Hi Gang. New member with my recent purchased Champ

Lion8

Lion8

Active member
Joined
Dec 31, 2020
Messages
28
Location
Southern New Jersey
I have a question for anyone out there. I just bought a 46' Champ from Winter Haven, Fl. My and a good friend started out with the journey to fly it back to New Jersey. Got as far as IVOR, Va., new Suffolk, Va. when the engine died. came back to life, then died. This happened 3 or 4 times. We landed in a harvested peanut field. When I got out, I saw gas dripping from the bottom of the cowling flare. Had a local A&P come out to check it out. He took the carb. home to check it out. Said the carb was fine. During the last leg, I noticed that the top tank was not draining into the main tank any where near fast enough. I changed the wing tank gas cap to a new one, identicle to the old one. bout an hour of so later, this engine quit. any ideas? Thanks- Lion8
 
If the wing tank doesn't have a vent built into it then the cap is going to have to be vented. I'm not sure about Champs though, if that cap is supposed to be vented or not. Citabria tanks are both in the wings and since the tanks are vented and can't leak during aerobatics, the caps seal tight and don't have a vent built in. Is it possible a Citabria cap was put on your Champ's wing tank and you replaced it with another non-vented cap?

Sorry it's not going that well for you. Is the plane still in Virginia?

Welcome to the site, hope things get better!
Bart
 
Might even need a cap with a little pitot on it.

But wonder why it worked so well through the three southern states?
 
I’ll give you credit for tenacity. Not sure I would keep taking off knowing I had fuel problems. Sometimes water in the fuel takes awhile to accumulate to be enough to cause the engine to run rough.
 
How far down did you run the main tank?
If you ran it empty THEN opened the wing tank valve it would explain the motor quitting, especially if you have a slow feeding system...the wing tanks are there to replenish the main tank only. The flow and pressure head is too erratic to keep the carb happy with an empty main. Also; I'd look at the fuel cap on the main tank. If it's partially (or fully) blocked not only will the motor quit due to a vacuum being created in the tank because air can't replace the fuel that's being used but it also won't allow the fuel to transfer from the wing tank because the air in the main tank can't get out to allow the aux fuel in...
The fuel dripping out of the cowling might have been caused by the same thing...if the valve from the wing tank was still open on the ground and the wing tank had fuel in it the pressure head from the wing tank 3 feet above the carb and no main fuel tank vent would present enough pressure at the carb needle/seat to flood and overflow the carburetor.

Congratulations on the new plane BTW.

Chris
 
Hiperbiper said:
How far down did you run the main tank?
If you ran it empty THEN opened the wing tank valve it would explain the motor quitting, especially if you have a slow feeding system...the wing tanks are there to replenish the main tank only. The flow and pressure head is too erratic to keep the carb happy with an empty main. Also; I'd look at the fuel cap on the main tank. If it's partially (or fully) blocked not only will the motor quit due to a vacuum being created in the tank because air can't replace the fuel that's being used but it also won't allow the fuel to transfer from the wing tank because the air in the main tank can't get out to allow the aux fuel in...
The fuel dripping out of the cowling might have been caused by the same thing...if the valve from the wing tank was still open on the ground and the wing tank had fuel in it the pressure head from the wing tank 3 feet above the carb and no main fuel tank vent would present enough pressure at the carb needle/seat to flood and overflow the carburetor.

Congratulations on the new plane BTW.

Chris
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Thanks Chris. Here is how it went from Fl. to Va. Fl. was warn, We made stops every 170 miles. When I filled the tanks at each stop, I ran the main tank to half full then opened the wing tank valve. When we made an over night stay in Virginia, we came back to the plane to find it covered in frost crystals. As we let the sun melt off the frost,nibdid my normal preflight. We started her up and headed back on course. Started getting bounced around a bit. This went on for just over an hour. When the main tank got to half full, I opened the wing tank. It was unusual this time that the wing tank was hardly draining. I stopped to top off the tanks and to troubleshoot the slow drain. Nothing obvious. The previous owner had a new gas cap in the flight bag.i changed the wing cap. This cap is exactly the same as the one I took off. Both are vented. Engine ran fine for over an hour with the new cap then without warning, engine went to no power. 3-5 seconds. Later, came back to cruise power, This repeated several time until we put her down in the field. We suspect either the needle valve being stuck or possible the gasket in the carb in slightly enough to catch the float.
 
Goodyear said:
I’ll give you credit for tenacity. Not sure I would keep taking off knowing I had fuel problems. Sometimes water in the fuel takes awhile to accumulate to be enough to cause the engine to run rough.
Click to expand...
Just to be clear, This engine ran like a Swiss watch for two days prior to this, so we had no issues up to this point. The engine never ran rough, even when it came back to life after several short quits.
 
