Always Check your Fuel Selector

[Wildhorsesracing]

I picked up my plane from windows and avionics upgrades today and went thru the checklist twice to make sure I checked everything and was ready for flight.  I checked my fuel selector valve by looking at it and assumed that since it was pointing at the left tank and the engine was running then all was well.  I did not actually switch the valve between tanks but simply assumed it was where I left it on the left tank.  

 

I was on a 5500 ft runway, took off, started to climb @ 100 mph and raised the gear - the engine stumbled and sputtered like it was going to quit.  I leveled off and looked at the boost pump switch: on - so I reached for the landing gear assuming I was going to land in the second 1/2 of the runway. I immediately thought to try the fuel selector to make sure it was in the Left tank detent.  It wasn't!  Once I clicked it in the engine roared to life and I went around the pattern (three times!).

 

I will always check the fuel selector valve by manually switching it between tanks from now on when my checklist says "Fuel selector: Fullest Tank".

[Rwsavory]

A very important point for all of us to remember.  Thanks for sharing your experience.  

[201er]

Thank you! Excellent advice! One that I learned like this was to check the emergency gear override is fully locked or it won't let the gear come up. I had a takeoff where the climb was unusually anemic and it took me a while before I realized the gear wasn't actually up. I also realized that on a short field obstacle takeoff, this could be fatal.

[jnisley]

The very first item on my preflight is to sump the fuel and cycle the fuel selector, that way if for some reason the fuel drain valve would stick open I would see it during the exterior preflight.

[Bennett]

Excellent advice. I like choosing which tank to use as the first item in my preflight. Had a friend who was badly hurt, along with his passengers, when he changed tanks to the fullest tank, or so he thought, before take-off. I visited him in the hospital, and he recalled reaching down to turn the selector, but didn't "jiggle" it for digital feedback. Better to learn from other's mistakes. This forum is really useful in this (perverse) way.

[Lood]

The very first item on my preflight is to sump the fuel and cycle the fuel selector, that way if for some reason the fuel drain valve would stick open I would see it during the exterior preflight.

 

+1 and strange enough, my Mooney will maybe give a cough or two when trying to start it with the fuel selector closed, but it won't run.

[jetdriven]

A carbureted Mooney can run with the fuel selector halfway in the detent on the ground, the fuel flow is only 2-3 GPH and it will keep the float bowl full. When applying takeoff power, the demand for fuel is greater than the fuel selector can give, and it runs fine for 20 seconds until the float bowl in the carb runs dry.  Then bad things happen.

 

A fuel injected Lycoming, I dont think will develop takeoff power with a fuel selector not fully in the detent, the fuel pressure falls and it will run rough like the mixture is set too lean. There's no revervoir of fuel like a carburetor has to mask the low fuel flow.

 

That hole that fuel passes through in that fuel selector is only 3/16" in diameter, I found out after having just rebuilt ours.  FWIW there was another thread about switching tanks, and I try all selector positions, then select the fullest tank before start and wont touch it again until cruise.

[yvesg]

A carbureted Mooney can run with the fuel selector halfway in the detent on the ground, the fuel flow is only 2-3 GPH and it will keep the float bowl full. When applying takeoff power, the demand for fuel is greater than the fuel selector can give, and it runs fine for 20 seconds until the float bowl in the carb runs dry.  Then bad things happen.

 

A fuel injected Lycoming, I dont think will develop takeoff power with a fuel selector not fully in the detent, the fuel pressure falls and it will run rough like the mixture is set too lean. There's no revervoir of fuel like a carburetor has to mask the low fuel flow.

 

That hole that fuel passes through in that fuel selector is only 3/16" in diameter, I found out after having just rebuilt ours.  FWIW there was another thread about switching tanks, and I try all selector positions, then select the fullest tank before start and wont touch it again until cruise.

I select least full before startup, then select most full before run-up... (carburated Mooney) does anyone see any issues with this? It ensures both positions do work and use most full for take-off.

Yves

[jetdriven]

How long is that fuel line from the fullest tank to the carburetor? If it contains water you will find out just after the gear comes up. Better to take off on a know fuel supply and sample the other tank at a safe altitude where you have options.

