TBI fuel pressure regulator question

[Bob Valentine]

Finally, a thread with no nuclear content!

Pressure is one part of the equation, volume is the other.   How's the flow
with the feed line unhooked from the TBI?  Sure the feed & return aren't
somehow swapped?   

-> Bob Valentine
-> bob at tecmark.com

At 10:51 PM 9/16/2001 -0400, you wrote:
>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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