OK I JUST GOT MY NEWELY CONVERTED 25 CC WHO KNOWS WHAT MOUNTED IN MY PLANE AND I CANT KEEP IT RUNNING IT KEEPS LOUSING FUEL PRESHURE ITS MOUNTED ON THE FRONT OF A BI PLANE I MOUNTED THE FUEL TANK IN THE COCKPIT TO TRY TO KEEP IT AS LEVEL AS POSSABLE WITH THE ENGINE BUT IT IS STILL SLIGHTLY LOWERBUT I THOUGHT WALLBRO CARBS HAD FUEL PUMPS IN THEM WHAT DO I NEED TO DO OR WHAT AM I MISSING THIS IS MY FIRST GAS MOTOR ALSO WHAT SHOULD I DO WITH THE TANK VENT LINE SHOULD I TAP THE MUFFLER OR WHAT PLEASE HELP ME !!!!! THANK YOU

Don't tap the muffler. What engine type, displacement? If you're losing fuel pressure it's because there is a leak in the lines somewhere. Check all bolts and tighten down good. Also make sure the lines are secure at all connection points. Tie wrap them all, even in the fuel tank itself. Make sure you have a gas conversion stopper also, as the stopper that comes with the tank is usually for glow fuel only. Walbro carbs do have an internal pump, so the tank position should not make a difference. I am by no means an expert in running these engines myself as I to have just gotten started in gas engines. I am just reitterating what I have read in the forums and mags. Perhaps someone else will give you a better idea of what the cause might be. Hope this helps. Ben

Yep, I would almost bet you have an air leak in the fuel system. They just won't pump fuel if you have an air leak. Some of the tubing sold for gas will swell a little after exposure to gasoline. A fitting that seemed snug in the beginning might have loosened. It's a good idea to use some wire to wrap and secure each fuel line connection.

Good luck,
AV8TOR

ok i will check my fuel lines also what should i do with my vent line and what size prop should i be running its a 25 cc and now i am running a 15-8 sound about right ? what do you think?

Just run the vent line from the tank out the bottom of the plane. It dosen't get connected to anything, it's just a vent/overflow. A 15/8 or 16/6 prop is a good place to start.

thanks i will try that this is my first gasser all my planes as of yet have been glow i am going to go try to get this thing running and i am sure i will have more questions