[V8] Strange no-start fuel issue

[Enzeder]

A booklet I have for the 4.2 V8 notes that "The engine can not be 
started if either of the signals from G4 and G28 are not present."
G4 = Crackshaft position sensor
G28 = Engine speed sensor

The booklet also notes that the car will continue to run if G4 fails 
after starting.  And the 4.2 has 2 fuel pump relays (not sure about the 3.6).

Supposition: If G4 is marginal, could the spritz of started fluid 
allow the engine to spin long enough to get a signal?  Seems unlikely 
- not sure how time would affect G4's operation.

Side note, what effect would the started fluid have on the MAF sensor


At 10:19 AM 4/28/2008, Scott Simmons wrote:
>I was under the impression that Tom could spray a spritz of starting
>fluid and have the car fire right up..... sounds like he has spark but
>not fuel?
>
>~Scott S.
>
>Korn, Bob wrote:
>
> >My faulty check valve only caused long crank times to get the car
> >started. Usually a first try of a few seconds, if the car didn't fire I
> >would stop and then restart, after a few more seconds it would always
> >fire.  This was after sitting for extended periods or overnight.   Tom's
> >saying his starts up first thing after an overnight, would rule out
> >check valve in my opinion.  Sounds more like a crank or timing sensor
> >issue?
> >
> >
> >BK
> >
> >-----Original Message-----
> >From: v8-bounces at audifans.com [mailto:v8-bounces at audifans.com] On Behalf
> >Of Scott Simmons
> >Sent: Monday, April 28, 2008 1:40 AM
> >To: toml99 at todomundo.com
> >Cc: v8audi
> >Subject: Re: [V8] Strange no-start fuel issue
> >
> >This could be a faulty check-valve at the fuel pump?  Letting fuel
> >pressure drop while sitting.
> >
> >~Scott S.
> >
> >toml99 at todomundo.com wrote:
> >
> >
> >
> >>Hi all, and congratulations to Roger on the new car.  As far as the
> >>3.6-4.2 debate goes, with my convenient local station today listing
> >>premium for $4.16 and diesel for a pleasant $4.64(I have a diesel
> >>truck)...I can't rationalize even wanting a 4.2(but would still like
> >>to testdrive one and feel the difference)     .....worse even is my
> >>1990 130 2 stroke outboard that burns about 8 gal/hr(somewhere between
> >>3-4mpg at running speed).  And for what it's worth, I just hit 110K,
> >>and my cargo nets are perfect....I also want to thank everyone else for
> >>
> >>
> >
> >
> >
> >>the enjoyable reading regarding the purchase of the vehicle...
> >>
> >>So here's the problem.  Car starts right up,runs/idles/drives great.
> >>I can even drive it 1/2 hour down the road, turn it off, starts right
> >>up.  If it sits for awhile(1/2 hour, up to today when it was 5 hours in
> >>
> >>
> >
> >
> >
> >>the ski area parking lot and was about 40 degrees out), cranks but no
> >>start.  Quick spray of starting fluid, and sparks right up. If I left
> >>it overnight in the driveway, will start first crank in the
> >>morning.   First time this happened, I tried the cold water on the
> >>sensors trick, and nothing.  So, in today's case, the motor was not
> >>even warm when I got back to it, so it's not necessarily a
> >>temperature thing, but is starting to seem like a time thing.   I
> >>also stopped twice on the way down for 5 minutes or so and started
> >>fine.  I'm guessing, something electrical is telling the injectors not
> >>to open, and that the starting fluid sparks it up and the fuel flows/or
> >>
> >>
> >
> >
> >
> >>some vacuum thing opens up when motor starts, and all is
> >>fine....If it wouldn't start at all, I'd check all the fuel delivery
> >>stuff, but it's running great(after it starts).  [In the 87 Saab that I
> >>
> >>
> >
> >
> >
> >>just rebuilt and had gone thru all the tests for "no start"(had fuel
> >>pressure/injectors worked/spark etc, decided to swap out the ECU
> >>and sparked right up].   I "blinked" out no fault codes the last time
> >>it wouldn't start.  Any Ideas?...Sincerely Tom La Plante
> >>
> >>