hbrannan

Engine will not run past halve throttle. Idle is good. Have replaced all fuel lines. No leaks. Have had all the gas pros trying to adjust needle settings. No matter what I try nothing seems to work. Next I will replace the carb. Old carb had been rebuilt. Sent engine to Tower Hobbies and the said engine ran fine no problems. Still the engine will not run past halve throttle.

ahicks

My Feedback: (2)

2 things come to mind for me here. The first is a plugged up internal fuel filter (inside the carb). Those plug frequently and are very easily cleaned. Second is not so common, but sounds possible from your description. That's low ignition voltage. When the battery pack draws down to a certain point, it puts the engine into a "limp" mode, cutting power drastically. As mentioned, you don't see it often, but when you do it sounds for all the world just like a carb problem - similar to what you are describing. When measuring that battery voltage to check, make absolutely sure you do that with a draw on it - as in after the systems been turned on for a few minutes.

kerwin50

Mine once sucked a servo screw in and got wedged in the reed block. Very same problem

Lifer

My Feedback: (1)

If it has an external pulse line, that may be leaking. Replace it.

flyinwalenda

My Feedback: (5)

All good suggestions. I would check the ignition battery, then remove the carb plate with the single bolt,fuel pump diaphragms, and check for dirt in the screen. If the fuel pump is blue I would change it to the black or the tan color one. While you have the carb off you can remove the backplate and check the reed block.
It's probably fuel starvation but after this if it still won't run up then the ignition box advance may be the problem.

CARS II

My Feedback: (7)

The OP is saying the engine was send to TH and they said it runs fine, when they run it I imagine the things the had to provided to run it were gas and power ( battery ) with this in mind then those that mention to check the battery under load my have a good point.