Power valve not opening
Recently I found that the power valve on my 950 carb did not appear to be opening at all. I have it tuned for a lean cruise, but now the AFR readings on the wideband do not richen up when the manifold vacuum drops below the PV rating. In fact it gets even leaner and sags. I did punch it once to get the secondaries open and it took off so fast I didn't have time to watch the AFR! So it's getting fuel.
It used to work perfectly...it's only sat in the garage for a couple weeks and I had last filled the fuel cell with alcohol-free premium so I know it didn't gum up. I did check that the fuel pressure was still 5 psi at idle, and the level is 1/3 up the large sight glasses.
So, today I pulled the bowl and metering block. Everything is pristine, the passages in the metering block appear to be open, and the PV operates smoothly when I apply lip vacuum to it
If for some reason the manifold vacuum is not reaching the PV chamber, then it would be OPEN all the time, which it isn't. The idle AFR is in the high 13's and cruise near 15 where it's always been, so I know the gauge is working. The only thing I can think of now - the gasoline is not getting to the PV somehow. But I could see gas in the PVCR's when I removed the PV and the chamber in the main body looked like it had been wet. So what do I do now?
Recently I found that the power valve on my 950 carb did not appear to be opening at all. I have it tuned for a lean cruise, but now the AFR readings on the wideband do not richen up when the manifold vacuum drops below the PV rating. In fact it gets even leaner and sags. I did punch it once to get the secondaries open and it took off so fast I didn't have time to watch the AFR! So it's getting fuel.
It used to work perfectly...it's only sat in the garage for a couple weeks and I had last filled the fuel cell with alcohol-free premium so I know it didn't gum up. I did check that the fuel pressure was still 5 psi at idle, and the level is 1/3 up the large sight glasses.
So, today I pulled the bowl and metering block. Everything is pristine, the passages in the metering block appear to be open, and the PV operates smoothly when I apply lip vacuum to it
If for some reason the manifold vacuum is not reaching the PV chamber, then it would be OPEN all the time, which it isn't. The idle AFR is in the high 13's and cruise near 15 where it's always been, so I know the gauge is working. The only thing I can think of now - the gasoline is not getting to the PV somehow. But I could see gas in the PVCR's when I removed the PV and the chamber in the main body looked like it had been wet. So what do I do now?