Date: Sun, 17 Feb 2002 08:37:46 -0800
Reply-To: Walter Evens <wrevens@MYEXCEL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Walter Evens <wrevens@MYEXCEL.COM>
Subject: Re: Last question of the night
Content-Type: text/plain; charset="iso-8859-1"
I have not had much experience with EFI but this is what I've learned so
far.
'85 Dodge Aries; Chilton manual said fuel pressure should be 15 psi. Pulled
the line off the regulator and psi from the pump was 15. However, spoke to
someone at the parts store and was told EFI fuel pump pressure should be in
the 80s. Pulled the pump and tested. It was a cheap plastic pump which had
"separated" and was leaking out the side. Put it back together and the
pressure jumped to the 80s. Regulated pressure was to be 15 psi.
'87 Isuzu Impulse; Pulled the line coming to the regulator. Pressure in
the 80s. Checked the pressure after the regulator while cranking the
engine, also in the 80s. Was told by someone in the parts store that the
regulator is actuated by vacuum. Therefore, must be tested while engine is
running. No vacuum, no regulated pressure. Apparently EFI uses full
pressure to start and then regulates after wards.
'85 Vanagon. Fuel comes from pump to tee; from tee to fuel rails; from fuel
rails to regulator; apparently regulated by some sort of "back pressure"
method as the regulator is AFTER the fuel injectors and not BEFORE. Excess
fuel returns to the tank from the regulator.
All my tests were conducted with the engine not running. Just turning on
the ignition switch, pump pressure, 80 psi. Regulator to fuel tank
pressure, 70 psi. Cranking pressure: fuel pump, 90 psi. Regulator to fuel
tank, 80 to 90 psi. As the Vanagon regulator has a vacuum fitting, I would
hazard a guess that like the Isuzu, it utilized vacuum to regulate or in
other words, no vacuum, no regulation. However, with the Vanagon regulator
using "back pressure", am not sure if I'm comparing apples to apples.
I will need to do a fuel volume test and pull the injectors and check the
spray pattern.
One last note. The pump used to make a louder noise when I turned on the
key than before the vehicle died.
Walter Evens
Hesperia, CA, USA
2-85GLs
----- Original Message -----
From: "David Beierl" <dbeierl@ATTGLOBAL.NET>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Saturday, February 16, 2002 9:49 PM
Subject: Re: Last question of the night
> At 12:24 AM 2/17/2002, Walter Evens wrote:
> >Fuel pressure at the pump is 80 psi and about the same from the regulator
> >to the tank.
>
> Can you restate that? Pressure from the regulator to the tank ought to be
> about zero, and at the pump you should see the regulated pressure of 2.5
> bar over manifold pressure -- about 36 psi I think with engine stopped.
>
> If you're saying what I'm hearing, sounds like a plug in the fuel return
line.
>
> david
>
