Date: Fri, 4 Aug 2006 08:21:22 -0700
Reply-To: Mark Drillock <mdrillock@COX.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Mark Drillock <mdrillock@COX.NET>
Subject: Re: Strange no start problem - issue with fuel pump relay - input
requested!
In-Reply-To: <20060804144337.49084.qmail@web33514.mail.mud.yahoo.com>
Content-Type: text/plain; charset=windows-1252; format=flowed
Zoran, you are right, the Bentley diagram for 88-89 has it wrong. I
wrote about this several months ago. Page 97.206 has the correct wiring
for the 2 engine relays, shown as 1990+. The fuel pump relay also
provides power to the injectors, pulsed by the ECU when the ECU pulses
the ground side.
You have one thing wrong though. The power to turn on both the relays
comes from the key switch but the fuel pump only runs when the ECU
provides ground to it on pin 85. The other relay(ecu relay) always has
ground on it's pin 85 so as soon as the key is turned on it turns on.
The fuel pump relay needs the key on too but then also needs the ECU to
provide ground on it's pin 85. If the fuel pump relay has power on it's
pin 86 but does not run for a couple seconds when the key is turned on,
the ECU may be at fault by not providing the ground on pin 85. Or the
relay could be bad, or the wire from the ecu to pin 85 may be bad.
Remember that this is not true ground, but ground through a transistor
inside the ECU, only when the ECU turns on the transistor.
Mark
Zoran Mladen wrote:
> Hi folks!
>
> Having a strange issue with an 88 Vanagon non-westy non-syncro. It did not want to start. We replaced the fuel injection relay and it started and ran nicely. We drove it about 5 miles and it died and refused to start. It is not getting fuel pressure and no fuel injector pulsing. Looking at the wiring diagram in Bentley we found an error. The Bentley claims that the "juice" for the injectors (which is delivered when the key is on) comes from the fuel injection relay. This is not true! It comes from the fuel pump relay. We verified that with a couple old harnesses as well.
>
> At any rate, if we jumper (30 to 87) the fuel pump relay, we get fuel pressure, the fuel injectors pulse, and the car starts right up. Doing more tests, we know that the fuel injectors are getting the proper ground signal from the ECM - hence the hall sender and all wiring is working - but not getting juice, which is triggered by a hot wire to the relay coming from the ECU. The ground is at the relay, but no juice to activate the relay.
>
> Also, with the car running (with the fuel pump relay jumpered), the fuel injection relay gets very hot.
>
> At this point, I am thinking there is either a problem in the ECU or in the harness. Perhaps some melted wires, causing the "no juice" from the ECU as well as causing the fuel injection relay to get hot. Do folks agree? Disagree? Love to hear opinions.
>
> Thanx!
>
> Z
>
>
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