T-Maxx 2.5 runs good then cuts out for no reason... Wont start after that... HELP!!!!

[Burns]

:flamer: Somebody please help... I've had my T-Maxx 2.5 now for 3 weeks and it runs fine for approx 5 minutes, then cuts out for no reason when I decellerate. Starting it afterwards, if I'm lucky will probably drain a fully charged started pack battery... I haven't got a temp guage, but it seems fine...
My thinking is the problem might be with my Low speed needle adjustment... can this cause it, and if so why??

I have not been able to finish one tank of fuel at a time without the motor cutting out at least 3 times. Any suggestions please please please... Desperate to join the "T-Maxx fun club" and not the frustrated operators corner...

 

[FastEddy]

First things first.
Check all the linkage including the settings when you use the brake. Sometimes when using the brakes the linkage and idle settings will cause the carburetor to close and the engine will cut out.

Once this is done retune your engines starting from the factory settings. This is an important issue when trying to get it running properly.

Here is a ling that will walk you through everything.
Traxxas How to Tune your 2.5

You may want to do a search on the subject for more in depth info but start with the link above.

-Ed

 

[SuperMaxx97]

my friend had the same problems with his 2.5, u have to take and put the settings back to the factory first just like eddy said. then from there just kinda mess with them a little bit. just dont do them both at the same time. start with the lsn and they work to the hsn.

bryan

 

[Burns]

Tried it all....

Thanks guys... I've checked my carburetor with the filter off and it opens properly, closes to about a 1.2mm gap (idling screw 1 & 1/4 turns out) when the brakes are fully applied. I have been back and forth from factory settings numerous times and either I cannot find the sweet spot or somethin else is wrong.

After running for about 3-5 mins it cuts out, mostly during a slowish turn or just easing off the throttle a little bit. I have full throttle control on the linkage though.. no problems there with the travel and sensitivity...

I struggle my @ss off to start it immediately afterwards, but giving it 5 mins to cool down it starts allmost immediately. This puzzles me as the engine has been run as rich to the point of wasting fuel, but it still does it.. I cannot imagine that at such a setting the engine can still overheat in such short time. My body is properly ventilated and it does it even without the body.

 

[SuperMaxx97]

is it running hot??? U NEED TO GET A TEMP GAUGE, but for now next time u are running it and after it dies, take a little bit of ur "spit" and put it on the engine head. if it sizzles that means that it is way too hot. if not u will be alright.

bryan

 

[Burns]

Heat hmmmm

I have done that on one or two occasions after cutting out and yes it sizzled... Maybe it was running too lean at that stage, but what could the implications be if it overheated. Would it cause the motor to overheat easier afterwards even running it much richer?

 

[SuperMaxx97]

when u run it richer it makes the engine run cooler. so if i was u i would take and richen it a hair. when ur engine gets too hot it will die after a few mins and then it is almost impossible to get it started until it kools all the way down again. so when u run it go and richen it a little bit and see if that helps u out any.

bryan

 

[Burns]

Will try that... It's just such a b!tch trying to set it up properly when it only runs for 3-5 mins at a time... Tell me generally do you guys run and finish a full tank... refuel and carry on without any hick-ups

 

[SuperMaxx97]

i will usually just run 1 tank at a time. most of the time it works really good, but then there are the days that it just seems that it doesn't want to run. personally i dont liek to run it more than 1 take at a time without letting it rest. dont know why just something that i do.

bryan

 

[Burns]

Air bubbles in fuel tank

Somethin else I'd like to ask... I have noticed while getting some revs on the motor, the fuel tank is making loads of air bubbles... is this normal

 

[SuperMaxx97]

are the air bubbles going through the gas tubes? cause if they are then u have an air leak. in that case change all of ur tubing, and check ur carb to make sure it isnt leaking. also is ur gas take a priming one or one without it?

bryan

 

[slim]

hello Burns,a bunch of us get together and run our trucks on the weekends and the Tmaxx's all seemed to have the same problems,a couple of us changed from the stock fuel tank to a tank for the Ofna 9.5 buggy.The receiver has to be placed where the stock tank goes so the ofna tank can be mounted in its place on the right front corner of chassis,the results were tuning issues gone,air bubbles gone,overheating and stalling gone,the stock tank has no baffling in it causing the fuel to move away from the pickup,causing foaming and air in the fuel line,so far 5 of us have done the mod and all with same results,cooler running,no mess tuning,longer run times,give it a try. take care.