[Hank]

Yves,

 

I always crank on the fullest tank, it's right there on the Pre-Start checklist as Item #1:  Fuel Selector Handle--SET for fuller tank.

 

It also shows up on the Before Takeoff Check right after checking flight controls for proper motion, and as a quick check again immediately before takeoff.

 

I've read NTSB reports of C-models reaching 100-200' agl then the engine quits, usually with poor results; some have happened at fields I fly to, where the only option is which tree to hit. There's a reason everyone says "don't change tanks right before takeoff." If I reach the hold short line to do my runup, I'm taking off on the tank that got me there. Sometimes I realize that I should have switched, but I wait to level off first; I rarely go far with a nearly-empty tank so the climb will be short.

 

I think we have a greater risk than the injected engines. I've been told that our engine will run 30-60 seconds on the ground after switching the fuel to OFF. This may be something to test once spring temperatures arrive and it won't be difficult to re-start. Crank up, taxi out of the way, Fuel OFF, start timer and see when she burps then quits. Fuel back on, run the pump to re-establish fuel pressure, crank back up.

[treebobboy]

I have already done the "start the engine with the fuel valve in the off position" test.  I was going to taxi to a friends hangar on the field about a thousand feet down the runway.  After normal start, oil pressure in the green, I started my taxi.  I immediately noticed fuel pressure fluxuations and half way there (500 ft) the engine quit.  I coasted on down to his hangar and cleared the runway.

I have a G model, so I now know there is no way I can start my engine, taxi to the closest "hold short", do my runup and then proceed with full power takeoff.  Good thing to know, but no replacement for a written checklist.

 

Mike

[Marauder]

My normal pre-flight includes sumping the center sump from both tanks and leaving it on the fullest tank. I will not touch the second tank until my normal in flight switchover point (usually after 1 hour of running). If I were to run into a problem (ex. water) at the switchover point, I would switch back to the first tank and find a place to set down and troubleshoot.

[Piloto]

One important item to check at annual time is the fuel selector knob set screw. If the screw is loose you may end up with the knob in your hand and no way to switch tanks. You can tell when the set screw is not tight by feeling some slack when rotating the knob.

 

José 

[jetdriven]

Jose brings up a very good point, if that fuel selector handles comes off or even loose in flight, you are pretty screwed.  The M20J SMM shows Loctite blue on the set screw, and I get down on the floor and inspect it a few times a year as well.

[Bennett]

I keep a very minimalist tool pouch in the pilot's side footwell pouch that along with a couple of small screwdrivers, also contains a small needle nose vice grip. If a handle falls off, i will try to use the vice grip on the shaft. Crude, but it just might be important one day. The bigger tool kit is in the baggage compartment.

[Greg]

After the fuel selector got jammed in the off position (2000 AGL ) and the prop was turning the engine I seemed to have a little extra strength in my fingers and managed to roll the selector handle past the little upholstery screw that found its way into the little cup that the selector handle resides in. Now I really check for debris around the selector handle before moving it.

[OldGlassMan]

The fuel selector should also be an annual item.  A few years back, mine was getting harder and harder to rotate.  I had my guy pull it and take it apart -- we found that over the years, dirt and grime from the floor had built up a deposit around the shaft where it went through the floor and also into the valve itself.  Some Mouse Milk, some mild solvent, a rag and a little elbow grease removed the deposits, and it worked like new.  One word of caution, if you use solvent, do not let it get near the seat seals in the valve, they are rubber, or maybe neoprene, and the solvent can do them harm -- use a Q-tip to keep it on or near the upper shaft area or the upper shaft housing.

 

RFB

[jetdriven]

it is in the annual/100 hr inspection checklist:

5. Inspect fuel selector valve for operation & proper
indication. Verify positive valve selection while rotating
fuel selector valve through selection range. Tighten/
Loctite set-screw if required.

 

We just rebuilt ours. It was drawing air and manifests itself as unsteady fuel pressure above 9K feet.   They are plain old rubber MS o-rings.  Careful with oil etc on the shaft, it damages the rubber.  Whatever you use, be sure its safe for nitrile rubber o-rings.