There are several things you brought up. One of the things that 'jumped' out at me was the reference to the fact that it will go hard lean and take a lot of needle to richen, where the engine will drop into blubbery-rich running.

This indicates that you are getting air agitated into the fuel inside the tank...also known as "fuel foaming". Engine vibration causes this. You'll have to either add more foam rubber around the fuel tank or take some out. If not enough rubber, the tank's not insulated against the vibration, and if too much, the foam is compressed so much it's not working.

If you go with higher nitro, you'll have to add oil to help cool the engine. Nitro acts as a oxidizer in the fuel and adds power. More power means more heat. Unburned fuel and oil thrown out the exhaust take heat with them. If you're running 20% nitro, you should add oil to bring the oil content percentage to 20%. 25% nitro would need some more.

With a pump, you can usually set the engine right at peak RPM and fly it that way. The pump should prevent leaning as the fuel level in the tank goes down.

If you disconnect the pump from the carb and spin the engine, you should get a good stream of fuel. That tells you the pump's working nicely.

If your pump needs repair, send it in. We can't repair the pump, but we can do an exchange if under warranty, or offer a discount on a new one.

We hope you find this information helpful. Should you have any further questions or concerns, please do not hesitate to contact us at this email address. (Please be sure to copy all previous emails into any future questions.)

DID YOU KNOW that our web pages now all contain FAQs? (Frequently asked questions) Please drop by and take a look! We hope you'll find the information helpful and valuable to you.

Sincerely,

Bill Baxter, Manager
Hobby Services
1610 Interstate Dr.
Champaign, IL 61822
USA

Phone: 217 398-0007
Fax: 217 398-7721
Email: [email protected]
Web: http://www.bestrc.com