US General Model US1230G low idle shut down

9 years 2 months ago #1242 by henderd4072
US General Model US1230G low idle shut down was created by henderd4072
I've recently purchased a used US General Gas Air Compressor model 1230G with the B6000 pump. The pilot unloader valve was defective on it so I replaced it with one I recently purchased from MTR. I started the pump up and it pumped to 175 psi like it was supposed to, but when it got to 175 psi it turned off instead of kept running at low idle. Now, because I don't know how this particular compressor operates. I need to find out if at 175 psi does the air from the compressor then start coming out of the unloader valve until the air in the tank reaches it cut in psi? If it suppose to, it doesn't. This pump isn't like other pumps I've seen which have air unloader valves to relieve to the compressor from building air during it's cut out cycle. So I'm guessing the model that I have stays loaded even at low idle and that's why it's dying at low idle. Please respond and correct me if any of the information I given you is not correct on how I think this model operates and give me a possible solution to the problem that I'm having on why it's dying out at low idle. Thank You.

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9 years 2 months ago #1243 by MTR-Admin
Replied by MTR-Admin on topic US General Model US1230G low idle shut down
Thanks for the post!

Did you order one of the combination Check/Pilot/Unloader Valves on the webpage below?

www.mastertoolrepair.com/ng-style-combin...er-valves-p-847.html

If so then yes, when at idle (after it reaches 175 PSI) the air should bypass the tank and bleed out of the side of the Pilot Valve; there should be a mesh screen where the pressure would unload from.

Do you have the part# of the valve you ordered? If you had a photo you could upload that would be helpful as well.

After you confirm the pressure is unloading at the Pilot Valve, make sure your idle speed is correct on your gas engine.
There is probably an idle screw that adjusts the RPMs, CW to increase the RPM and CCW to decrease the RPM. You may just need to increase the idle speed.

- MTR

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9 years 2 months ago - 9 years 2 months ago #1244 by henderd4072
Replied by henderd4072 on topic US General Model US1230G low idle shut down
Unfortunately I do not have a picture of the unloader pilot valve because this compressor is currently at my old job and I haven't had time to go pick it up yet. I do have the information of the unloader I bought though.

IMC-ATLAS COPCO Pilot Unloader Valve 1312100497 / Hopefully this was the correct one. If not please advise.

As for the low idle adjustment on the carburetor. I've tried adjusting that already and no matter how much I adjusted it, it still wouldn't stay running.

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9 years 1 month ago #1246 by MTR-Admin
Replied by MTR-Admin on topic US General Model US1230G low idle shut down
It looks like this is the correct Pilot Valve for your model. The cut-in PSI is 145 and the cut-out PSI is 175, which is correct.

It does have the unloader port, as you can see in the photo where the mesh screen is located.

I would also make sure you have no debris in the transfer tube or in the head that would clog or impede air flow to the Pilot Valve and to the tank.

One the unit hits 175 PSI it should certainly kick down to a slower idle speed and unload, however. If not, it may be an engine problem that needs further diagnosis.

- MTR
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