A nitro engine question

[Dewey]

Hi guys,

I have a DuraTrax Torq .12 engine and I've noticed something odd. It's a brand new engine and I've just finished running my 6th tank of fuel for the break-in. After running a half a tank through during a normal break-in run, I'd shut down the engine, (or it would stop itself for whatever reason). However, upon trying to re-start I would have a heck of a time. I would attempt to prime the carb with a couple of pumps from the tank pump (built-in plunger), however it would appear as though there is a back pressure pushing the fuel back into the tank from the carb...I would have to pump rigorously just for the fuel to overcome the slight pressure from the carb fuel inlet for fuel to reach the carb, and as soon as I stop pumping ...I watch as the fuel get sucked back or pushed into the tank. After the engine has cooled, it pumps nicely into the carb with no apparent back pressure.

Is this normal, or should I look for alternate methods of priming? Is there a thermodynamic reaction I'm not accounting for. I slept through most of my physics classes, so any help or assistance is very welcome.

The truck I'm running is a Dura Trax Maximum ST



Dewey

[Justin Mahn]

This is normal for an overheated engine. You should richen it about a
quarter to a half a turn and try to tune the low end needle to match it
after it warms up. Your fuel is instantly vaporizing when it hits the too
hot carb, and the expanding gas is pushing the fuel back towards the fuel
tank. This is known commonly as vaporlock. Keep the engine tuned below
maximum performance so that you don't overheat. Don't run it too lean to
produce smoke.


Also . . . this group is text only. Please post future messages without
HTML.

--
Justin Mahn
remove Panties to reply


"Dewey" <schmutz@NOSPAM.shaw.ca> wrote in message
news:HkXVa.564932$ro6.12837116@news2.calgary.shaw. ca...
Hi guys,

I have a DuraTrax Torq .12 engine and I've noticed something odd. It's a
brand new engine and I've just finished running my 6th tank of fuel for the
break-in. After running a half a tank through during a normal break-in run,
I'd shut down the engine, (or it would stop itself for whatever reason).
However, upon trying to re-start I would have a heck of a time. I would
attempt to prime the carb with a couple of pumps from the tank pump
(built-in plunger), however it would appear as though there is a back
pressure pushing the fuel back into the tank from the carb...I would have to
pump rigorously just for the fuel to overcome the slight pressure from the
carb fuel inlet for fuel to reach the carb, and as soon as I stop pumping
....I watch as the fuel get sucked back or pushed into the tank. After the
engine has cooled, it pumps nicely into the carb with no apparent back
pressure.

Is this normal, or should I look for alternate methods of priming? Is there
a thermodynamic reaction I'm not accounting for. I slept through most of my
physics classes, so any help or assistance is very welcome.

The truck I'm running is a Dura Trax Maximum ST



Dewey

[Dewey]

Thanks for the advice. I will try it out soonest.

BTW...I'm a bit of a techno-peasant....did my post come up like a website? I
thought HTML was for websites. Sorry for the mix-up.

Anyway, I'll search around the menus and try to figure out what and how HTML
is doing in my email post.

An honest question if I may though; How or what difference does having a
HTML msg vice a text msg make in this newsgroup?


Anyway, thanks for the help!


Dewey


"Justin Mahn" <gabrilPanties@tcainternet.com> wrote in message
news:vihvlql5ihjuf5@corp.supernews.com...
> This is normal for an overheated engine. You should richen it about a
> quarter to a half a turn and try to tune the low end needle to match it
> after it warms up. Your fuel is instantly vaporizing when it hits the too
> hot carb, and the expanding gas is pushing the fuel back towards the fuel
> tank. This is known commonly as vaporlock. Keep the engine tuned below
> maximum performance so that you don't overheat. Don't run it too lean to
> produce smoke.
>
>
> Also . . . this group is text only. Please post future messages without
> HTML.
>
> --
> Justin Mahn
> remove Panties to reply
>
>
> "Dewey" <schmutz@NOSPAM.shaw.ca> wrote in message
> news:HkXVa.564932$ro6.12837116@news2.calgary.shaw. ca...
> Hi guys,
>
> I have a DuraTrax Torq .12 engine and I've noticed something odd. It's a
> brand new engine and I've just finished running my 6th tank of fuel for
the
> break-in. After running a half a tank through during a normal break-in
run,
> I'd shut down the engine, (or it would stop itself for whatever reason).
> However, upon trying to re-start I would have a heck of a time. I would
> attempt to prime the carb with a couple of pumps from the tank pump
> (built-in plunger), however it would appear as though there is a back
> pressure pushing the fuel back into the tank from the carb...I would have
to
> pump rigorously just for the fuel to overcome the slight pressure from the
> carb fuel inlet for fuel to reach the carb, and as soon as I stop pumping
> ...I watch as the fuel get sucked back or pushed into the tank. After the
> engine has cooled, it pumps nicely into the carb with no apparent back
> pressure.
>
> Is this normal, or should I look for alternate methods of priming? Is
there
> a thermodynamic reaction I'm not accounting for. I slept through most of
my
> physics classes, so any help or assistance is very welcome.
>
> The truck I'm running is a Dura Trax Maximum ST
>
>
>
> Dewey
>
>

[Justin Mahn]

Usenet is traditionally text only. When you post in HTML, most people see it
as you do in editing mode, showing all tags in raw source form. As you
might guess, this is hard to read. Good luck with your engine!

