Fuel tank venting fuel

[btbell]

Hello everyone,

Not a T-craft question but still in the same era....maybe someone here can help?....

I've got a friend with a '46 Ercoupe. The left tank is venting fuel in flight (not a cheap proposition with fuel prices being high). He replaced the vented cap with a new one from Univair but it still vents fuel. Anyone out there have any idea where he should start with this.

Also, it shows signs of an oil leak with oil on the side of the aircraft. We did notice that the breather tube terminites inside the cowling...I do not recall seeing this on the other Ercoupe I flew in the past. I would think the breather line should exit the cowl. Could this be contributing? We plan to wash down the engine and have my brother-in-law (AP) look it over to identify if it is leaking from somewhere else.

Side note: I ferried this plane from Alabama to NJ for him last fall. Great flight! After a long winter of bad weather, he finally soloed it last weekend and flew with Tom G, another T-craft owner and forum member.

Thanks in advance for the help!
Brian

[vetdrem]

Re: Fuel tank venting fuel

In my ercoupe, the fuel pump moves fuel from the wing tanks to the fuselage tank at a rate greater than the engine burns it. The fuselage tank has an overflow line that goes back to the left wing tank, and there is a crossover line between the two wing tanks. If there is a restriction in the crossover line, or the right tank isn't vented properly, the fuel overflowing to the left tank may be overfilling that tank, causing the fuel to come out the vent.

May not be the cause, but worth checking.

The crankcase vent on mine extended out the bottom of the cowl an inch or two. But I had a small (pain-in-the-butt) leak that I couldn't find, also. As I was delivering it to the new owner, his mechanic found a small crack in the oil tank just below the flange that bolts it to the engine case.

Happy hunting.

Louie

[NY86]

Re: Fuel tank venting fuel

As mentioned, and depending on the serial number, the header overflow may go to the left wing tank. The cause, however, is a pressure imbalance between the 2 tanks. First, try switching the left and right caps and see what happens.

There is a restrictor fitting in the pump outlet that limits the fuel to the header to a manageable level. Usually if it is missing fuel comes out the header cap onto the windshield, but, depending on the type of cap and other factors it may get forced back to the wing(s) and potentially overwhelm the crossover line.

The crankcase vent should exit roughly midway between the bottom of the firewall and the cowl lip.

John
Skyport Services
Ercoupe parts and service since 1946...

[btbell]

Re: Fuel tank venting fuel

Thanks John and Louie,

I spoke with the owner the other day and told him there were some ideas from the T-craft forum. I will update him based on the latest post. I will try to get his s/n to see if that helps rule anything out.

Thanks to both of you for your help!

John - I see you are close in NY...how far from NJ are you? It may be worth a flight up to see what you think.

Brian

[NY86]

Re: Fuel tank venting fuel

I'm near Albany, but my strip is not Ercoupe friendly. Too short!