Date: Wed, 11 Mar 2015 16:02:47 -0700
Reply-To: mark drillock <mdrillock@COX.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: mark drillock <mdrillock@COX.NET>
Subject: Re: No Start Scenario
In-Reply-To: <2MHt1q00y08X5Fr01MHvra>
Content-Type: text/plain; charset=UTF-8; format=flowed
The fuel pump is at the far end of a chain of several things that all
must happen before the fuel pump will run when it is supposed to. In my
experience only rarely is the cause the pump itself or the relay for the
pump.
Both relays have to be installed and working for the fuel pump to run
like it is supposed to. The ECU controls the FP relay by switching its
ground pin on/off.
What you are experiencing is pretty common these days. One cause is a
burned out pin D15 of the main panel. This is the pin that the key
switch powers on to run the ignition coil and trigger the power relays
for the ECU and fuel pump. It is a black wire and you can measure at the
ignition coil black wires to see that the key-on power is reaching the
coil. From there the smaller of the black wires carries power over to
the 2 relay sockets to enable them. That is what you found missing, the
enabling voltage at pin 86 of the FP relay socket. Check the black wires
for voltage when the key is on.
Mark
John Goubeaux wrote:
> Hi Guys,
>
> 2WD 90 2.1
>
> I'm trbl shooting a NO start scenario.
>
> Starter cranks over the engine just fine. I Do NOT hear the FuelPump pre
> cycle - at all - when ignition goes to the ON stage SO I headed in that
> direction and used the FuelPump Relay diagnose from this page:
> http://www.vanagonparts.com/fuel_pump_relay.html - which BTW looks like
> it is derived from the "Dijifant Guide"
>
> So starting with the FP Relay:
>
> I pulled the Relay
> I confirmed that # 30 has battery current BUT # 86 does NOT
> I jumped #87 with #30 and FP whirls away ( so FP does work )
> I checked continuity with #85 to ground with engine cranking and I have
> continuity ( So ECU is going to ground )
>
> So, what does the fact that I do NOT get battery current from # 86 mean
> ? And is this from the Ignition switch? ( or should I have left the
> relay plugged in while testing ?) There is No indication in the steps
> other than to "diagnose the circuit". I'm unclear IF that circuit is
> energized from the FI Relay OR the ignition switch. So this is where I
> am stuck.
>
> I've got a new ignition switch and relays on the way so can do some
> swapping out AND intend to replace the ignition switch anyway as it IS old.
>
> Can I assume that at this point the ECU and FP are OK and that it's
> likely a relay, ignition switch, and or connections in between ?
>
> Thanks for any advice
>
> PS:I know there is a lot of info online already on this topic, BUT I've
> yet to find a thorough diagnostic step by step with ALL the needed info.
>
> -john
>
>
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