The stock fuel caps vent underneath the outer rim. If the rubber sealing ring around the main tank neck is too high it can effectively block the vent(s) in the cap...
Rubber (like most everything else) grows as it warms.
Just something quick, easy and free to check.

Chris
 
Lion8 said:
We suspect either the needle valve being stuck or possible the gasket in the carb in slightly enough to catch the float.
Click to expand...
that would make sense, please let us know for sure what it was once it's all fixed up and back flying.
 
Bob Turner said:
Tell us again why you didn’t change back to the old cap?
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I mentioned in the initial post that I changed the cap then after a time the engine quit. There was no changing back to the old cap, to busy looking for a suitable place to put down. It is 1 day away from getting back in the air (with the old cap). Had a very competent IA take the carb apart for inspection. He found no smoking gun. He replaced the float with a new type-Non-metallic). I bore scoped both tanks. Both were clean. Replaced both flex fuel hoses. Nothing left to do but fly it.
 
Would have been nice to find something out of place but if you've gone through everything and there's nothing left to check, might as well fly it.

Did the airplane fly regularly before you bought it and headed home?
 
Bartman said:
Would have been nice to find something out of place but if you've gone through everything and there's nothing left to check, might as well fly it.

Did the airplane fly regularly before you bought it and headed home?
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Hey Bart- Yes, the plane flew regularly and was hangered in Winter Haven Fl. As I said, it flew great for two days. I have just the cowling to put on then ready to fly again. Spoke to the IA who just rebuilt the carb on the possible Float issue. He said not on this model. Never did this engine show any signs by running rough. Some tale today that is the wing tank valve being open in the low pressure area could have been the culprit, but then the main tank cap had vent holes as well. I'm thinking of replacing the cap with a 'ram air' cam. That would put a positive pressure on that tank. The ram air tube would be facing into the wind and out of the strong negative area of the wing.
 
Ok, having read thru this entire post again I don't see where you verified the MAIN fuel tank cap is venting correctly. The 13 gallon main tank cap vents are underneath the cap rim. Is it possible that when you got "bounced around a bit" (which was prior to the motor quitting the first time) the boot cowl shifted and the rubber tank neck sealing ring blocked the vent holes in the cap?

I can't see any scenario where the wing tanks would cause the motor to quit as long as the main tank had fuel in it and was working properly (fuel out to the gascolator and air replacing the fuel).

Chris
 
Chris, You have a very logical suggestion. I will check that out tomorrow. That idea was not brought up by any of the other guys in the hanger. I'll ask them tomorrow. i hope you are right on with that suggestion as I am out of ideas. My 80 some year old IA who just rebuilt the carb, suggested on the first start that I raise and support the tail in the flying config.(tied down of course) and run it for some time to see if I can duplicate this problem..
 
what engine do you have?

I don't know champs well, but I do know t-carts. I imagine that the fuel systems are very similar. I agree that the aux wing tank draining into the main tank is a separate issue, that would not affect engine operation as long as the main tank has fuel. The main tank will have a separate venting system as described above.

This is more me thinking out loud, head scratcher for sure
 
Taylorcraft, huh? L2 with wing tanks. Gauges are just ugly clear tubes jammed onto 1/2" nipples. Any suggestions? Tomorrow I will cut them off and attach two stubs of fuel line, hoping for a solution after I get all the Polytone on - in March sometime.
 
One more possibility;
Carb ice.
You don't perchance have a low pitch (climb) prop on your bird? In cruise, how far back do you have to pull the throttle to keep the rpm below red line?
As to running the plane with the tail in the air, because the Champ doesn't have a fuel pickup line in the tank rotating the nose to level flight attitude doesn't change anything regarding fuel flow. The Champ has a hole in the bottom of the tank (sump) that the shut off valve is screwed into...if you've got useable fuel in the tank the outflow won't change unless you're inverted!
BUT, if you DO decide to do the tail-in-the-air thing be sure to video it...just in case. 🙃

Chris
 
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carb ice in an interesting possibility.

@Lion8 you said you replaced both flex lines, is the line from the wing tank to the main tank a flex line? I'm not that familiar with Champs, sorry. :)
 
Tangogawd said:
what engine do you have?

I don't know champs well, but I do know t-carts. I imagine that the fuel systems are very similar. I agree that the aux wing tank draining into the main tank is a separate issue, that would not affect engine operation as long as the main tank has fuel. The main tank will have a separate venting system as described above.

This is more me thinking out loud, head scratcher for sure
Click to expand...
Bartman said:
carb ice in an interesting possibility.

@Lion8 you said you replaced both flex lines, is the line from the wing tank to the main tank a flex line? I'm not that familiar with Champs, sorry.
Click to expand...
I'm not thinking in that way of carb ice as there was no roughness, no gradual loss of RPM,s, . The engine went to no power then right back to cruise power three or four times. Aiming at fuel cap vents.
 
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