Tmaxx 3.3 high engine idle.

[vtrang]

I got a used tmaxx on ebay and just replaced the carb on it. But now it's idling way too high. I adjusted all the needles to factory but the engine won't even start unless I trim open the idle and then will cut off when I set it back to 0. I have HSN and 4 turns out from bottom end, LSN flush and about 1 mm gap for the idle. All the fuel lines and tank are good and I don't see any holes or leaks from the exhaust pipe. Any ideas?

 

[tudordewolf]

You want to set the gap on the carb so that the engine keeps running, not to any particular gap. Once it's holding an idle you can tune it down

 

[CertifiedMike]

When you installed the carb did yu use anything to lube the orings that seal it? AE green slime is what you want to use. Pushing the carb on dry will twist those orings all up, no seal.
Are you positive that the carb you installed is good?
Your problem sounds like an air leak to me.
I'd be checking orings and the carb seal itself if tuning isn't working.

 

[vtrang]

I put some white lithium grease to help slide the carb in but honestly with the way the engine refuses to idle no matter what I do it seems like an internal engine air leak to me.

 

[CertifiedMike]

It might be an internal leak. I would be very careful to inspect ALL your orings for cracks or damage.
Lithium grease has petroleum base. Thats no good for rubber and plastic.
Use a silicone based lube on your rings or they will deteriorate and fail.
Is the carb you installed brand new? There are seals inside the carb too.
Why did you replace the carb? What was wrong?

The linkages all work correctly, smoothly? No chance something got bent during install?

Is the replacement also a factory 3.3 Traxxas carb? Identical to original?

An internal air leak is fixable too. I would just do as much on that carb as possible first.

If it ran until the carb swap, seems like a new problem would be coming from the new parts.

 

[vtrang]

I used carb cleaner on the old carb to get all the gunk out of it but the carb cleaner ended up eating away at the threads where the high speed needle screws in and I had to get a replacement. The replacement is not oem but an aftermarket replacement. Nothing wrong with the linkages as far as I can tell. Maybe I just need to replace the o-ring.

It might be an internal leak. I would be very careful to inspect ALL your orings for cracks or damage.
Lithium grease has petroleum base. Thats no good for rubber and plastic.
Use a silicone based lube on your rings or they will deteriorate and fail.
Is the carb you installed brand new? There are seals inside the carb too.
Why did you replace the carb? What was wrong?

The linkages all work correctly, smoothly? No chance something got bent during install?

Is the replacement also a factory 3.3 Traxxas carb? Identical to original?

An internal air leak is fixable too. I would just do as much on that carb as possible first.

If it ran until the carb swap, seems like a new problem would be coming from the new parts.

 

[CertifiedMike]

Never use that. Now you know why.
Any chance you have a link to the carb you bought?

I'd buy new orings, pull everything apart, use naptha to clean if you need to. Get all that white lube out and start fresh.

 

[vtrang]

If you type in "traxxas 3.3 carburetor" on the Amazon search bar it's the first one that shows up. The brand is Motoall. At this point I probably need a second replacement.

 

[vtrang]

Also, would silicone lubricant also work for the oring?

 

[CertifiedMike]

I don't know anything about those carbs. An OS carb is the recommended upgrade. I would buy the OS before amazon.
@Chubaka knows these motors well. Maybe he's seen one of these carbs.
Just be sure its petroleum free and you should be ok with silicone lube. Just make sure its slippy!

 

[vtrang]

Hey Mike

I just wanted to say thanks I used silicone lube and some new o rings and the engine fired right up and is idling perfectly. I have pretty much everything buttoned up on the truck now but the last thing I can't figure out is how the exhaust pipe mounts to that hanger bracket. I can't find any youtube videos or anything on it. Do you know how to remount it?

 

[CertifiedMike]

Hey Mike

I just wanted to say thanks I used silicone lube and some new o rings and the engine fired right up and is idling perfectly. I have pretty much everything buttoned up on the truck now but the last thing I can't figure out is how the exhaust pipe mounts to that hanger bracket. I can't find any youtube videos or anything on it. Do you know how to remount it?

Congrats! Excellent job! I'm glad it was inexpensive too!
I don't own the Tmaxx but I have a Jato and Revo, both 3.3.

There is a little set screw that holds the muffler to the hanger. Is this the issue?