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recently acquired a small gas powered air compressor powered by a 6,5hp 126312-0043-B1..
My issue is it immediatly cutting off at idle when the regulator cuts the throttle back. Brand new Briggs and Stratton carburetor, fuel line, cleaned tank, new spark plug. I do not lose spark when this happens. Valves are adjusted to spec. Flywheel key is not sheared.
runs like an ape at full throttle.. just when the regulator puts air to the throttle to idle it down, it'll kill it, which from what i gather, its not supposed to. It does this 8 out of 10 times.
its a coleman powermate CT5590816.02

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When it cuts back to idle does it unload and vent the compressor output?

Hmmmmm. I may have been misunderstanding this thing.
When it throttles back at 130PSI the only place air comes from is the line that runs up to the throttle actuator, it does have a larger relief valve on it, and it doesn't let air out at 130psi.

Gas powered compressors usually have some type of unloader connected to the throttle control that vents the output of the compressor that is still turning although at a lower speed. If it doesn't vent the head pressure it can kill and idling engine.

So there's a sticker on the compressor, 10.9cfm at 90 psi, MAX PSI 130psi... looking at the unloader, filled in some engraving on with the paint pen it so i could read it better, the unloader says 175 psi on it.

36 is the pilot unloader valve

36 has been replaced.

what im wondering is if the valve below it is supposed to open up as well?

There is usually a vent on the unloader valve that vents at idle.The valve below might be the the over pressure blow off. Not sure where the unload vent is on that one. Have you adjusted the pilot valve?

Hammermechanicman said:

There is usually a vent on the unloader valve that vents at idle.The valve below might be the the over pressure blow off. Not sure where the unload vent is on that one. Have you adjusted the pilot valve?

Click to expand...

I haven't, I just left as it came out of the box.
Whenever it idles it down it let's a good amount of air out. Just not enough I guess.

Here is question. Does air continuously come out even when the unit is shut down? If so the main check valve is not sealing off as it should.

I think so.
After the unit dies. Air is still coming out of throttle control air line.

If you take the belt off does the engine idle ok with the control pulled to idle position?

Hammermechanicman said:

If you take the belt off does the engine idle ok with the control pulled to idle position?

Click to expand...

Yes

Still sounds like the pilot/unloader is not venting the compressor when it goes to idle.

When the engine stops the tank shouldn't be venting. Where is the air venting from with the engine stopped?
Number 19 is the check valve. It is very common for those to leak. When they leak it can screw up what the pilot valve does as it leaks pressure back into the compressor.
looks like the check valve is leaking instead of sealing off and letting the head pressure bleed off through the small line from the check valve to the pilot/unloader valve and out the small hole on the valve.

The only place air comes from when it idles down and dies is from around the idle control shaft that pushes the linkage on the throttle.

Here's a video of the only place air is escaping.



Removed the #19 check valve, appears to be in working order, easily opened and closed, I cleaned it up and reinstalled, still same issue

Don't think I have seen one do that. Just for grins pull the small line off the 19 check valve and see what happens when it kicks down to idle.

I will get a SHORT burst of air from here when it shuts down. This is the connection from the #19 check valve

That is where the the compressor vents when the pilot shifts to idle. If you pull the line from the check valve it should unload the compressor and not stall the engine when it shifts to idle.

gotcha.
im going out of town tomorrow so ill try that and report back on sunday or monday

So I took the line off from #19 check valve. I get a constant flow of air from that fitting, but it'd above the check valve from the main tube from the compressor.
I idled it down manually and it still died.

If the compressor is being vented when engine goes to idle maybe the engine idle speed too low possibly? There shouldn't be much load from the compressor at idle if it is being vented. Not sure what's going on.

Yeah I tried raising the idle, no bueno.

I chucked that demon possessed POS in the scrap pile this evening. It's not worth for what else I could be fixing with my spare time. Thanks for all the suggestions.