2LikesOld T-Maxx 3.3 issue.
12-04-2017, 03:42 PM
#1
Old T-Maxx 3.3 issue.
Hey guys, so coming here as a last resortish kinda thread. I have had my T-Maxx for around 6-7 years now and recently have got here back up and running. Now, she'll start when she wants, but won't hold. Just today I installed a pull-start and got rid of that ez-start bull shit hoping that would fix my problems, thinking the wire to the glow plug wasn't getting currents. Got everything good, went to go start here up and eventually got here going after 30-40 pulls. She is unable to hold an idle, immediately starts to move forward (considered it a tuning issue, but coming to think it may be something more after much nitpicking around with her). So, came here looking for maybe some insight on why she is SO hard to get started and then keep going. I prime the engine every time and I've also heated the engine before starting, with no luck. Any ideas what could be causing the such time consuming and irritating start up? I mean once she gets going, she goes. But just can't hold an idle nor start without tons of pulling.
12-04-2017, 04:01 PM
#2
Tech Apprentice
First I would take apart and rebuild the engine, if it has been sitting for that long it probably needs a rebuild, check compression and for any rust, use a super-high grit sandpaper to get it off, I think traxxas said 1200 grit, here's the official post https://traxxas.com/support/TRX-Engine-Rebuild-Instructions-0"Remove this and the quotes"
I'm not allowed to post URL's yet, remove the quotes and stuff after the "0"
After that I would set the carb back to factory spec, maybe lean it out a tiny bit since it's already been broken in, also, sounds like you idles to high, find a large paper clip, they are exactly 1mm, but that in a carb and set it to have a 1mm opening, maybe a tiny bit less.
If that does not work, take your transmission apart, does yours have reverse, if so I would remove it, it's only $12 ish and greatly improves the performance, also check your spur gear mesh.
One last thing, use new fuel, if you are already that's fine, the methanol in the fuel sucks up water in the air and decreases performance and does get "weaker" over time. So always put your fuel cap back on
I'm not allowed to post URL's yet, remove the quotes and stuff after the "0"
After that I would set the carb back to factory spec, maybe lean it out a tiny bit since it's already been broken in, also, sounds like you idles to high, find a large paper clip, they are exactly 1mm, but that in a carb and set it to have a 1mm opening, maybe a tiny bit less.
If that does not work, take your transmission apart, does yours have reverse, if so I would remove it, it's only $12 ish and greatly improves the performance, also check your spur gear mesh.
One last thing, use new fuel, if you are already that's fine, the methanol in the fuel sucks up water in the air and decreases performance and does get "weaker" over time. So always put your fuel cap back on
12-04-2017, 09:07 PM
#3
First I would take apart and rebuild the engine, if it has been sitting for that long it probably needs a rebuild, check compression and for any rust, use a super-high grit sandpaper to get it off, I think traxxas said 1200 grit, here's the official post https://traxxas.com/support/TRX-Engine-Rebuild-Instructions-0"Remove this and the quotes"
I'm not allowed to post URL's yet, remove the quotes and stuff after the "0"
After that I would set the carb back to factory spec, maybe lean it out a tiny bit since it's already been broken in, also, sounds like you idles to high, find a large paper clip, they are exactly 1mm, but that in a carb and set it to have a 1mm opening, maybe a tiny bit less.
If that does not work, take your transmission apart, does yours have reverse, if so I would remove it, it's only $12 ish and greatly improves the performance, also check your spur gear mesh.
One last thing, use new fuel, if you are already that's fine, the methanol in the fuel sucks up water in the air and decreases performance and does get "weaker" over time. So always put your fuel cap back on
I'm not allowed to post URL's yet, remove the quotes and stuff after the "0"
After that I would set the carb back to factory spec, maybe lean it out a tiny bit since it's already been broken in, also, sounds like you idles to high, find a large paper clip, they are exactly 1mm, but that in a carb and set it to have a 1mm opening, maybe a tiny bit less.
If that does not work, take your transmission apart, does yours have reverse, if so I would remove it, it's only $12 ish and greatly improves the performance, also check your spur gear mesh.
One last thing, use new fuel, if you are already that's fine, the methanol in the fuel sucks up water in the air and decreases performance and does get "weaker" over time. So always put your fuel cap back on
12-05-2017, 06:32 AM
#4
Tech Apprentice
Ok, unless you have not put 7+ gallons of fuel through it the sleeve and piston should be fine, only thing I can say now is rebuild the engine, reset carb, and check the bearings, they should not feel grainy at all, or when everything else is out of the engine, put the crank in, then try to wiggle the crank up-down by the output and if it moves, replace the bearings.
12-05-2017, 06:58 AM
#5
I would add new fuel tubing as well. Along with engine and carb rebuild. New plug. How old is the fuel?
