Devilbiss wont build pressure but slows down

by Bobby Jewitt
(Canton, Ohio, USA)

I have a DeVil Biss charge air pro model number IRFTV660V-4. I purchased it used not knowing if it worked at the time.

When i got it hooked up it started out running strong. It built up 20psi very quickly. Then the motor and pump slowed way down. It didn't stop but it wasn't building anymore pressure.

It was slow enough i could count the rotations.

Since the initial startup i replaced the piston sleeves, piston ring, and o rings. Same problem.

I replaced the entire pressure switch. Same problem.

Lastly i just replaced the check valve. Same problem.

If i disconnect the tube from pump to check valve it runs great.

If i remove the tube from the check valve to the pressure switch it runs great.

The only part left to replace is the valve plate.

Also i have it plugged directly into my 220 outlet.

Any help at all would be greatly appreciated. Thanks in advance.

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Aug 01, 2017
No power?
by: Doug in

Anonymous Bobby (?) -

That's what I was talking about. Please read all of the following and be sure you understand it before proceeding. You'll probably need to remove at least the cover on the socket to see where the ground is - turn power to outlet off before poking around in there.

What you need to do is figure out what's what on that outlet. Then you can re-wire your compressor plug so it'll work.

Connect one meter probe to a known ground, like a conduit or metal cold water pipe.

Now put the other probe into the various holes on the socket noting what the voltage is.

Two of them should read about 120. The others should read zero - not even a couple of volts, zero.

Now put the meter *across* the two that showed 115 - you should now read the sum of the voltages you got from each one to ground - around 220-240V.

Now see where your motor connects on the cord, and wire it so it's on the 220.

You should also determine which wire is GROUND in the socket. That should be a bare or green wire connected to the outlet's green ground connection. You want your compressor cord's green wire to connect to the outlets green connection. There may be one more connection; that will be neutral - that need not be connected for your compressor, but probably is connected, for your dryer only.

With any luck you can now plug in the compressor, and it will work.

Good luck.

Jul 31, 2017
No power?
by: Anonymous

So I used my multi meter and checked the voltage at the wires going into the switch and the wires conning out. I may have done it wrong tho. The results seem way off. It is fluctuating but only between 105v and 115v. That doesn't seem right tho cause my dryer works fine. So yeah... Back so square one I guess.
Still have no clue. If those readings are accurate tho how would I even go about fixing that?

Jul 31, 2017
by: Anonymous

I'll check that and post the results soon as I can. Thank you.

Jul 27, 2017
slows down
by: Doug in

Bobby -

It's not likely the start cap is the problem, as it's (supposed to be) out of the circuit once the motor gets going. You might want to verify that the contacts on the motor centrifugal switch are opening.

Other than that, have you happened to check the voltage? I know it's plugged into a 220 outlet, but sometimes those are wired differently than you might expect.

Please verify that it's actually 220 *across* the motor, and that it stays at 220 when it's running.

I suspect the voltage may be dropping as the load goes up with the pressure. If not, that'll be a good thing to know for certain.

If it dropping more than say 5 volts, then you need to check the wiring from your panel to the outlet to the motor to make sure everything is good.

Jul 26, 2017
Still no luck
by: Bobby

K. Thought maybe it was the run capacitor because it tested bad. So I replaced it. Still the same problem. Could still be the start capacitor I suppose but it tested ok. I'm not sure what else to do with this thing.

Jul 21, 2017
by: Bobby

Thanks. I'm going to check the capacitors tonight. Fingers crossed.

Jul 18, 2017
Devilbiss slows down
by: Doug in

You might go here first.

Have a look and let us know what you find.

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