--
Justin Mahn
remove Panties to reply


"Dewey" <schmutz@NOSPAM.shaw.ca> wrote in message
news:Vw7Wa.595924$Vi5.14818837@news1.calgary.shaw. ca...
> Thanks for the advice. I will try it out soonest.
>
> BTW...I'm a bit of a techno-peasant....did my post come up like a website?
I
> thought HTML was for websites. Sorry for the mix-up.
>
> Anyway, I'll search around the menus and try to figure out what and how
HTML
> is doing in my email post.
>
> An honest question if I may though; How or what difference does having a
> HTML msg vice a text msg make in this newsgroup?
>
>
> Anyway, thanks for the help!
>
>
> Dewey
>
>
> "Justin Mahn" <gabrilPanties@tcainternet.com> wrote in message
> news:vihvlql5ihjuf5@corp.supernews.com...
> > This is normal for an overheated engine. You should richen it about a
> > quarter to a half a turn and try to tune the low end needle to match it
> > after it warms up. Your fuel is instantly vaporizing when it hits the
too
> > hot carb, and the expanding gas is pushing the fuel back towards the
fuel
> > tank. This is known commonly as vaporlock. Keep the engine tuned below
> > maximum performance so that you don't overheat. Don't run it too lean
to
> > produce smoke.
> >
> >
> > Also . . . this group is text only. Please post future messages without
> > HTML.
> >
> > --
> > Justin Mahn
> > remove Panties to reply
> >
> >
> > "Dewey" <schmutz@NOSPAM.shaw.ca> wrote in message
> > news:HkXVa.564932$ro6.12837116@news2.calgary.shaw. ca...
> > Hi guys,
> >
> > I have a DuraTrax Torq .12 engine and I've noticed something odd. It's a
> > brand new engine and I've just finished running my 6th tank of fuel for
> the
> > break-in. After running a half a tank through during a normal break-in
> run,
> > I'd shut down the engine, (or it would stop itself for whatever reason).
> > However, upon trying to re-start I would have a heck of a time. I would
> > attempt to prime the carb with a couple of pumps from the tank pump
> > (built-in plunger), however it would appear as though there is a back
> > pressure pushing the fuel back into the tank from the carb...I would
have
> to
> > pump rigorously just for the fuel to overcome the slight pressure from
the
> > carb fuel inlet for fuel to reach the carb, and as soon as I stop
pumping
> > ...I watch as the fuel get sucked back or pushed into the tank. After
the
> > engine has cooled, it pumps nicely into the carb with no apparent back
> > pressure.
> >
> > Is this normal, or should I look for alternate methods of priming? Is
> there
> > a thermodynamic reaction I'm not accounting for. I slept through most of
> my
> > physics classes, so any help or assistance is very welcome.
> >
> > The truck I'm running is a Dura Trax Maximum ST
> >
> >
> >
> > Dewey
> >
> >
>
>

[Jerrit Tyler]

Dewey, I have seen carbs do this when the engine has stopped running
due to overheating but it's also possible you are vapor locking due to
too much fuel.
I have always started my engines with 3 turns out and eventually
settled at 2 1/2 turns out but all motors vary a little.
One other thing to try is to remove the carb and apply a very small
amount of gasket sealer to the base of the carb to prevent air leaks.

The best way to prime it is to place your finger over the exhaust tip
on the muffler and pull the pull starter a few times.
Replace your fuel tubing with clear tubing if it is not already clear
to see the fuel flow up to the carb.

Jerrit



"Dewey" <schmutz@NOSPAM.shaw.ca> wrote in message news:<HkXVa.564932$ro6.12837116@news2.calgary.shaw.ca>...
> Hi guys,
>
> I have a DuraTrax Torq .12 engine and I've noticed something odd. It's a
> brand new engine and I've just finished running my 6th tank of fuel for
> the break-in. After running a half a tank through during a normal
> break-in run, I'd shut down the engine, (or it would stop itself for
> whatever reason). However, upon trying to re-start I would have a heck
> of a time. I would attempt to prime the carb with a couple of pumps from
> the tank pump (built-in plunger), however it would appear as though
> there is a back pressure pushing the fuel back into the tank from the
> carb...I would have to pump rigorously just for the fuel to overcome the
> slight pressure from the carb fuel inlet for fuel to reach the carb, and
> as soon as I stop pumping ...I watch as the fuel get sucked back or
> pushed into the tank. After the engine has cooled, it pumps nicely into
> the carb with no apparent back pressure.
>
> Is this normal, or should I look for alternate methods of priming? Is
> there a thermodynamic reaction I'm not accounting for. I slept through
> most of my physics classes, so any help or assistance is very welcome.
>
> The truck I'm running is a Dura Trax Maximum ST
>
>
>
> Dewey
>
>
> --

[Juan Lauda]

"Jerrit Tyler" <jerrit@grnet.com> wrote in message
news:ae7c35cb.0307310605.53054a82@posting.google.c om...
> The best way to prime it is to place your finger over the exhaust tip
> on the muffler and pull the pull starter a few times.

It's the only way to prime it if you don't have a primer pump.

In-tank primer pumps are a PITA. If you don't want to spend more time
cleaning castor oil off the top deck than you do running the car then remove
the primer and seal the hole with a self-tapping screw and O-ring.