Tank pressure Questions
#1
Tank pressure Questions
What are some symptoms of not enough fuel tank pressure ?
What are some symptoms of too much fuel tank pressure ?
What are some symptoms of too much fuel tank pressure ?
#3
Tech Master
iTrader: (1)
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
#4
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.
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.
Last edited by SteveG; 07-16-2004 at 11:16 PM.
#5
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 yadda.....@$#% WTF could be causing these engines to go lean when I'm getting off the throttle yet be so fat on the needles that it's tough to get them to rev let alone idle...I'm using 5" of fuel line from tank to carb....certainly thats not too much line is it It's almost as if when I jump off the throttle the fuel is getting sucked away from the carb
My tank is fine, not leaking and holds pressure....frig I've change the lines, tried various lengths of pressure line yadda yadda yadda.....@$#% 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
#6
Tech Regular
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?
havy
havy
#7
Tech Fanatic
iTrader: (23)
Join Date: Nov 2002
Location: 4373 Creek Road Chaffee,NY 14030 USA (716)783-5198
Posts: 831
Trader Rating: 23 (100%+)
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!
Best regards,
RayA
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
#8
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
#9
Tech Regular
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.
havy
havy
#10
I would check engine for signs of detonation. Sound like the head volume is too low ( head botton shimming).
#11
Regional Moderator
iTrader: (9)
Re: Bad Fuel cap seal
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 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
#12
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.
#14
New tank saves the day
#15
Tech Fanatic
iTrader: (23)
Join Date: Nov 2002
Location: 4373 Creek Road Chaffee,NY 14030 USA (716)783-5198
Posts: 831
Trader Rating: 23 (100%+)
Bad cap seal
Glad to hear your not scratchin your head any longer and racin again