TBI fuel pressure regulator question

[Bob Valentine]

That dead-head psi sounds a bit low.  You really need a inline pressure
test to see if the pump can maintain the VOLUME of fuel flow.  I've seen
port injected cars (~40 psi) run on TBI pumps - will idle, but heavy
throttle is a no-go.

Check the connection between the pump & the sender pipe, might be leaking.
Or the pump might be junk....

-> Bob Valentine
-> bob at tecmark.com

At 09:54 PM 9/17/2001 -0400, you wrote:
>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
>>> >
>>> >
>>> >
>>> >
>>>
>>----------------------------------------------------------------------------
>>> >To unsubscribe from gmecm, send "unsubscribe gmecm" (without the quotes)
>>> >in the body of a message (not the subject) to majordomo at lists.diy-efi.org
>>> >
>>> >
>>>-------------------------------------------------------------------------
---
>>>To unsubscribe from gmecm, send "unsubscribe gmecm" (without the quotes)
>>>in the body of a message (not the subject) to majordomo at lists.diy-efi.org
>>
>>----------------------------------------------------------------------------
>>To unsubscribe from gmecm, send "unsubscribe gmecm" (without the quotes)
>>in the body of a message (not the subject) to majordomo at lists.diy-efi.org
>>
>>
>
>----------------------------------------------------------------------------
>To unsubscribe from gmecm, send "unsubscribe gmecm" (without the quotes)
>in the body of a message (not the subject) to majordomo at lists.diy-efi.org
>
>
----------------------------------------------------------------------------
To unsubscribe from gmecm, send "unsubscribe gmecm" (without the quotes)
in the body of a message (not the subject) to majordomo at lists.diy-efi.org