You can get nice electronic ones to replace those TB20 ones Peter, pretty cheap too. The one I fly has replaced all the needles with electronic gauges.
Our Commander has a strange phenomenon….When it is on both, it feeds more fuel from the left tank. We have had the fuel system and valve system checked numerous times and there is simply nothing wrong with it. So if you fly around on BOTH all the time, more fuel feeds from the left so you have to go to right to balance the tanks.
When flying on left or right it is fine too. We have come up with all sorts of theories regarding pressurization of the tanks etc., but no idea why it does this.
Uneven fuel feeding is a very difficult thing to figure out. It is very common with all strutted Cessnas. It has to do with venting most of the time.
In my aircraft, it works pretty well but when I choose to run on one tank only, I barely notice the effect of uneven fuel distribution. You can easily trim it away and I never noticed any loss in speed.
You can get nice electronic ones to replace those TB20 ones Peter, pretty cheap too. The one I fly has replaced all the needles with electronic gauges.
Do you mean the Moritz gauges? The company has vanished.
If you mean one of the JPI products, which one and what is the transducer?
it feeds more fuel from the left tank
Probably flying very slightly out of trim. This is difficult to fix because you are looking for only a few mm, across a distance equal to the whole width. In the MM there should be a reference for laying down a spirit level, and a precision level would be a good start. Then attach a precision level in the cockpit somewhere (the ball on the AI is not good enough) and go for a flight. The AI and the TC are no good either because they will self erect to “whatever” anyway. The foregoing unfortunately assumes the wings are screwed on exactly straight, which they rarely are.
when I choose to run on one tank only, I barely notice the effect of uneven fuel distribution. You can easily trim it away and I never noticed any loss in speed.
If its a low wing plane plane with dihedral you notice it as the outboard fuel burns off. I switch tanks initially by ‘feel’, drawing fuel to keep roll in trim.
If you calculate the air stagnation pressure available from the speed of the plane, there is enough to support substantial difference in fuel levels from one tank to another, assuming independent vents, one fuel cap on backwards etc… but if the tanks share a common vent line it’s hard to understand where a tank pressure difference comes from.
We have capasitive fuel quantity metering system which is accurate when calibrated. Thats fine and more reliable than float type sensors. But problem is that we use both avgas and mogas and mixture of these. The difference of capasitivity between these two qualities is quit remarkable. So the fuel flow meter is really needeed and the only way to find out how far to continue.
Like these ones
What is the make and what is the transducer?
They would need a major rework of the avionics stack, being taller than the previous ones.
Indeed Bonanza have a rather sluggish fuel selector not very well visible left down, however I never thought it was difficult and its part of my basic check list in most flight phase changes. My bird is undergoing a tip tank install currently. Fuel management will become a bit more complex, given the fact that that the fuel is electrically pumped from the tip to the main tank. The procedure would be, burn the fuel from the main tank for at least 1.5 Hrs, switch the main tank to the other side, select the opposite tip fuel pump on. Watch the opposite fuel QTY rise again slowly. Switch the main tank again after 1.5 hours select the opposite tip fuel tank for the same.
All fuel floating fuel senders are notoriously unreliable. Running a tank dry confirm if everything is working as supposed… 
Of course having a shadin fuel flow helps also..
Just had a guy tell me a story about how he flew a 206 on a low level nav, (the C206 doesn’t have a “BOTH” setting) and he switched tanks, almost.
Only after the engine stopped, whilst flying at 1000’ AGL, he noticed the fuel selector wasn’t completely on the right tank…
I have a sad tale to tell regarding fuel selectors;
A friend of mine, who had previously asked me to fly with him as safety pilot in his Mooney 231, had run a (left) tank dry on a flight to ELLX at FL100 or so, he switched to the RIGHT tank and flew on without concern . There both tanks were filled to the brim and he returned to his homefield, about 50 minutes flying, all on the RIGHT tank.
Two days later he wanted to make a local flight with some family members. He did the normal run-up on the RIGHT tank and when on the runway, about to take-off, he did a last second checklist and switched from the RIGHT tank (about 2/3 full) to the LEFT tank (showing 100% full). There was just enough fuel in the line between the fuel selector to get him airborne and at about 100 ft, the air that was sitting between the outlet of the LEFT tank and the fuel selector had travelled to the engine. The engine stopped abruptly. He tried to get the engine restarted instead of setting up for landing immediately. , I know from experience with this aircraft that it can take 10-20 seconds before the engine catches again. The gear was already up and he made a hard belly landing on the last few remaining meters of the runway, injuring himself and his passengers. He spent about 6 months in revalidation for spine injuries. The aircraft was damaged beyond repair, wing spar bent, cabin cut open by rescue services, luckily there was no fire since it took many minutes to extract the passengers from the aircraft.
Moral; check fuel flow from both positions before the run-up, after run-up don’t change tanks. He also should have drained the fuel strainer underneath the selector while switching to both tanks in sequence. In this case he over-used the checklist.
