Starving C-65 engine

[EDGEFLY]

In two consecutive tests my Chief burned 8.3 and 8.4 GPH! ny guesses on what is wrong ?

Dale

[DELCOM]

My guess......... It's leaking somewhere externally that does not show.
Just a guess

What eng.
What tanks
Running rich

lots of questions

Del

[EDGEFLY]

Del,

Where could this unseen external leak be? Overnighting in the hangar shows no leakage/drainage etc. and fuel level doesn't change during non-op periods, so I conclude that this has to do engine ops. The other remote possibility I can think of is the tail-up orientation while in flight. This is a '46 Chief with only the main tank being used. What more can I say about the engine ? It is a standard C-65 with no fixes/soup-ups/mods being flown @ or about Max Gross Wt. w/approx. 10-12 gallons of fuel on board. Running rich? Maybe, but if so, it must be a static engine setting given that there are only Fuel On/off, Throttle & Carb heat to manipulate. The engine is using Phillips 20W40 oil, has good compression readings and was majored just 160 hours ago.

More Questions ?

Dale

[N86250]

You have an A65 engine I think. No provision for electric starter or generator. Although there is reference to a C65 it is so rare that most guys have never seen one. Just to keep the Gods happy.
Some places for fuel to disappear.
Through an unlocked or worn primer into the induction and burned by the engine. 2X normal consumption should be fouling spark plugs. Maybe it doesn't leak when the engine is stopped but engine vacuum can be enough to pull fuel past worn seals or Orings in the primer. Are you running rich enough to foul plugs? If fuel is going here the plugs should be very black with carbon. Carburetors have been overhauled unnecesarily because the primer was not locked in.
Another place is back through the auxiliary fuel valve into the aux tank filling it and out the overflow in flight. The old brass auxiliary fuel valves can be stubborn leakers. Do you fuel the main only before flight? Do you fill the main after flight before putting the airplane away? Did the aux fill itself?
If either the primer or aux valve is the leak, you may not find it easily unless you disconnect and plug off the appropriate line at the fuel tank or main fuel line. If the line is plugged off and the problem goes away, you found the problem.
You may have a leak that is vibration related. Engine RPM at cruise and it leaks. Engine at idle or off and no leak. A cracked hose or metal line may seal at rest and only leak when shaken, but that is rare.
An unusual source for a leak is the carburetor. Is the bottom half containing the float bowl separating from the carb body? Engines have run almost normally while splashing volumes of fuel out the separation while the screws continued to back out . Again it only leaked when bumping and bouncing. The float needle shut off the gas flow like it is supposed to with the bowl full at rest. I'm guessing this Chief is new to you? Does the PO admit to having this problem?

[jc pacquin]

I lost gas out of the Stearman years ago. It was the gas cap. It allowed gas to leak out and down the wing but I caught this pretty quick as it came right back at me! You might check the gas cap carefully. How about down in the fusalage, any sign of gas down there? JC

[Nathan K. Hammond]

I'd start with cheap and easy...

Look for fuel stains after a flight...
Cap the primer...
Send the carb off to get rebuilt...

An incorrect float setting and/or collapsed float will cause it to run rich.

Does the carb drip if the fuels left on and there's a full tank? (float level)
What color is the inside of the exhaust and stain on gear legs/boot cowl? Grey is good, black is rich.
What RPM do you cruise at?

nkh