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Air pressure issues.

Air pressure issues.

Old 02-04-2014, 10:47 PM
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Default Air pressure issues.

Hi guys,

I am new to nitro rc, so my wife had me on a budget. I purchased a hsp MT cheap and used. I got her home charged batteries changed glow plug and after much stress she will only start if I pour fuel in the carby, but then she stops. Thinking maybe not enough pressure from exhaust I used my own lung power to keep her running and it worked. The exhaust isn't blocked but maybe I am wrong.

Any ideas????
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Old 02-05-2014, 01:11 AM
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When u disconnected the pressure line from the exhaust and blew into it and while the engine was running, did you put your finger near the pressure fitting to see if there was exhaust air pressure coming out of it?
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Old 02-05-2014, 01:29 AM
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Originally Posted by My ST-RR EVO View Post
When u disconnected the pressure line from the exhaust and blew into it and while the engine was running, did you put your finger near the pressure fitting to see if there was exhaust air pressure coming out of it?
There was very little air coming from the exhaust. I don't think it was enough to build pressure!
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Old 02-05-2014, 05:11 AM
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Originally Posted by Bern82 View Post
There was very little air coming from the exhaust. I don't think it was enough to build pressure!
either clean out the pipe or replace it.
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Old 02-05-2014, 07:13 AM
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Make sure you fuel tank holds pressure.
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Old 02-06-2014, 12:12 PM
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You could check the pressure nipple on the pipe, it could have a small part or piece of metal or something blocking it thats somehow got lodged in there when manufactured.

Last edited by ozziii; 02-07-2014 at 01:00 PM.
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Old 02-06-2014, 05:19 PM
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Ive seen many RTR cars that either has the low end needle all the way in, or had the idle completely closed.
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Old 02-06-2014, 10:11 PM
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It's is used so has been run before! I have cleaned out the exhaust and there was heaps of oil from the fuel in there. I even tested the air flow from exhaust with an air gun and it seems good! I have even done the good old set the 3 needles back to 0 and then make 2 turns on each but still nothing. I used to tune bikes but now I have full respect for these little suckers!

Even tho I haven't used it yet I love this sport!
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Old 02-07-2014, 01:52 AM
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Make sure your idle gap is around .7mm by looking down the carburetor without the venturi in.

Make sure none of the fuel or pressure lines are kinked or pinched in any way.

Disconnect the fuel line from the carb. Spin the engine and verify fuel is being forced out of the
fuel line. If no fuel, the problem is between the exhaust and the carburetor. ... lines, filter, tank, exhaust pressure nipple. If there is fuel, it's the engine side... carb, h/s needle assembly, tuning. I would try another glow plug regardless

Try unscrewing the entire high speed needle assembly from the carburetor and then disassemble it by unscrewing the high speed needle. Thoroughly clean it and its ports with an aerosol solvent. Reassemble. Reattach fuel lines.

Preheat engine to 200 degrees Fahrenheit.

(Make sure glow ignitor makes all of the coils of the glow plug illuminate.)

Start engine using good quality fresh nitro not the old stuff you may have gotten with the car.
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Old 02-07-2014, 02:01 AM
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Clean out the carby. If it's been run before the old fuel may not have been run out. It can gum up the carby.
Pull the carby off and try spraying some brake cleaner into the nipped.
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Old 02-07-2014, 06:10 PM
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New glow plugs and igniter! Carby has been cleaned for the 5th time!

I pulled the fuel line off the carby and turned motor with the roto. Fuel didn't move unless I blocked exhaust outlet (as per priming). Can the rubber exhaust gasket cause this? I know on a bike it has to be tight but on my rc it is loose!

Maybe I will just change it anyway!
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Old 02-08-2014, 06:02 AM
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Originally Posted by Bern82 View Post
New glow plugs and igniter! Carby has been cleaned for the 5th time!

I pulled the fuel line off the carby and turned motor with the roto. Fuel didn't move unless I blocked exhaust outlet (as per priming). Can the rubber exhaust gasket cause this? I know on a bike it has to be tight but on my rc it is loose!

Maybe I will just change it anyway!
Must be air tight. There's your problem. You have to build pressure in the pipe.
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Old 02-09-2014, 09:20 PM
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Yep Fixed the problem.

I got some high temp gasket maker from super cheap and she now fires and idols.

It comes with a silicone Gasket from the manifold but my LHS doesn't stock much for nitro because "Nitro just isn't popular enough"

Thanks guys for everything!
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