Date: Sat, 10 Mar 2001 05:25:44 -0800
Reply-To: Mark Drillock <drillock@EARTHLINK.NET>
Sender: Vanagon Mailing List <email@example.com>
From: Mark Drillock <drillock@EARTHLINK.NET>
Subject: Re: Help, GL wont start!
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These 2 relays are a somewhat confusing area of the wiring. I think
there may be errors in the Bentley wiring for this on page 97.124. Look
at page 97.206 and you will see 2 r/w wires from FP relay pin 87 as
Relay pin 30 should always have 12 volts as it has a wire directly from
the battery/alternator and this is the high current 12 volt source
switched by the relay to pin 87 when the relay is energized.
Whenever the ignition key is on, another 12 volts comes to the fuel pump
relay pin 86. This is the 12 volts used to energize the relay but ONLY
WHEN the ECU says to by providing a return path on pin 85. When you
first turn the key on, the ECU enables the fuel pump relay for a few
seconds to bring the fuel pressure up, then it turns the pump off. When
you turn the key all the way to start, the ECU enables the relay again
but only if it sees that the engine is turning.
pin 30 = 12 volts always
pin 86 = 12 volts with key on
pin 85 = ECU controlled return path (~ground)
pin 87 = 12 volts when ECU says so by ~grounding pin 85
The Vanagon fuel pump relay is the most common type in the world. Get a
new one for under $10 at any auto parts store to remove any doubt. Or
borrow one from just about any car, they are used for many things
besides fuel pumps.
Testing the pump and relay off the car is not a guarantee that they are
good. They work under a load when in the car.
You can always put a fuel pressure gauge on the fuel lines to see if you
have about 35 psi. If not, try hot wiring the pump for a few seconds to
see if the pressure comes up. Then figure out what is wrong.
> I guess we know who the smart guys are! Figure this out for me. NO voltage at
> the Fuel Pump. Fuel pump works when power is applied to it off the vehicle. With
> a good fuel pump relay (checked removed from van), relay energizes, +12vdc input
> (pin 30), 0vdc output (pin 87). According to the Bentley on pin 87, should have
> one r/w wire, when in fact my GL has two! Where does the second r/w wire go? My
> DCU relay is good also.
> Thanks to the Folks with real help,