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Old 07-16-2004, 08:32 PM   #1
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Tank pressure Questions

What are some symptoms of not enough fuel tank pressure ?

What are some symptoms of too much fuel tank pressure ?
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Old 07-16-2004, 10:47 PM   #2
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Default Re: Tank pressure Questions

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What are some symptoms of not enough fuel tank pressure ?

What are some symptoms of too much fuel tank pressure ?
not enough will probably will have problems getting fuel to the carb
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Old 07-16-2004, 11:02 PM   #3
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to much can blow fuel out the exhaust excessivly when you let off the throttle after a hard wide open throttle and may stall the engine because the tuned pipe is loaded with fuel and it gets blown back into the engine by the tuned pipe when you open the throttle again. depends on how your tank is vented. This was a big issue on the first NTC3 tanks before they weht to the cap pressure fitting. To much will also make the engine finiky to tune and needle sensitive. to little is rarely a problem but usually a sign is that the engine will rev up hard and then lay over or die at wide open throttle. acts the same as having the top end needle to lean
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Old 07-17-2004, 12:06 AM   #4
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How about the engine not coming off the pipe after a high speed pass and\or a very insensitive low speed needle ? Tank pressure related maybe ??

Tank in question is on my LD3...engine is a new 12TR....everything is fine, no air leaks, no tank leaks etc etc...can have it blubberingly rich on the high side but the friggen thing just won't come off the pipe properly after a high speed pass and I can go nearly 3 turns in and out on the low end with little or no effect I've moved the pressure nipple on the stock pipe, tried various lengths of pressure line, tried the single chamber NTC3 pipe etc etc...pissin me off it is

Hey would the hole in the banjo being opposite the hole in the valve assembly have much if anything to do with what I'm talking about ? I'm considering drilling the single hole in the valve assembly straight through in an attempt to keep a head of fuel when I come off the throttle.

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Old 07-17-2004, 10:38 PM   #5
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Okay I'm really pulling my hair out here...two engines are now displaying the same symptoms in this chassis

My tank is fine, not leaking and holds pressure....frig I've change the lines, tried various lengths of pressure line yadda yadda [email protected]$#% WTF could be causing these engines to go lean when I'm getting off the throttle yet be so fat on the needles that it's tough to get them to rev let alone idle...I'm using 5" of fuel line from tank to carb....certainly thats not too much line is it It's almost as if when I jump off the throttle the fuel is getting sucked away from the carb
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Old 07-17-2004, 11:00 PM   #6
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Is the tanks stone filter allowing the fuel to flow well to the engine? Does it happen if you don't connect the pressure line and just use the tank fuel line?

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Old 07-17-2004, 11:07 PM   #7
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Default Bad Fuel cap seal

I believe you have a bad fuel cap seal.

Huge problem I had with the MTX-3 tank, untill upgrading the cap.

All the same symtoms.

I suggest trying a new tank.

Good luck!

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Old 07-17-2004, 11:39 PM   #8
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Yea havy it's like there is no fuel line pressure....yet the tank is holding pressure perfectly. I had it hooked up to an aquarium pump under water....no bubbles I was just looking at the tank thinking about that filter...it's brand new but I dunno it seems to flow just fine
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Old 07-18-2004, 05:30 AM   #9
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Wow, have you tried the engine on a diff car? ??Does the engine idle well, or does it have ups and down, (thinking carb seal). I know you mentioned you tried another engine (I think...). These tanks have been famous for O ring seal prob on the lid, but thats the only thing I know of. Try cleaning out the carb, make sure there is know foreign bodies there.

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Old 07-18-2004, 06:47 AM   #10
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I would check engine for signs of detonation. Sound like the head volume is too low ( head botton shimming).
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Old 07-18-2004, 10:56 AM   #11
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Default Re: Bad Fuel cap seal

Quote:
Originally posted by RayA
I believe you have a bad fuel cap seal.

Huge problem I had with the MTX-3 tank, untill upgrading the cap.

All the same symtoms.

I suggest trying a new tank.

Good luck!

Best regards,

RayA
I agree with RayA. I think its a bad fuel cap seal. The engine on my R40 suddenly started acting funny after running perfectly for 4 months. Displaying the same symtoms as yours. I tried everything to solve it. Then I checked my tank seal by putting dish washing liquid around the seal then blowing into the pressure line while the fuel line is sealed. I saw bubbles from the rear of my cap seal showing an air leak. I'm going to replace the tank on my next trip to the hobby shop. Hopefully that is all that was wrong.
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Old 07-18-2004, 08:43 PM   #12
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It's not the lid...checked and rechecked that but regardless I'm picking up a new tank tomorrow as one of the things on my list is that the internal filter might be causing some flow restriction.
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Old 07-19-2004, 07:02 AM   #13
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I had similar issues with my NTC3, I had the new tank, then tried the K Factory tank, RD Logics Pipe & no luck. I then went back to the AE duel chamber pipe & moved the pressure fitting to the front of the pipe & problem solved. It has been running sweet ever since.
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Old 07-20-2004, 07:57 PM   #14
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New tank saves the day
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Old 07-20-2004, 08:11 PM   #15
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Default Bad cap seal

Glad to hear your not scratchin your head any longer and racin again
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