RE: Fluctuating fuel pressure

[Rich Kinsley <rlkinsley@xxxxxxxxx>]

You mean like a back pressure against the pump? Anything is possible but 
I don't believe I have a fuel temp problem anymore since the lines are 
out of harms way now and there is no mech pump near the heat source 
either. The carbs feel pretty cool now too as does the fuel log.

Rich Kinsley '64 Dodge Polara 4dr 318poly w/goodies

=====================================================================
Steve Charette wrote:
> 
> Ahh, that makes sense... the '64 just mysteriously shut off a couple of
> (inopportune) times on our trip.  Always on hot days and after sitting 
> for a
> while (fuel or food stops).  Most times it was as I was pulling out into
> traffic - ACK!  
> 
> Had the same trouble with the Travco last week when trying to level it - 
> had
> just gotten off the highway and it idled as we checked in to the 
> campground.
> It then sat and idled again for a while as we attempted to level it -
> finally stalling and not wanting to start again (we ended up changing 
> the
> bed so we could at least sleep head up - ever try to sleep with your 
> head
> lower than your feet?).  Started and ran great on the way home 
> yesterday.
> 
> This does make perfect sense - I hadn't had vapor lock in such a long 
> time
> it never occurred to me.  Is it possible that what Rich is seeing is 
> vapor
> pressure overcomes the pump pressure and prevents adequate flow of fuel?
> 
> SC
> 
> -----Original Message-----
> From: Schuyler Wrobel [mailto:sky62@xxxxxxxxxxxxx] 
> Sent: Monday, August 03, 2009 7:33 PM
> To: 1962to1965mopars@xxxxxxxxxx
> Subject: Re: Fluctuating fuel pressure
> 
> 
> hey Rich, here is something from my Don D. folder-
> 
> Pascals law fo Fluid Dynamics states that pressure is distributed with 
> equal
> force in all directions.( We teach this when teaching brake systems )As 
> long
> as the supply of fuel to the pump is sufficient (more than can be used 
> ). As
> fluid or fuel is used pessure will fall (at high RPM) It should not fall 
> be
> low 5 ideally.
> I would go ahead and run it. If it is not enough you will know the first
> time you wack the throttle Don Author of Return to Deutschland (True
> Adventure) Old Reliable (Mopar)
> 
> One of the big problems facing us to say when using mach fuel pumps is 
> that
> we are pulling fuel from the tank.
> When we reduce the presure in a liquid we also reduce its boiling point 
> or
> point when it convetrs from a liquid state to a gas state.
> It used to be  fuel manufacturers added  chemicals to reduce the 
> tendancy of
> fuel to boil and cause what we commonly called vapour lock.  Now because 
> all
> cars currnetly in production have fuel injection with a line running 
> full
> pressure from the tank to the injectors there is no longer any reason to
> worry about vapour lock conditions. However for us  with older cars with
> conventional fuel pumps which pull fuel at low pressure from the tank to 
> the
> pump and are engine mounted (so they absorb heat from the engine,) it 
> can be
> a real problem. Enough of a problem in some cases the engine will
> mysteriously quite after several successive stop lights in hot traffic 
> or
> suspicious no start conditions after a hot soak (sitting hot shut off 
> while
> you go inot a store for a loaf of bread for instance. When you go to 
> restat
> it doesnt want to start. Because it is mysterious often the ignition 
> gets
> the blame . In fact it is the fuel pump absorbing heat. Gasolines with
> ethonal are even worse for this condition. One cure that works well on 
> BB
> mopars is to build a very thin shiiled of aluminum and mount it on the 
> fuel
> pump attaching bolts so it shields the fuel pump from the front of the
> engine block which it almost touches at the side or business end of the
> pump. This will usually cure the problem on most cars and on some that 
> are
> real severe at least bring it to almost never status.
> The other solution that Bob aluded to is to install an electric pump.  
> The only problem is if you install a garden variety pump it may not be 
> able
> to keep up and if shut off just makes the regular pump work harder 
> severly
> limiting it violume. A good electric pump that will handle everything by
> itself is often very noisy  which is something that is not a lot of fun 
> in a
> street car.  I think there are some new brands of pumps that are not so
> noisy out there now but I havent tried them. I did find a mech pump 
> recently
> that has its business ends lower and farther away from the block. I am
> getting ready to try it out to see if it is a reasonable solution.
> Don
> Author of
> Return to Deutschland (True Adventure)
> Old Reliable (Mopar)
> 
> maybe some of this will help?
> 
> Schuyler 62 Dodge Dart 440 wagon w/ Poly 318
>   <http://www.1962to1965mopar.ornocar.org/ml-wrobel62.html>
> FYI - I Do the Decal designs for the Poly head 318 and more! email me 
> with
> your needs -
>   <sky62@xxxxxxxxxxxxx>
> 
> 
> 
> On Aug 3, 2009, at 11:58 AM, Rich Kinsley wrote:
> 
> >
> >
> >
> > Rich Kinsley '64 Dodge Polara 4dr 318poly w/goodies
> >
> > Things seem to be getting worked out nicely but I do see a puzzling 
> > phenomenun. I set the pressure regulator to 6psi, let it run till it 
> > warms up and it drops maybe down to 4psi. I swapped the press 
> > regulator and it did the same thing. I guess I should get another fuel 
> > pressure gauge and install it before the regulator to see if the pump 
> > output is consistent.
> >
> > Anybody see a similar thing happen? It actually dropped to 2.5psi once 
> > when it got real warmed up. It hasn't affected the performance though.
> >
> >
> > ----
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> >
> > '62 to '65 Mopar Clubhouse Discussion Guidelines:
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> >
> 
> 
> ----
> Please address private mail -- mail of interest to only one person --
> directly to that person.  I.e., send parts/car transactions and 
> negotiations
> as well as other personal messages only to the intended recipient, not 
> to
> the Clubhouse public address. This practice will protect your privacy,
> reduce the total volume of mail and fine tune the content signal to 
> Mopar
> topic.  Thanks!
> 
> '62 to '65 Mopar Clubhouse Discussion Guidelines:
> http://www.1962to1965mopar.ornocar.org/mletiq.html. 
> 
> 



Rich Kinsley '64 Dodge Polara 4dr 318poly w/goodies


----
Please address private mail -- mail of interest to only one person -- directly to that person.  I.e., send parts/car transactions and negotiations as well as other personal messages only to the intended recipient, not to the Clubhouse public address. This practice will protect your privacy, reduce the total volume of mail and fine tune the content signal to Mopar topic.  Thanks!

'62 to '65 Mopar Clubhouse Discussion Guidelines:
http://www.1962to1965mopar.ornocar.org/mletiq.html.