Stupid Tmaxx....Stupid TRX 3.3....

[Beddo]

But more likely.......stupid Beddo.

Firstly, sorry for the long post, but I feel I need to explain everything I've tried.

OK, so I've got a TRX 3.3 which I have run about 3/4 gallon through of 25% (1st Monster Juice but now Byrons). The motor used to start no problem, warm or cold, and whilst I have had some tuning issues in the past, since I got these sorted it has been running like a gem.

Then the main bearing gave up, so that was changed for a new one. The sleeve and piston were checked and are in excellent condition. Compression and pinch seem good. I took the opportunity to completely seal the engine and it was at this point I noticed that one of the holes in the carb body where the larger blank plug fits had stripped its threads. I ordered a new carb body and at the weekend built and sealed the motor again.

Now I can't for the life of me get the thing to fire up.

I'm running a roto start and it just turns over, and over again, never really looking like its gonna fire. I've tried priming by plugging the exhaust and watching fuel go into the carb. I've gently blown into the pressure pipe and watched fuel go into the pipe. The only time the motor looks like it may start is if I drop a small amount of fuel into the mouth of the carb, then it will chug a bit, like its about to start, then continue just turning over.

I've done a pressure test on the fuel lines by plugging the fuel line at the end that goes into the carb, and blowing into the pressure line off the exhaust, so I'm confident that the fuel system is air tight, as is the engine.

I've tried new plugs, new batteries in the glow starter and in the roto start (I've even used a 7 cell pack to try get a bit more spped from the roto start)

I'm at my wits end as I simply dont know what to try next. I'm considering doing a home pinch job on the liner, but I'm sure that its OK since the compression feels pretty good.

I wondered if there wasn't enough fuel getting into the cylinder, the top of the piston never seems to be very wet when I take the plug out. Also if I try to start without the filter on (not something I would normally do obviously) there seems to be plenty of fuel coming back out of the mouth of the carb, especially if I plug the exhaust port, almost as if the fuel isnt getting into the motor?

Any ideas or suggested would be greatly appreciated. I've ordered an )S .18TZ, but it wont be here for a couple of weeks and I'm lost without my Maxx

 

[hipluther01]

You may wanna check what the plug you rethreaded. It may have gotten a peice of plastic lodged in there and it stopping fuel from entering completely through the carb.

 

[blckrevo33]

did you take the piston and rod out of your engine? if you did you might have put it in bacwards. i did this when i rebuilt my 3.3 and it exactly what you are saying. i took it back apart and turned the rod 180 and put it back together and it is fine.basically the piston notches are intake and exhaust you probaly have it in backwards. hope this is of some help.

 

[olds97_lss]

Could also be the yellow grounding wire. If that doesn't have a good connection, I don't think it will heat the plug.

I only bring it up because you've had the engine off and it's usually bolted to the engine via the engine mount bolt.

 

[Beddo]

did you take the piston and rod out of your engine? if you did you might have put it in bacwards. i did this when i rebuilt my 3.3 and it exactly what you are saying. i took it back apart and turned the rod 180 and put it back together and it is fine.basically the piston notches are intake and exhaust you probaly have it in backwards. hope this is of some help.

I'm pretty sure the piston is in right, I remember checking to see that the oil hole in the rod was facing to the front of the engine.

Could also be the yellow grounding wire. If that doesn't have a good connection, I don't think it will heat the plug.

I might be wrong here, but if I'm using an external glow heater i.e. not the EZ start, I dont need the yellow wire. In fact, the wiring harness isnt installed at all.

 

[big jilm]

Have you tested the plugs by holding them in the igniter and watching them glow??? Maybe your igniter is bad...Only thing left would be some type of blokage I would think..

what are your needle settings and whats you idle gap look like???

 

[qaart]

it sounds like you just got a clog or no fire

 

[olds97_lss]

I might be wrong here, but if I'm using an external glow heater i.e. not the EZ start, I dont need the yellow wire. In fact, the wiring harness isnt installed at all.

Nope, your not wrong. I missed that in your post before.

 

[Beddo]

• Glow starter is good, tried a couple of different plugs, no worries there.
• I've checked the piston and its right, assuming that the cut out in the skirt should face the front i.e. the flywheel?
• I've done another leak test and found that there was a tiny leak from the carb pinch bolt. I dont think its significant, but I've sealed it up anyway.
• I've also done a leak test on the tank and thats fine - there's deffo no blockages anywhere.

