T Maxx 2.5 starting issue

[madd802]

i dont know what else to do so i just gave up. i had it started five or six times and it was blowing smoke like its supposed to. i tried leaning it and richening it but it either starts and does that crazy mega rev thing and goes full throttle or either it doesn't start. i have adjusted the hsp and low and idle so i dont know

check the throttle trim on your remote. also check the batteries in remote and on truck

 

[Sethhh!]

steering and throttle were both on 0. it could be something else wrong. again, the truck hasnt been run in probably five years and who knows why it stopped running back then. and all batteries were new. i just put them in the other day

 

[Rolex]

motor works fine. its NOT flooded. owb is lubed and right direction. ez start DOES roll the engine, just wont start.

only other thing i know to do is take it to the local shop and let them check it out..?

DON'T take it to the shop.
I just checked this thread, and you've been everywhere except in the right place.
The engine spins and sputters. No reason to bang on the starter motor since it's working.
The engine spins and sputters. No reason to be worried about after run oil.
No reason to be worried about hydro lock if you didn't need the ARO to begin with. ARO is for storing, not starting.
Where the transmission is just doesn't matter with starting. The only thing that matters with the servos is if they are working correctly and in the right plug of the rx.

I don't know if you've primed the engine by putting your finger over the exhaust while spinning the starter, but that might be your issue.
Before starting ANY nitro vehicle make sure your throttle servo opens and closes EXACTLY as it should. Starting with it half open can result in a runaway or tire burns on your arm.

To eliminate ALL your problems, take off the air cleaner and put a little fuel directly into the carb and start the engine. If it starts, runs a few seconds and then stalls, you've got a clogged needle valve or just old, bad fuel.

 

[Sethhh!]

well i can tell you right now its not old bad fuel because i bought it from a lhs last week lol and none of that stuff is a problem. everything is working just fine. I'm pretty sure it has to do with my tuning or something with the carb. and i always prime it first. however the throttle servo is another thing. i have had a lot of troubles with the carb closing back. but i fixed the carb return. i did fail to check the throttle servo first though. but before you go on about that, let me say this. i HAVE taken the horn off and let it set or whatever you call it and put the horn back on. seeing pictures and it being this way when i took it apart and everything, i assumed that the horn is supposed to be placed on there straight with the T shape upright. correct me if I'm wrong though

---------- Post added at 6:27 PM ---------- Previous post was at 6:25 PM ----------

and is the needle valve the piece coming in on the inside of the carb that lets the fuel through..? i very well could have a clogged needle, but that wouldnt cause the truck to go full throttle as soon as it starts though would it..?

 

[Rolex]

You had the high rpm issue because you didn't check the throttle position before starting it.
Now you might be dealing with a bit of old fuel snot that dislodged from the line or the carb input nipple.
Again, fuel directly into the carb and try starting it immediately. You can't let it sit in there and then go eat dinner because the rapid evaporation would just leave you with oil.

 

[Sethhh!]

so how am i to go about checking the throttle position? i mean obviously it doesn't need to be way off to one side. but have it centered..?

 

[Rolex]

Right now we want to see if it will start in order to eliminate other problems.
Just put fuel in the carb, put on the ignitor, spin the ez-start.
If it runs more than 3 or 4 seconds you can stop it by putting your finger on the carb.

 

[Sethhh!]

it will already start. it just wont stay running after a couple seconds. but if i pick it up and let the wheels go wild it will keep going building higher and higher even after i turn the truck and radio off. i have to pinch the line to get it to quit

 

[Rolex]

Take off the air cleaner so you can see the slide. Some rotate, some slide. Set the trim knob all the way down. NOT to zero if that's in the middle, but ALL THE WAY DOWN.
With the Tx and Rx on, trigger the throttle/brake and observe the movement. What happens if you just let go of the trigger without pushing the brake?
Does the slide close completely with the brake applied, is it slightly open or still half open?

 

[Sethhh!]

with the trim all the way down, it doesn't move it at all, with it at 0 it does half and at max, it open all the way

 

[Rolex]

Disconnect the servo arm. Work the servo with the throttle trigger. What does it do.
While it's still disconnected, work the throttle linkage by hand. Full open, fully closed. What does it do?
When it's fully closed, how much of an opening do you see?

 

[Sethhh!]

servo arm..? horn or linkage? fully closed theres like 1-1.5mm maybe but thats because the little piece that sticks out inside there. and i will throw in there that one of the servos makes a buzz sound. none of them twitch anymore, but i think its the shift or throttle servo. it sounds like its straining with how it constantly buzzes but that may be normal and I'm not used to it

 

[Rolex]

This is what you should see.

If that's what you have when it's closed as far as it can go, it's good. If it closes with the brake, it's not good.

The servo arm is also called the horn. Did you take it off and work the linkage by hand?

 

[Sethhh!]

alright. with the trim set to 0 it closes to look like that picture and again, it only opens about halfway. the linking and return all work right. as far as i can tell anyways

 

[Rolex]

Is it opening half way by hand or with the radio?

 

[Sethhh!]

with the radio. by hand it will open all the way. before, the piece holding the carb linkage or whatever on was getting caught on the front piece of the ez start so i shaved a little bit of it off and now it slides smooth and returns decently

 

[Rolex]

What kind of radio are you using? If it's a computer radio you can set the end points. If it's not, you need to find the problem mechanically.
With the linkage disconnected and the servo arm (horn) still on the servo, use the radio and move the trigger to determine if the servo moves the same distance in each direction. Full throttle, full brake.
If it does, take off the arm, reconnect it to the linkage and install it on the servo with the trim off and the carb slide in the idle position.

 

[Sethhh!]

its the original traxxas one that comes with it. it goes farther for throttle than brake. i dont think it completely closes back. its pretty close though

 

[Rolex]

Connect it so you get a full throw for the throttle and a full throw for the brake. If the servo strains to go farther in either direction you either have to put the linkage in a different hole in the horn or make mechanical adjustments.

 

[Sethhh!]

how does this affect the crazy rpm..?