Well last week I started up my showtime an noticed some smoking from what appeared to be underneath the cowl. Ive taken it apart today. I dont really see anything loose or holes in the lines. I have however noticed the smallest trace of oil along the bottom of the fuel tank inside the fuse. im wondering if this could be from the hole on the firewall...whats the chance that the oil would get blown back in through there??

I think i might just yank all lines and tank - and just replace in an effort to save time and be safe. Do you guys ever just do a complete overhaul of fuel system? If so how often?

Aside from lines and tank...is there anything else I could be missing? Whats the chance there might be a sealing issue with the engine? Im guessing I should probably run the engine again without the cowl on it to try and get a better idea.

An unsealed hole on the firewall will indeed allow exhaust oil to run back into the plane. The only other issue could be a leak in the tank or a fuel line. If you have a leak it usually shows up when you run the engine with air bubbles in the fuel lines. I think I would seal up the hole, check all my nuts and bolts and fly it. Good luck, Dave

If you are worried about exhaust grunge or fuel weeping back along the fuel lines through the firewall then running the engine without the cowl will tell you nothing as that would completely alter the airflow and oil travel. and absolute seal around fuel lines is not neccessary and you can actually do fine with a pretty big hole.

If you have oil grundge under the fuel tank its far more likely from weeping around the bung or around the plug tubes. You may want to tighten the compression screw.

When you get some fuel blowing into the tank area through the line holes it is more of a little mist that will show up on the epoxy sealed wood or exposed fuel tank. If you find heavy oil/fuel under the tank then like John mentioned, you probably have a little leak.
If you have a leak it should be showing up as bubbles in the line like Dave mentioned.
If you are at idle and see fuel dripping on the ground you really want to pull the cowl and look to see where it is coming from. Ihave had pump regulators leaking and didn't notice it until Ispotted the drip.

Looks like its just mist. Ill start it up and check for bubbles. Thanks guys!!

Last year, I was fueling my 4*60 and noticed a cobweb floating out of the carb area. When I shut off the pump, it disappeared. I started the pump again and it was back. What I was seeing was a very fine hole in the fuel line and under prssure, it was leaking. There were no bubbles in the fuel when running. The hole required the pressure of the pump to open it up. You may want to check you lines closely as well as the other good advise. My line was blowing out mid line, not near a fitting, and there was no sign of damage to it.

You don't say what engine you are running, Four stroke are bad about wheezing fuel out of the carb at lower RPM.s If you have a 4 stroke, you may want to fit a velocity stack on the carb. That cuts down the blow out by a bunch. It doesn't cure it completely but it is well woth the minor cost and effore when it comes to keeping the engine compartment clean.

Don

Running a Saito 91. Has a velocity stack and bru-line filter to keep the fuel spray at a minimum

Wheezing!! What a great term Don!!
If that bit of spray bothers you a bit of Silicone slathered {another good term} around the fuel line on the fire wall will cure the problem. I'm kind of hit and miss when it comes to that but I used to do it to all my planes, gotten lazy in my old age. It also keeps the line from vibrating on the fire wall, don't know if that means anything but Ialmost never have any fuel line problems.
Ihate having to reline my tanks so Itry doing everything from having to do it. My gassers get new line every year but I only have three of them so it isn't too bad.
QUESTION: Where are you guys buying your V stacks??

Horizon hobby for saito.