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Old Oct 23, 2011, 10:07 AM
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why wont my trx .15 stay running

i have a nitro sport with a trx .15 pro and it will start and run great as long as i hond the ez start on for the glow plug. i start it, then take one of the starter wires off, and everything works as its supposed to, at any throttle position, but as soon as i turn the glow plug off, it dies, immediately, please help and thanks for everything.
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Old Oct 24, 2011, 08:10 PM
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Throttlejunkie's Avatar
Sydney, Australia
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Hi, have you tried a new glow plug.

Cheers
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Old Oct 25, 2011, 08:07 PM
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I had one do that and it was a massive air leak in the engine at the backplate.

Try a new plug first though.
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Old Oct 25, 2011, 09:33 PM
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If it runs great with the plug igniter, and stalls without it it's definitely the plug. If it's running very rich you could also have that happen, but you typically notice it's running rich even with the igniter on.
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Old Oct 27, 2011, 05:30 PM
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hey guys, i have the trx .15 in my older version of the Nitro Sport. It has good compression and runs great when it does actually start.

its been in storage for a year or so. the last two times i pulled it from storage and ended up putting it back in the box after getting fed up with starting problems.

i've been flying glow airplanes and have learned how to properly tune an engine...so i busted out the nitro sport to give it another go.

i put some 15% nitro 18% oil airplane fuel in the tank and within a couple minutes i had the engine started and was doing circuits in my backyard. took it out in the road and tuned the top end. man, it was running great till the tank was empty.

after that i couldn't start her again. fuel is getting there. glow plug is good. any ideas??
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Old Oct 27, 2011, 06:03 PM
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I tried 30/20 heli fuel too. It's like on the brink of starting but just won't.
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Old Oct 27, 2011, 09:00 PM
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i did some reading on old threads. some people say that a leak in the exhaust system will affect tank pressure...priming of engine. i think that may be my problem so i used red RTV sealant on the muffler joint. for good measure, I removed the carb and put a little red RTV on the mount to make sure there isn't an air leak there. i also put a little on the exhaust nipple threads.

i'll report back after everything dries.

tank and fuel lines all seem to be fine.
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Old Oct 27, 2011, 09:32 PM
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Is the engine getting a good prime? You might have to give it a bit of throttle trim (or have a friend hold the throttle open slightly) to get it started.
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Old Oct 28, 2011, 11:56 AM
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Quote:
Originally Posted by wparsons View Post
Is the engine getting a good prime? You might have to give it a bit of throttle trim (or have a friend hold the throttle open slightly) to get it started.
No, it isn't getting much fuel at all. With my thumb over the carb, it moves very slowly through the fuel line. I cranked on the starter for a long time and never flooded it.

With the fuel lines disconnected, I can blow fuel out the carb line easily. Maybe the LSN has dirt in it. I may back it out, blow fuel through it and then reset to flush the needle.
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Old Oct 28, 2011, 04:16 PM
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It could be the HSN clogged up too, I've had that happen on multiple nitro engines over the years.
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Old Oct 28, 2011, 07:07 PM
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It is priming good and fuel is coming out muffler when cranking the engine electrIc start and hand glow ignitor on engine. Tried a new plug, nuthin. I got a 1 second idle but couldn't replicate.

Found a traxxas thread with similar difficulties on old engine. I may just retire it and get an os 18
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Old Nov 02, 2011, 04:39 PM
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well, i did a little more reading and found a guy that used a handheld drill with a socket that fits the one-way bearing hex to start the engine. i tried it and was able to get the engine running.

my son and i ran the truck for an hour or more and had tons of fun. the engine runs real nice, but starting is still a bear.

if the engine will idle and spool up just fine...would it be safe to say there is nothing clogging the carb needles?

it seems like the carb just doesn't pump the fuel well enough. is this a sign of a worn piston?

thumb on the exhaust doesn't quite do it, but thumb over the air intake helps a bunch.

what about plugs...I'm using an OS#8. Should I try something hotter?

fuel: powermaster 15% with 18% oil.
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Last edited by TexasClouds; Nov 02, 2011 at 04:44 PM.
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Old Nov 02, 2011, 08:48 PM
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Another thing to check would be the fuel pressure nozzle that comes off the pipe make sure it is not blocked in any way as they can become blocked after a while from the fuel & oil residue.

Cheers.
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Old Nov 09, 2011, 12:18 AM
Joined Aug 2011
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sounds like your glow plug is giving out replace it and you should be fine!
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Old Nov 18, 2011, 05:32 AM
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USA, FL, Fort Myers
Joined Jun 2008
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most of the time when a nitro engine dies when removing the glow driver ( battery )
it has either too much fuel ( to ritch low end ) or the plug is going bad , and ive seen it happen on some siro engines if not warmed up before removing the glow driver . but that was a turbo plug . i would also recommend runing odonnel fuel 20% as ive ran it for many many years with success .
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