12-05-2017, 05:38 PM
#7
1. Not idling and moving forward while idling are symptoms of a broken clutch spring.
2. Replace the glow plug
3. Use fresh fuel
4. Set carb idle gap to .5-.6mm and blow through fuel line to carb at idle. Air should barely get through. Open carb wide open and blow again. Air should move through easily. If air doesn’t move easily, open needles 1/2-1 turn and try again. If no joy, remove the carb from the engine, disassemble, clean with acetone, and reassemble.
5. Check bearings for grittiness. If crank turns smooth, bearings should be good. If crank turns rough, replace bearings.
6. If you get it primed right, glow driver is fully charged, and glow plug is new/known good, it should start and run within 4-6 pulls easily. My 3.3s start in 2 pulls religiously - one has 4 gallons on it and the other has over 8 gallons on it.
2. Replace the glow plug
3. Use fresh fuel
4. Set carb idle gap to .5-.6mm and blow through fuel line to carb at idle. Air should barely get through. Open carb wide open and blow again. Air should move through easily. If air doesn’t move easily, open needles 1/2-1 turn and try again. If no joy, remove the carb from the engine, disassemble, clean with acetone, and reassemble.
5. Check bearings for grittiness. If crank turns smooth, bearings should be good. If crank turns rough, replace bearings.
6. If you get it primed right, glow driver is fully charged, and glow plug is new/known good, it should start and run within 4-6 pulls easily. My 3.3s start in 2 pulls religiously - one has 4 gallons on it and the other has over 8 gallons on it.
12-05-2017, 06:30 PM
#8
1. Not idling and moving forward while idling are symptoms of a broken clutch spring.
2. Replace the glow plug
3. Use fresh fuel
4. Set carb idle gap to .5-.6mm and blow through fuel line to carb at idle. Air should barely get through. Open carb wide open and blow again. Air should move through easily. If air doesn’t move easily, open needles 1/2-1 turn and try again. If no joy, remove the carb from the engine, disassemble, clean with acetone, and reassemble.
5. Check bearings for grittiness. If crank turns smooth, bearings should be good. If crank turns rough, replace bearings.
6. If you get it primed right, glow driver is fully charged, and glow plug is new/known good, it should start and run within 4-6 pulls easily. My 3.3s start in 2 pulls religiously - one has 4 gallons on it and the other has over 8 gallons on it.
2. Replace the glow plug
3. Use fresh fuel
4. Set carb idle gap to .5-.6mm and blow through fuel line to carb at idle. Air should barely get through. Open carb wide open and blow again. Air should move through easily. If air doesn’t move easily, open needles 1/2-1 turn and try again. If no joy, remove the carb from the engine, disassemble, clean with acetone, and reassemble.
5. Check bearings for grittiness. If crank turns smooth, bearings should be good. If crank turns rough, replace bearings.
6. If you get it primed right, glow driver is fully charged, and glow plug is new/known good, it should start and run within 4-6 pulls easily. My 3.3s start in 2 pulls religiously - one has 4 gallons on it and the other has over 8 gallons on it.
12-05-2017, 10:18 PM
#9
If the clutch checks out, check the throttle linkage and carb slide idle gap. Make sure that the gap is .5-.6mm and the linkage is returning it to idle without having to hit the brakes to close it to the idle stop and also ensure it’s working freely and not hanging up anywhere.
12-08-2017, 08:34 PM
#10
It’s common sense. If the engine isn’t revving up much if at all or won’t hold an idle but moves forward, it’s pretty obvious to someone experienced that checking the clutch is th first thing to do. When the first responses are to rebuild the engine and check for rust (and sand it off with sandpaper); be wary of what advice you take out of the gate.
If the clutch checks out, check the throttle linkage and carb slide idle gap. Make sure that the gap is .5-.6mm and the linkage is returning it to idle without having to hit the brakes to close it to the idle stop and also ensure it’s working freely and not hanging up anywhere.
If the clutch checks out, check the throttle linkage and carb slide idle gap. Make sure that the gap is .5-.6mm and the linkage is returning it to idle without having to hit the brakes to close it to the idle stop and also ensure it’s working freely and not hanging up anywhere.
12-08-2017, 09:37 PM
#11
Tackle the other things on the list I gave. Jumping right to rebuilding the engine may prove more costly than is necessary and may not fix the problem.
12-09-2017, 12:40 PM
#12
Sorry, yes checked everything with throttle linkage and carb. Even took off the cleaned it and sprayed it with WD40 to make sure it would open and close freely. Quite confused on this engine, can't think of what the issue could be. I am going to just get new clutch slippers today, because supposely they should form a complete circle. Mine seem barely worn down, but gonna replace them either way I guess gotta go to hobby store anyways. Anything else you can think of causing this issue? Also, when I tried starting it I just can't even get it started anymore. Never wants to pull fuel to the exhaust, so I always have to blow it through. I am going to clean out the exhaust tonight with cleaning foam and see if there is maybe built up dirt in it. Seems a bit dirt, so thinking there could be something blocking air flow, but I don't know. Thanks.
