Date: Mon, 27 Aug 2012 02:59:50 -0400
Reply-To: David Beierl <dbeierl@ATTGLOBAL.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: David Beierl <dbeierl@ATTGLOBAL.NET>
Subject: Re: Poor Hot Start Discovery - midway through solution
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yville.ca.mail.comcast.net>
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At 09:54 PM 8/26/2012, Skip wrote:
>Wow! David, your knowledge and clarity (and generosity) of writing
>has me in awe, and your sense of humor has me in stitches!
Modest! You forgot modest! ;-)
> Not sure if the shipyard reference regarding the emergency brake
> is the funniest one (my company does business with EB, btw), or
> your statement that my theory is as close to being right while
> being totally wrong.
I have to give Terry Pratchett a good deal of the credit for that one.
>Well, perhaps additional reinforcement for the poor Temp II
>connector. We just returned from SO's sister's (1.5 hour drive that
>should take 1 hour). It's been raining all day, temps in the 70's,
>so the roads were wet. Guess what? While driving home - two-lane
>hwy, 50 miles/hr, the engine "lost power", mumbled, and we exited to
>the shoulder (safely, fortunately). Prior to this happening I hear
>a constant whine from the fuel pump (while driving at speed...above
>the road/engine noise).
Fuel pump whine usually means the inlet is restricted and the pump is
cavitating. If the supply is actually being shut off or almost off,
the engine won't be very happy; otherwise it's a warning to check
your filter if it's upstream of the pump, and maybe start thinking of
how to de-crud or replace the fuel tank. Blowing compressed air into
the tank outlet after removing the gas cap may clean crud off the
filter sock and give you some breathing time.
> I lifted the engine lid, took a look around, the engine was
> "fluttering" (about to die), SO reached her left foot over to rev
> up a bit, keep it going. I had my IR gun with me so I shot both
> heads (left - 4/3 was at 195F; right - 2/1 was at 215F).
Be interesting to see what the individual exhaust pipes read at that
point. Beyond that I've got no knowledge/opinion about the anomaly.
> I shut the engine down (radiator fan ran for awhile), then
> started it back up (still no power and the engine ran
> rough). After 5 minutes or so (engine on and off) - never had
> difficulty starting the engine, btw, it had power and we were off
> and running at 50/55 mph. This happened two more times (last time
> in our driveway and I was able to coast to the garage.
>
>Note - this happened prior to me reading the comments about
>"wet/loose" Temp II connector, so did not take the opportunity to
>jiggle the connection, etc. I was thinking, at the time, that it
>was a failing fuel pump, so I hit it with a large screwdriver just
>for good measure...
The USN standard mechanical cure is only warranted if you use the
proper tool, i.e. a monkey wrench. Other tools are likely to simply
damage the device.
>Theory on the above: Assuming the fuel pump is OK (it's new +4,000
>miles/8 months), then the whining fuel pump may be indicative of
>being told to pump a bunch of fuel (which didn't whine, btw, after
>we got going again...then started to whine before we lost power
>again), then it's the faulty Temp II female connector (maybe not
>defective, but wet and bad connection), that indicated to the ECU
>that the engine is cold while it is hot and rolling down the
>highway, thus causing an excessive rich condition, thereby flooding
>the engine out causing loss of power. However, is the fuel pump
>"on/off" or "variable speed"?
That lived in the house that Jack built? That whiny fuel gets
tiresome on long rides. Sorry... Ok, lessee. The fuel pump runs
any time the engine is turning, or more specifically any time there's
been an ignition pulse in the last couple seconds. It circulates a
tankful or more per hour through the fuel ring in the engine room and
back into the tank, by way of the fuel pressure regulator which
maintains a constant pressure across the injector orifices under all
operating conditions (though if you put a gauge on the test tee in
the fuel ring the gauge will fluctuate as things change).
Because the pressure across the injectors is constant, opening the
injectors for x milliseconds will inject y grams of fuel no matter
what the engine conditions are. If the supply system fails (pump
dies, inlet clogged, pressure regulator fails) then the engine will
either starve or in the case of the regulator, very possibly flood so
drastically that it may hydro-lock.
Assuming the supply is ok, if the T-II loses connection the ECU will
go open-loop and drastically enrich the mixture, which in my
experience can cause it to stagger and limp at highway speeds, and
die on coming to a stop.
>So, to test theory, I'm going to leave the Temp II connector
>disconnected, engine should start right up cold,
May even have trouble starting cold unless you hold your foot partway
down...I wouldn't do that.
> drive around (we live in the country - not much traffic, assorted
> farm field entrances to ditch a mumbling Vanagon) a bit, and see if
> I can recreate the fuel pump whine and the "loss of power" phenomena.
The whine and the T-II are not related. Neither one knows or cares
about the other. The whine may mean you're starved for fuel but also
may not. You've got the square filter before the pump, yes? Pinch
off the supply hose, pull the filter and see if you can blow through
it easily and/or if there's a teaspoon of crud in it. If you're
really interested, let it dry out and saw the end off. Anyway, deal
with the filter immediately and get it out of the way. Then if the
whine comes back you're likely looking at a plugged filter sock
inside the tank.
>Then (or perhaps before), I'll load the connector with dielectric
>grease and tighten the female ends on the connector.
Mr. Squirrel points out that the single-Faston connector is for the
gauge sender. I forget what your access is to T-II on the 1.9l but
I'd suggest if possible cleaning the male pins with contact cleaner
or brake cleaner and then shining them gently with 1500-grit carbide
paper or similar. Similar treatment to the female
side. Unfortunately the terminals always seat in the same relative
positions, so if there's been fretting corrosion it may not be
possible to get a reliable contact with the light pressures
available, at least without polishing off the tin. That could
require replacing sender or connector or both, or doing some creative
workaround. Y'know, a little less smugness and a few more O-rings to
seal up electrical connectors (a la Toyota) could have done these
folks some good.
Stick a vampire tap on the active T-II wire so you can run a wire up
front to a voltmeter. If it's showing you five volts then you know
that something's open. Hot, should be down in the low tenths.
Yrs,
d
