TBI fuel pressure regulator question

[Bruce]

Seems terribly low to me.
Bruce



----- Original Message -----
From: "Jay Vessels" <jwvess00 at home.com>
To: <gmecm at diy-efi.org>
Sent: Monday, September 17, 2001 9:54 PM
Subject: Re: TBI fuel pressure regulator question


> Hi there!
>
> Dad rigged a fuel pressure gauge today and powered the pump.  The gauge
was
> connected to the fuel filter outlet such that the fuel filter was only
> connected to the gauge (i.e. no return path, just pressure to the gauge).
> Reading was 15.5 psi.  I assume this is enough for a TBI pump deadheading
> into a gauge.
>
> The return line from the TBI doesn't have any fuel flowing from it when
the
> pump is running, so Dad's going to tear into the TBI and make sure it's
> okay inside.
>
> The real problem for me is that Dad's got the car, and his house is 90
> miles away from mine, so we're having to work through some of this by
phone
> until I visit again.
>
> Jay Vessels
> 1982 Chevrolet S-10 Sport, 2.8V6 TBI
> 1994 Chevrolet Cavalier Z24 Conv., 3.1V6 MPI
>
>
> At 03:45 PM 9/17/01 -0400, you wrote:
> >
> >>  Carefully Check the Fuel Cap , The Fuel Pickup , The Fuel Line
> Orientation,
> >      Check The Strainer @base of fuel pickup. A bone yard Pump may have
spun
> >      one of the plastic pump rotors. Pump internal bypass may have a
> problem.
> >      Watch the FP relay Voltage vs Bat Voltage. Major Irregularities [
Draw]
> >      indicate a FP failure in progress, or a major restriction.
> >     Double , Double Check ground connections and resistance values.
> >     Something as silly as a small piece of debris in pump can make you
go
> >     bonkers. Anything that can go wrong usually will do so.
> >     Len
> >
> >
> >> >Hi there!
> >> >
> >> >Dad and I are currently converting my cousin's '85 Caprice 305V8
> >> >Q-jet/700R4/federal emmissions to a TBI system from an '89 (305V8 TBi
> >> >1228746 ECM/700R4/Federal emmissions) and have run into an interesting
> >> >problem.
> >> >
> >> >I finished modifying the '89 harness and finally got it installed
today.
> >> >Dad finished plumbing the fuel lines, and we decided to check for
> leaks.  I
> >> >jumpered across the fuel pump relay (ECM not installed yet) to run the
> >> >pump.  We had fuel all the way to the TBI, but almost no fuel came
from
> the
> >> >return line.  Cracking open the fuel feed line at the TBI after
removing
> >> >power from the pump yielded a spray of fuel.  The return line during
this
> >> >test was simply a 3/8" steel line from the TBI emptying into a small
jar
> >> >(not connected to the fuel tank).  The canister vent line was unhooked
to
> >> >make sure the tank was venting.
> >> >
> >> >It seemed odd, but we buttoned everything up and tried to start it.
It
> >> >would spin over fine, and acted like it wanted to start but only hit
once
> >> >or twice.  it would not run on its own.  Using an inductive timing
light,
> >> >we verified that spark was getting to the plugs (we tried a couple,
not
> all
> >> >8).  Shining the timing light at the injectors shows fuel is being
sprayed
> >> >into the throttle bores.  We also verified that the distributor timing
is
> >> >close (i.e. we don't think we're off a tooth or anything like that).
> >> >
> >> >Another thing I noticed, besides the lack of fuel flowing from the
return
> >> >line, is the fuel pump is LOUD.  I can hear it run quite loudly.  I
can
> >> >hear the pump in all the other cars, but they're not nearly as loud as
> this
> >> >one.  It is a junkyard piece so I don't know it's history.  Dad is
> going to
> >> >get a fuel pressure gauge tomorrow.
> >> >
> >> >It acts just like it's not getting fuel, but I know the injectors are
> >> >firing.  Is this a case of really low fuel pressure, or is there
perhaps a
> >> >problem with the throttle body (i.e. pressure regulator)?
> >> >
> >> >Any ideas are greatly appreciated.
> >> >Jay Vessels
> >> >1982 Chevrolet S-10 Sport, 2.8V6 TBI
> >> >1994 Chevrolet Cavalier Z24 Conv., 3.1V6 MPI
> >> >
> >> >
> >> >
> >> >
> >>
>
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