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Fuel Vaporizes

Fuel Vaporizes

Old 03-16-2003, 02:05 PM
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Default Fuel Vaporizes

what does it mean when I have run my NMT for 6 minutes it stalls and to me it looks like the fuel vaporized either when it hit the carb or just before?!!!

PLEASE HELP ME!!!!
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Old 03-16-2003, 03:32 PM
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oh yeah this is break in too and i followed the instruction manual.
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Old 03-16-2003, 04:30 PM
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Default Fuel Vaporizes

corvettecrazy;

The problem you describe is called Vapor Lock. The engine is running too hot and the Heat is being transfered to the Carburetor. Very common in off-road vehicles with not enough air moving over the engine at slow speeds. Open your High Speed Needle a tiny bit, and try to cut the body out some more to allow more Airflow over the engine. This should fix the problem.
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Old 03-16-2003, 04:41 PM
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pops: the truck was running at idle not moving on a 60 degress day, I agree with you I think it is vapor lock but I dont know what to do, also there was no body on it at the time. It also stalled when I started to slowly circle my driveway.
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Old 03-16-2003, 04:49 PM
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Default Fuel Vaporizes

corvettecrazy;

Still sounds like Vapor Lock. Try opening the HS Needle and slowing the idle speed down some.
NOTE: An Engine CAN overheat while idling, especially if the idle speed is too high. Use the idle stop screw and NOT the transmitter to adjust your idle.
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Old 03-16-2003, 05:27 PM
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On a colder day you need to richen the motor. If it was very cold you may find it was running very lean. Try again but listen closely and tell us what the motor sounds like when it flames out.
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Old 03-17-2003, 12:31 AM
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also is the fuel line going near the head? or just wen it enters the carb?
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Old 03-17-2003, 08:20 AM
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Default Fuel Vaporizes

Originally posted by V-One S
also is the fuel line going near the head? or just wen it enters the carb?
GOOD POINT!!

I have had this problem before. Do NOT let the fuel line touch the Head or Pipe. This can cause your problem also.
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Old 03-17-2003, 12:25 PM
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ok its vapor lock...

1 could it be the stock fuel tubing?

2 what about fuel? does 20% nitro with 14% oil run cooler than 10% nitro with 20 % oil.

3 it is vapor lock but what do I do when the fuel vaporizes at the carb not when it hits the exhaust or anything else? the line doesn't touch the heat sink or exhaust.

4 what do I need to adjust to get the temp down?

5 should the wheels spin when the chassis is on blocks and at idle?

i had more but when I tried to attach a picture of the truck and it was too big it got erased. dont know why but it did so i had more ideas but I dont remember them now.
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Old 03-17-2003, 03:48 PM
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Default Hmmm.....

Originally posted by corvettecrazy
ok its vapor lock...

1 could it be the stock fuel tubing?

2 what about fuel? does 20% nitro with 14% oil run cooler than 10% nitro with 20 % oil.

3 it is vapor lock but what do I do when the fuel vaporizes at the carb not when it hits the exhaust or anything else? the line doesn't touch the heat sink or exhaust.

4 what do I need to adjust to get the temp down?

5 should the wheels spin when the chassis is on blocks and at idle?

i had more but when I tried to attach a picture of the truck and it was too big it got erased. dont know why but it did so i had more ideas but I dont remember them now.
Hmmm.....well there is still another possibility too. You could have your low end needle to lean and not providing enough fuel for you to idle correctly. Also a minor air leak will do that also. Just a couple of suggestions.
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Old 03-17-2003, 06:16 PM
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well it isn't the low end because that is factory set and there is no needle for it

if it was an air leak where would I check?
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Old 03-17-2003, 07:20 PM
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I hope you dont have an air leak. Check ya tank by putting it under water and blowing into it through the line. If you see bubbles, fix where it is comeing from. About your engine....cant help ya there.
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Old 03-18-2003, 06:50 AM
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Also its not a bad idea to replace the fuel lines, a small pin prick in the line will wreck an engine.
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Old 03-18-2003, 09:54 AM
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Originally posted by corvettecrazy

Ok its vapor lock...

1) Could it be the stock fuel tubing? (Probably not)

2) What about fuel? does 20% nitro with 14% oil run cooler than 10% nitro with 20 % oil. (Actually a Higher % of Nitro will run cooler, because of a wider needle setting and more raw fuel flowing through the engine. Stick with 20% Nitro and at Least 14% Oil)

3) If it is vapor lock but what do I do when the fuel vaporizes at the carb not when it hits the exhaust or anything else? the line doesn't touch the heat sink or exhaust. (The engine is TOO HOT)

4) What do I need to adjust to get the temp down? (Open the main Needle counter clockwise a few clicks at a time, until the temps come down or the performance suffers severly)

5 Should the wheels spin when the chassis is on blocks and at idle? (With the Wheels on the GROUND, a very slight creep is acceptable. You should not have to run after the Car/Truck at idle. On blocks the wheels may turn some, but better to lower your idle speed)

Last edited by popsracer; 03-19-2003 at 09:23 AM.
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Old 03-18-2003, 12:40 PM
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thanks to every one who help. I will work on my problem when I have some spare timeand the weather is right.
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