12-09-2017, 07:38 PM
#13
Keep the WD40 away from model engines. If you’re going to oil anything on an engine, use air tool oil, sewing machine oil/3-in-1 oil, or regular automotive transmission fluid. WD40 evaporated leaving virtually nothing behind.
As long as the muffler pressure fitting from the exhaust to the fuel tank is clear of obstruction, there’s nothing that needs to be done to it. Most tractability problems are related to the glow plug or the carburetor - whether it be improper needle settings and/or idle gap, or dirty fuel inlet/clogged fuel passages. The latter is rarely a problem.
I prime all of my engines by blowing into the pressure line from the muffler to the tank. Blow until fuel reaches the carb and go 1/2-1 second more. Reconnect the pressure line and start the engine. If your needle setting is too lean, it should fire up, run off the prime, and quit. Open idle needle 1/2 turn and try again. You can use the factory carb settings to get started, but if you do that, lean the main needle 1 turn in and 1/2 turn leaner on the idle mixture. Make sure the idle gap is no larger than .6mm to start and the throttle linkage is working properly and smoothly. Ensure the throttle is closing to the idle stop on its own with the throttle trigger in the neutral position. Ensure you have a little bit of throttle deadband in the linkage!!
As long as the muffler pressure fitting from the exhaust to the fuel tank is clear of obstruction, there’s nothing that needs to be done to it. Most tractability problems are related to the glow plug or the carburetor - whether it be improper needle settings and/or idle gap, or dirty fuel inlet/clogged fuel passages. The latter is rarely a problem.
I prime all of my engines by blowing into the pressure line from the muffler to the tank. Blow until fuel reaches the carb and go 1/2-1 second more. Reconnect the pressure line and start the engine. If your needle setting is too lean, it should fire up, run off the prime, and quit. Open idle needle 1/2 turn and try again. You can use the factory carb settings to get started, but if you do that, lean the main needle 1 turn in and 1/2 turn leaner on the idle mixture. Make sure the idle gap is no larger than .6mm to start and the throttle linkage is working properly and smoothly. Ensure the throttle is closing to the idle stop on its own with the throttle trigger in the neutral position. Ensure you have a little bit of throttle deadband in the linkage!!
12-09-2017, 07:48 PM
#14
Keep the WD40 away from model engines. If you’re going to oil anything on an engine, use air tool oil, sewing machine oil/3-in-1 oil, or regular automotive transmission fluid. WD40 evaporated leaving virtually nothing behind.
As long as the muffler pressure fitting from the exhaust to the fuel tank is clear of obstruction, there’s nothing that needs to be done to it. Most tractability problems are related to the glow plug or the carburetor - whether it be improper needle settings and/or idle gap, or dirty fuel inlet/clogged fuel passages. The latter is rarely a problem.
I prime all of my engines by blowing into the pressure line from the muffler to the tank. Blow until fuel reaches the carb and go 1/2-1 second more. Reconnect the pressure line and start the engine. If your needle setting is too lean, it should fire up, run off the prime, and quit. Open idle needle 1/2 turn and try again. You can use the factory carb settings to get started, but if you do that, lean the main needle 1 turn in and 1/2 turn leaner on the idle mixture. Make sure the idle gap is no larger than .6mm to start and the throttle linkage is working properly and smoothly. Ensure the throttle is closing to the idle stop on its own with the throttle trigger in the neutral position. Ensure you have a little bit of throttle deadband in the linkage!!
As long as the muffler pressure fitting from the exhaust to the fuel tank is clear of obstruction, there’s nothing that needs to be done to it. Most tractability problems are related to the glow plug or the carburetor - whether it be improper needle settings and/or idle gap, or dirty fuel inlet/clogged fuel passages. The latter is rarely a problem.
I prime all of my engines by blowing into the pressure line from the muffler to the tank. Blow until fuel reaches the carb and go 1/2-1 second more. Reconnect the pressure line and start the engine. If your needle setting is too lean, it should fire up, run off the prime, and quit. Open idle needle 1/2 turn and try again. You can use the factory carb settings to get started, but if you do that, lean the main needle 1 turn in and 1/2 turn leaner on the idle mixture. Make sure the idle gap is no larger than .6mm to start and the throttle linkage is working properly and smoothly. Ensure the throttle is closing to the idle stop on its own with the throttle trigger in the neutral position. Ensure you have a little bit of throttle deadband in the linkage!!
12-09-2017, 08:06 PM
#15
The idle gap adjustment is the screw that goes into the side of the carb at an angle. The idle mixture needle is in the end of the slide valve of the carb where the throttle linkage connects.