 

[Mondo]

Bubbles

Slim,

Great tip indeed. Ironically enough my T-MAXX 2.5 was giving the same crap when it still had the TRX 2.5 motor in it - that's been replaced with a Sirio TX 18 that hasn't been run yet.

I couldn't quite get it worked out either. It seems as if your cure is the most logical explaination to this problem.

A few questions for you Slim:

What capacity is the Ofna tank? 75cc, 125cc or larger?
Any chance of the Ofna part number?
Could you please Post a picture of this conversion?

Thanks

 

[funwheels1]

MAN! I had The SAME SAME SAME exact problem.....when i say this dont hate me poeople its not my forum but I'm trying to help a MAXX in need. Well, i have a savage and I'm pretty well known for its problems Anyways, I couldnt get it to run for more than 5 min or a 1/4 of a tank....Let me tell u i got pretty pissed after paying about 450 dolars for something that didnt run after break in.....Let me tell u what i did. After running it i noticed air bubbles......BIG BUBBLES. I went out and bought a Spritz made by armoral. I put one in a quart of 20% NItro thunder and it solved that problem. I got the spritz idea from Skymaxx and it worked great for me......Also...LEANING MY engine made it run so long....I leaned it wayyyyyy to much and it ran for bout 7 min and the carb started boiling ur fuel.......I mean...if i run mine rich it dont run worth poop but if i lean it its the bomb...however this was on a sunstar .21 bb engine not a trx Good luck.

Drew:fro:

 

[Burns]

PROBLEM SORTED

Thanks guys for all the help.... Finally sorted it out and it was not any of the above problems although every one of them seemed feasable in my situation...

After numerous calls to Traxxas and a huge fight with my Traxxas supplier, the motor was taken apart and it was found that the piston had a factory fault, causing more friction, obviously making it run much hotter... causing the cut-outs...

My T-Maxx has a brand new piston and sleeve set fitted and I ran it in for 10 tanks as rich as the car would run... making sure it's properly lubricated for the run-in... After that the normal Traxxas 5 tanks run-in was done and tuned....

IT FLIES!!!!!
THANKS TO ALL THOSE WHO PARTICIPATED IN HELPING ME OUT... YOU GUYS CAN SEND THE BILL :whistle: lol

 

[808_maxx]

Hey what kind of spritz is this??? And also the part number for the ofna tank. thanks

 

[JC Sportmaxx]

I feel your pain...

I have a sportmaxx I got brand new back in april. It always done the same thing, about two weeks ago, I was running my truck and a buddy of mine brought over his temp gun. He told me to run it until it dies and then let him take the temp. it was running WAY to hot!!! so we kept richening the HSN until it got to about 260 degres. that made it run mutch better, but it would still die after a few minuites and would not start back until it cooled off. So I decided to tinker a little with the hsn, I barely turned the screw counter clockwise, I mean I turned it so little that you could'nt really tell it by looking at the screw. Anyways, now the truck runs perfect!!!!:thumbup: I ran 6 tanks of fuel through it non-stop! Remember, the SMALLEST adjustment of the hsn and lsn screws can make a HUGE difference!:LoL:

Hope this helps.
JC Sportmaxx

 

[Baltimore RC]

PROBLEM SORTED

Thanks guys for all the help.... Finally sorted it out and it was not any of the above problems although every one of them seemed feasable in my situation...

After numerous calls to Traxxas and a huge fight with my Traxxas supplier, the motor was taken apart and it was found that the piston had a factory fault, causing more friction, obviously making it run much hotter... causing the cut-outs...

My T-Maxx has a brand new piston and sleeve set fitted and I ran it in for 10 tanks as rich as the car would run... making sure it's properly lubricated for the run-in... After that the normal Traxxas 5 tanks run-in was done and tuned....

IT FLIES!!!!!
THANKS TO ALL THOSE WHO PARTICIPATED IN HELPING ME OUT... YOU GUYS CAN SEND THE BILL :whistle: lol

So how did you get traxxas to comply? I'm having this same problem now but traxxas is blaming it on me when it was frigging brand new! I know I'm 20 years late but if you can help me in any ways here my number 443 415 9104