250 cfm Sullair races instead of idleing back

by Keith Layman
(Warren ct usa)

Our 250 cfm runs great but on start up the compressor races instead of idleing back after a few seconds. we have to hold back the linkage for several minutes until it stops racing on its own

We have an 1989 250 cfm sullair that operates like new except on start up when cold. It races and we have to hold back the linkage until it finally idles back on its own.

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Oct 29, 2015
more info
by: Anonymous

Yes, we bought it brand new in '89.

This problem has developed over the years. First it started out taking a bit longer than it seems it should have, then a little longer yet and has gradually gotten worse. It hasn't been a big issue to us, just an annoyance.

At our most recent regular service, we thought we'd look around and see if anyone else has had this problem and found this message board and posted.

We do have all the manuals that came with it and with the suggestions offered, we can look at them and begin to isolate the components one at a time to see if we can clear it up.

This issue is a bit low on the list priority-wise, so we'll dig a bit deeper in to it when we have a little more time.

Thanks again for your comments.

Oct 28, 2015
250 cfm
by: Doug in s.d.ca

Have you actually had it since (brand) new?

Did the weather change much or at all between the last time it worked and the time it started?

Oct 28, 2015
better description of events
by: Anonymous

Doug, we've never gone directly to run while the engine races at start-up.

From when it was new, upon start up and immediately releasing the bypass button, it would immediately idle down.

Outlet is closed, pressure is about 50 during the time of idling and warm-up.

Upon pushing the button to run, it would throttle up and build air normally.

Now at start-up, it is full throttle up unless we hold back on the linkage; sometimes for as long as 5-6 minutes.

I can't see the pressure gauge while holding the linkage; I'll get my brother to watch next time we use it.

Then what ever is causing the problem releases or clears and kicks the linkage and idle speed down. Once it kicks down, then we go to run and all is well.

Thanks for your insight and interest on this problem.

I'm going to dig out our manual again and check on the plumbing and names of parts to see if I can match up things for ease of discussion.

Oct 27, 2015
by: Doug in s.d.ca


What's the pressure during this time?

What happens when you go to "run"? Anything?

Is the air inlet closed? If so, then the throttle should also be closed. If not, you're back to the regulator/blowdown valve manifold.

Oct 27, 2015
by: keith

No at start up. When you first start it up, the engine does not idle it runs like it is trying to make air. Thanks in advance for your help. Keith

Oct 26, 2015
by: Doug in s.d.ca

I take it this happens after you go from start to run?

Sounds like the speed control cylinder and/or regulator valve is gunked up.

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