I'm goosed with this one. I'll give it another try tonight once the silicone has gone off, but I'm not really hopeful tbh. I'll let you know.

 

[surgemaster1970]

Sounds ok .It can be verified here...scroll down to rebuilding procedures...maybe you need a new carb..

http://www.traxxas.com/PDF-Library/TRX33_manual.pdf

 

[destrucktomaxx]

When you rebuilt the carb body, did you inspect it for F.O.D? I know when I bought a carb body from Traxxas, there was plastic F.O.D in the high speed needle seat. I ended up having to carefully pick it out with tweezers. Also, is there a metal ring on top AND bottom of the H.S.N, between the fuel petcock? And last but not least, is the head on right? Lined up with the grooves in the head and block. Hope this helps, good luck buddy!

 

[Beddo]

Sounds ok .It can be verified here...scroll down to rebuilding procedures...maybe you need a new carb..

http://www.traxxas.com/PDF-Library/TRX33_manual.pdf

Sorry, I'm not sure what you mean? I have already fitted a new carb?

I will strip the carb again tonight and make sure there isnt any debris in there and report back tomorrow. Wish I wasn't at work so I could get in the garage now :\

 

[TMAXX]

I had a hard time starting my 3.3 and after cranking through 2 battery packs i tried a clip on glow starter. it fired right up. I then bent the positive tab(or whichever is facing up) on the ez start electric motor up and away from the spur gear. what i would do it prime the engine and let it crank a bit. then i would pull the positive wire off the electric motor and try to crank it to get the glow plug good and hot. i then just touched the positive wire to the electric motor for a second and it starts right up. this is a great trick.

 

[Beddo]

I had a hard time starting my 3.3 and after cranking through 2 battery packs i tried a clip on glow starter. it fired right up. I then bent the positive tab(or whichever is facing up) on the ez start electric motor up and away from the spur gear. what i would do it prime the engine and let it crank a bit. then i would pull the positive wire off the electric motor and try to crank it to get the glow plug good and hot. i then just touched the positive wire to the electric motor for a second and it starts right up. this is a great tricks.

I'm using a rotostart, as per the original post...... :\

 

[Beddo]

Still having massive problems.
Made a video at the weekend so that someone might be able to help.......

[ame=http://www.youtube.com/watch?v=rNIOvU6T6D4] Heres the vid, just check the sounds that the truck makes[/ame]

I've actually stripped the engine down again today since I really can't figure out what the problem is. I'm wondering if it might be the pinch.......basically, with pretty much no effort, the piston pushes a mm or so out the top of the sleeve

Think I'll try and do a home pinch job, what have I got to loose

 

[qaart]

it wants to start it sounds like

 

[olds97_lss]

Think I'll try and do a home pinch job, what have I got to loose

Yep. Needs pinch put back. Send it to Ray at www.rayaracing.com. $25 will save you the headache of a out of round pinched sleeve. Cheaper than new, lasts a good long while.

Any time you can push the piston easily that far up the sleeve, it's time for work or replacement. If there aren't any noticeable scratches in the sleeve or piston, then pinching it is definitely an option.

Considering the P/S for the 3.3 is $67 (more when shipped), it's probably better off to let someone do it who has the tools and experience.

Here's a thread for some I had done by Ray:
https://www.rcnitrotalk.com/forum/showthread.php?t=56420&highlight=rayaracing

EDIT:
Just watched your vid... your not from around these parts are ya . Not sure what shipping to Ray will cost from outside the States.

 

[Beddo]

Yep. Needs pinch put back. Send it to Ray at www.rayaracing.com. $25 will save you the headache of a out of round pinched sleeve. Cheaper than new, lasts a good long while.

EDIT:
Just watched your vid... your not from around these parts are ya . Not sure what shipping to Ray will cost from outside the States.

Haha, no, not from round those parts at all

I've already done the pinch anyway, warmed the sleeve up in a bearing oven at work then quenched it in some nice clean oil. The piston is nicely nipped about 3-4mm from the top of the sleeve now.

Gonna give it a go at lunch time.

 

[TMAXX]

There is a pincher for the 3.3 on ebay its like $20 shipped. I have the link if you need it.

 

[jasminemy4g63]

Definately needs a pinch if the piston pushes up flush with the sleeve or above it needs a pinch