TBI fuel pressure regulator question

[Shannen Durphey]

Or a split hose, or a bad pulsator.

I got to where I'd pay the $40 or so for a new pulsator just to know I wouldn't
be pulling the tank back down.

Shannen

LWester wrote:
> 
> Yes--if that was deadhead pressure, you've got a worn pump.
> 
> Lyndon.
> ----- Original Message -----
> From: "Bruce" <nacelp at bright.net>
> To: <gmecm at diy-efi.org>
> Sent: Sunday, September 17, 2000 9:29 PM
> Subject: Re: TBI fuel pressure regulator question
> 
> >
> > 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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