it or directly above your control panel.
Same linkage adjustment for your model as the one I posted. Let us know what you find after going through all the checks and adjustments. https://dealers.doosanportablepower.com/emea/documents/Service/01_Portable%20Compressors/Compressor%20Manuals/16b_USAmade_P185WIR_P185WJD_P185WYM/P185_XP185WJD_APR05_CPN22610380_gb.pdf