Starts Acceleration Automatically

[Skywatch]

Hi Guys,


I purchased a beautiful Dunerunner 32cc just a week ago, started doing engine breakin process as specified in book 1/20 ratio with 1/4 throttle. Just after 45min of drive it started increasing acceleration without even me applying any and vehicle starts rolling itself. Even servo was neutral.


I noticed each time i start the engine within 20 min of drive the vehicle acceleration keeps on increasing till its starts moving without applying any acceleration via remote. We did adjust and lower the throttle knob from Remote but still same problem.


I have also attached a video just to show how crazy it was behaving.https://vimeo.com/138495035


Anyone any idea of this problem. Please help.

 

[Ice_2k]

I'm pretty sure it's a tank venting issue. When it starts acting up again, loosen the gas tank cap. If it immediatelly stops doing it, there's your problem. As fuel is used up, air needs to go into the tank to prevent a low pressure situation. For this purpose, there is a small hole in the tank cap which can pretty easily get clogged up. Just keep one thing in mind: what is happening there is called a 'lean condition'. Basically, the air/fuel mix is getting seriously lean because the carb can't suck enough fuel out of the tank, which means less lubrication and less cooling of your engine.

There are a number of solutions for this problem. There are some kits available out there (work for most, didn't work for me) or you can just build your own, which is what I did. I drilled a hole in the tank cap, put a fuel line through it, run it up and down the rollcage and have a one way valve at the end of it to ensure fuel doesn't go out, just air goes in.

 

[Phill]

Or it could be that your idle is too high but it's not taking effect until the motor is warm.

If venting the tank doesn't work try richening the low needle a tad or adjusting your idle screw.

It doesn't sound at all healthy.

 

[Skywatch]

I did lower the Idol screw and still after few min drive it started doing the same thing. Automatically starts increasing the acceleration and throttle noise till it starts rolling the buggy faster and faster.

But i will check the Gas tank venting thing.

 

[Ice_2k]

from the video, it sounds like the engine sound is getting to a higher pitch, that is a clear sign of lean mix. I'm pretty confident it's the tank vent issue, I also ran into this when breaking in.

 

[Skywatch]

Ok i will definitely check the vent thing.

But one strange thing i want to share. As you can see in the video that engine is acting like getting acceleration and losing then again getting acceleration and losing like somebody isdoing from remote control.

 

[Ice_2k]

Yes, I noticed that. I didn't get that with my car, but I was aware of the possibility of the tank venting issue and, knowing it could damage the engine, as I heard the revs go up by themselves I immediately triggered the kill switch and stopped the engine. I assume that leaving it on for a little while could cause that up and down revs... lean mix causes revs to go up, then it can't get enough fuel to stay on and wants to die, then at lower revs it has enough fuel to stay on and the lean mix again makes the revs go up and so on... just thinking out loud, I might be wrong. However, it's an easy enough check to just open the tank cap when it happens again and see if this is the culprit

 

[Skywatch]

Yeah. I am extremly worried that i may kill the engine. But i will definitely going to check the tank vent thing.

 

[alfred e numan]

Bet ice is right. I do not have the speakers hooked up here on the p-c. If after venting the gas cap- you still have the problem, If you have a aersol can of electronic cleaner laying around, when the engine is running, spray little squirts out of the red tube on the can around the carbs intake gasket- intake manafold area-- not into the airfilter. the engines area where the lower engines cases connect to the cylnder. just quick, light squirts. I always have a few cans of this cleaner here--- in the usa, go to wal-mart- the automotive area. look for CRC electronic cleaner. red can. This is methanol. harmless to plastics. It will cause the engines rpm-s to change if theres a aair leak. agan, its just a easy way to check for air leaks with out harming plastics or making a oily mess. pardon the spelling mistakes here-- its 6am, not yet up to my target heart rate with coffee yet!! lol.

 

[Skywatch]

Bet ice is right. I do not have the speakers hooked up here on the p-c. If after venting the gas cap- you still have the problem, If you have a aersol can of electronic cleaner laying around, when the engine is running, spray little squirts out of the red tube on the can around the carbs intake gasket- intake manafold area-- not into the airfilter. the engines area where the lower engines cases connect to the cylnder. just quick, light squirts. I always have a few cans of this cleaner here--- in the usa, go to wal-mart- the automotive area. look for CRC electronic cleaner. red can. This is methanol. harmless to plastics. It will cause the engines rpm-s to change if theres a aair leak. agan, its just a easy way to check for air leaks with out harming plastics or making a oily mess. pardon the spelling mistakes here-- its 6am, not yet up to my target heart rate with coffee yet!! lol.

Thank you will try this surely.