Trucks Traxxas 3.3 carb

[Wmcmillen]

I have a 3.3 that I have been able to get to sputter to life for a minute or so. It will run ok till it gets warm to the touch, then it will only run with the starter pack on the truck. I have change the glo plug to a new one and reset the carb to the factory setting. Even after all of this it will only run for a minute or so. I am using new fuel I recent purchased from a local HS. Any help would be great. Thanks

 

[Diederik]

Try to adjust your high speed needle 1/8th of a clockwise (turn it out) to richen it up until it runs properly IOW it does not splutter at top speeds if it does then just go back a 1/8th turn, then you need to start adjusting your low speed needle to get the low end correct. lastly you have to adjust your idling and then recheck every thing, also a lot of smoke = to rich, little or no smoke = to lean, just a thin trailing smoke is all you should have

Easiest, let the engine warm up, try and run a few circles and let it idle, it should idle evenly for a solid 1 minute, if the idling goes up it is to lean and vice versa. that you nrrd to adjust with your high speed needle

There are also a lot of You tube videos on how to tune correctly, but I am almost sure you are running to lean

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Try to adjust your high speed needle 1/8th of a clockwise (turn it out) to richen it up until it runs properly IOW it does not splutter at top speeds if it does then just go back a 1/8th turn, then you need to start adjusting your low speed needle to get the low end correct. lastly you have to adjust your idling and then recheck every thing, also a lot of smoke = to rich, little or no smoke = to lean, just a thin trailing smoke is all you should have

Easiest, let the engine warm up, try and run a few circles and let it idle, it should idle evenly for a solid 1 minute, if the idling goes up it is to lean and vice versa. that you nrrd to adjust with your high speed needle

There are also a lot of You tube videos on how to tune correctly, but I am almost sure you are running to lean

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Also, which percentage fuel are you using, you should use 20% although 25% will be fine as well

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Check out this vid, its a good one Nitro RC Engine Tuning Guide and Diagnostics_ By Squirrel.

I do not have the actual link

 

[Tony]

What is your compression like? If you don't get a good POP when you spin the engine over, then you need to replace your piston and sleeve.

 

[Wmcmillen]

I get a pop when I spin the engine over. It's not a strong as what some of your videos show though. I figured that was since the engine has a little run time on it, and the one in the video was just rebuilt.

 

[Tony]

Actually, the one in the video was only cleaned. I never replaced the piston or sleeve in that engine. Just got lucky. Even it was a little low on compression but still ran. The guy that purchased it (Adam here on the forum) just recently replaced the piston and sleeve after a couple gallons of fuel and runnign it hard.

If it still has a pop when you spin it over, then that should be good. I would take the carb off and clean it out really good, replace the fuel line and make sure the filter in the tank is not clogged. When you do get it running for a bit, look at the fuel line and see if you see any air bubbles. If you do, then there is a pin hole somewhere.

Also, remember that when the engine heats up, things expand. The piston should expand more than the sleeve (aluminum vs steel) but you will still lose compression as it heats up. It might be worthwhile if the fuel line and carb clean-out don't help to replace the piston and sleeve. Wish I could put my hands on it to verify.

I know you said you replaced the glow plug, but try putting a new one in it and try again. I have purchased glow plugs that were bad from day one.

 

[Island Breeze]

+1 for tony and diederik. its a process of ilimination. Work on Tony's method first and if all is good then move on to diederik method. I say put low and high ends to factory settings and tune from there. also note that once you are done running your truck for the day turn your motor by hand and make sure the piston is at the lowest point and not at TDC. this will give your piston longer life span.