throttle sticking

[hercules736]

Hi guys I am new to the nitro world and I own a savage x 4.6 ss that I bought online the truck was put together by a guy who has raced trcucks for quite a while so everything looked real good when I received it,he even called me on the phone and he told me the first thing I need to buy is a fail safe, well I was to eager to run the truck so I started it ran it slowly for a little bit,then suddenly it took off with my finger off the throttle and trying to apply brakes there was no response it kept going at full throttle into a tree busting the hub on the front wheel.after that point I fixed the truck( luckily not much damage) I installed a dynamite fail safe thinking this would solve the problem, well it didn't the truck has taken off again and this time just flipped over,and was running full speed the tires looked about 6" in diam. I never can tell what the problem is once I shut it off.Took it over to dads house to install some new aluminum A arms ,then fired it back up and it seem to run flawlesly I was reall happy. Sat. morning was excited to run the truck took it up to the woods just to have it take off on me on the first start.I checked the truck and there was no response to the throttle servo so I need to replkace this, does anyone think this sevo could of been the problem or do I have other issues > SOMEBODY PLEASE HELP!

 

[Rolex]

With the engine OFF, but the radio and Rx on, pump the throttle and brake and watch for any problems.
Next, with the trigger in FULL throttle position, shut off the radio. If the servo worked correctly, but now it doesn't return it to idle, you haven't set up the fail safe correctly.
For future reference, NEVER start an engine till you know for sure that the electronics and mechanical linkages are all working properly.

 

[NitroRC4Life]

maybe you want to try a throttle return spring if its gettin hung up or check your batts cause thy might be dead!! JM .02

 

[olds97_lss]

Since the guy knew what he was doing, it should rule out linkage alignment issues... but, that said, you should make sure that your carb isn't at a weird angle in reference to the throttle pivot. The rod going to the carb should be as parallel as possible to the carb slide movement and as close to being on the same plane as possible to the ball end on the carb slide.

Here's mine with an LRP28 in my savage:

Notice how I have the ball/arm on the carb slide turned towards the front to keep the linkage parallel with carb movement.

Same truck, but an XTM 24.7 engine:

Notice how the carb is twisted a bit to align the slide with throttle wire movement. Should have probably just twisted the arm on the slide itself like I did on the LRP... but if I remember correctly, the XTM ball end arm was a bit shorter than the LRP so if I had rotated it forward, it would have made the alignment of the ball end not be on the same plane as the wire, which could cause binding.

All that said, it could very easily be your throttle servo freaking out on you. They do fail over time and throttle servos are usually the first to fail electronically since they almost always sit upright. This allows any standing water to wick it's way down into the servo and fry it. I've ruined many that way and they almost always go WOT exactly when you don't want them to.

 

[silverbird02]

I would make sure the failsafe is setup right first,then check the servo for binding and proper operation then always a good idea to have a return spring on your carb to help your throttle return.