fireman7875

My Feedback: (7)

I have two Pee Wee's on two different planes. One ,which has little run time on it, runs strong and consistently for quite a while (I would guess 2 min.). The other has significant run time on it and seems to have trouble finding a good needle setting. The older engine has good compression and is in good shape. Even when I do get a good needle setting and fly the plane the engine doesn't run as long as the newer one (about 1 min.). Obviously I haven't actually timed the two engines but the newer one runs significantly longer. I took the old one apart and everything is in place so I am confused. Any suggestions?

Thanks,
Brian

jessiej

Have you tried slipping a piece of fuel line over the needle to preclude air leaks? Also sometimes oil can run down the firewall and plug the air intake. Placing washers between the engine and firewall should prevent this.

DesignMan

Often, the problem with PeeWee and Babe Bee type engines is that tiny gasket that goes between the tank and backplate on the venturi. They get squished, harden with fuel, shrink, and leak air in or fuel out. If you can't get a replacement, try cutting small silicone fuel hose down to size. You might also be able to seal it with silicone glue.

jessiej

I had for gotten about that one. For me a washer cut from silicone fuel line worhs best.

jess

BMatthews

similarly to the little gasket the vinyl pickup tubing hardens and can leak air at the pickup nipple. If it leaks air then the setting will get progressivley leaner as the fuel level goes down. I'm assuming here that it's not leaking so badly that it just cuts off. You can fix this by replacing the pickup tubing.

The silicone tubing to replace the spring is an excellent idea too. It's a standard mod for me these days. You'll find you need a washer at the top of the NV to keep the tubing from creeping over the upper shoulder.

fireman7875

My Feedback: (7)

Thanks, guys, for the hints. I believe one or more of them will fix the erratic running. Still, there is the problem of fuel efficiency. Could this be simply an unavoidable product of the engine's age or is it likely something else?

BMatthews

It may just be related to an air leak. You may not be using all the fuel in the tank. Check out the leak options first and then run it. It may be that the engine is fine then.

fireman7875

My Feedback: (7)

Ok, I'll give it a shot. Thanks for the help.

Brian