[T3] Fuel pressure leak

[Jacob Adam Schroeder]

> When my car is running, I have a constant 28 psi on my fuel line.  The

> > second I turn off the key, the pressure immediately drops to about 20
> psi.
> >
> > The same is true before starting.  In other words, when I turn the key to
> > the first click, the PSI goes up to 28.  As soon as the pump clicks off,
> > the pressure drops immediately down to 20psi.  The pressure stays around
> 20
> > psi for an hour before it slowly begins to drop.  Last night, it was
> around
> > 17psi when I went to bed (about an hour after I turned the engine off),
> and
> > in the morning I was around 5 psi.
>
> This is perfectly normal, nothing to be concerned about.
>
>
Great, last year when I resurrected this car from sitting in storage (since
2006), I replaced all the fuel hoses.  My pump was replaced with a new unit
10 years ago, which is only maybe 5000 miles ago, but it did sit for a
while (although with gasoline in the tank).  Glad to hear that this is
somewhat normal.

Why is it that the line does not stay pressurized at 28 unless the pump is
running?  Even if it is normal, it just bugs me.  Is it some leak in the
pressure regulator?  A leak in the fuel pump check valve?  Possibly both?


> Should I be concerned about this?  It is always 28 psi when running, but
> > I'm concerned that whatever is causing the leak could be giving me a
> super
> > rich mixture.  If so, what is the likely culprit and is it an easy fix?
>  I
> > understand that our fuel pumps are difficult to find.
>
> I rebuild the pumps, so don't worry about finding a new one. One of
> the major causes of pump death is water and dirt that gets in via a
> cracked "overflow" hose. The OE part is NLA, so I finally made up a
> kit to replace it, and my parts should outlast the OE parts. The
> price is $25-33, including shipping and instructions, depending on
> the year.
>
>
Thanks Jim, I do have one of your kits (I think I ordered it around the
time you rebuilt my master cylinder), I plan on installing it soon.  Looks
like I have even more of an incentive to get to work on this item.



> > I began to investigate my fuel pressure after I experienced some sort of
> > "vapor lock" issue on Friday.  After the 25 mile commute from work to
> home,
> > my wife had me go back out for groceries.  When I tried to start the
> car, I
> > got nothing and I could hear air bubbles in the gas tank (presumably
> coming
> > in through the return).  Any thoughts?
>
> This is a fairly common hot weather problem. During the heat soak
> after shutdown, the engine compartment gets hot enough to boil the
> gas inside the lines. The gas vapor gets pushed backwards into the
> gas tank where it recondenses, because it's cooler there, then air
> gets sucked back into the fuel loop as the engine cools. It's not
> clear where the air gets in, but backwards thru the injectors is one
> possibility.
>
> The solution is to install a switch to run the pump briefly, before
> you try the starter. Just run the starter until the bubbles stop,
> then start the car. I have a kit for that, too, which includes the
> switch, wiring, mounting bracket, and instructions for $10 (MT) or
> $11 (AT.)
>


I like this solution and will probably contact you soon so that I can get
set up to prime the pump before starting on occasions like this.  I had to
turn the key on and off probably ten times on Friday before the bubbles
stopped.
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