Whats Wrong?
 

Hi, I'm having some problems with my engine. I don't know if this is normal for every truck or not but when I'm tuning the engine this is what happens: When I set the HSN to run rich it does....but then when I start to drive it its like it leans itself out...Ill give it full throttle then ill stop (its running rich but thats alright) I do the same thing right after I stop full again then stop and so on...and after I do this about 4-6 times the engine is running so lean on the last time I give it full throttle its crazy. Then after I'm done doing that and I let it sit (running) I can do the whole process over. It starts out rich again and then becomes lean. Can someone help me out plz..Could this be an air leak or is it just normal...I know my buddies truck doesn't do that.

Thanks for the help guyz and gals

RE: Whats Wrong?
 

All I know is that this is definitly not normal! Set both the high speed needle and low speed needle to the factory spec and if it still does the same I would think it is an air leak either in the fuel system or a carb seal. I had a similar problem with a new .15 Associated engine and I just sent it back to the factory and they sent me a new one!:D Other than that I cant think of any other problem that would make it lean out.

RE: Whats Wrong?
 

Well it definitely sounds like the HSN is loose and the vibrations from teh Engine are causing it to turn (in this case.. CClockwise)

Check to see if the O ring in the HSN is worn out.. that may be it.

Ram

RE: Whats Wrong?
 

Definitely the O-ring!

RE: Whats Wrong?
 

your low end may be lean.

RE: Whats Wrong?
 

Since it happens when you throttle it, but restarts after you let it sit, it sounds like a heat related leak or lean condition. Try tightening your head and carb, and check the HSN gasket just to make sure. Then if all else fails, send the engine back to the manufacturer.

RE: Whats Wrong?
 

Check for leaks. Definitly a leak.

RE: Whats Wrong?
 

I know it isn't the head, because I just put a whole new one on a couple of days ago, and I know my low end needle isn't lean. Could it be that there is a hole in the fuel line that is leading from the muffler to the gas tank? To check the O ring on the HSN how do I do that? (I have a TRX)

THANKS

RE: Whats Wrong?
 

I would still check the head. did you make sure the gasket(s) where moved to the new head? It could be a hole in your line coming from the tank to the engine. A hole from the muffler to the tank would cause a slight rise in idle speed due to reduced fuel line pressure. And to check your o ring on the high speed needle, you need to remove the needle by turning it counter clockwise until it wont back out any more. Then grab it with your finger or pliers and pull it out. Check the o ring for wear, is it stretched, cracked, missing? You could just replace it to make sure, O rings are like ten cents a piece. Hope this helps.

RE: Whats Wrong?
 

One question. Do you know what you are doing? If so I would send it to the manufacturer, but that is just me. I would only do that unless you know what you are doing. but then again, there is a first time for everything.

if you figure out where the leak is, I will give you step by step instructions on how to fix it.

RE: Whats Wrong?
 

hi all. just wondering if the muffler pressure is coming in to high and sending more air to the carb to make it run lean..not sure if this helps. i had to add about 4 inchs to my pressure line to get my rusty to stop going lean...:D

RE: Whats Wrong?
 

I checked the head and the Gaskets are there, the HSN O-ring looks fine, the carb is nice and tight, and the exhaust I tightened, the only things left that I could possibly take a look at is to see if the backplate is on tight and if there is a hole in the fuel line. How can I send it back to traxxas, its already broken in and what do I tell them...there isn't quite something right now fix it? Anyways I would like to try to fix my own problems rather than wait 5 weeks for my engine to get back home if I did ship it out there.


Thanks for the help I really do appreciate it

RE: Whats Wrong?
 

To send it back you need to call them first. They will tell you proper procedure or they may be able to tell you what is wrong. It kinda sucks that it will so long to get your engine back. but they may be sending you a new engine back, so it could be worth the wait. And as far as what to tell them, just give them the full run down on what its doing. Good luck.