Date:         Sun, 15 Aug 2010 10:38:34 -0400
Reply-To:     mordo <helmut.blong@GMAIL.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         mordo <helmut.blong@GMAIL.COM>
Subject:      VERBOSE: fuel pump, ethanol, cavitation
Content-Type: text/plain; charset=ISO-8859-1

O, List,

I've been reading a lot of the discussion both here and on the Samba about
fuel pump cavitation since I had a discouraging failure en route to the
Outer Banks Saturday a week ago. I'd appreciate the collective wisdom of the
list on this incident.

Van is generally running very well tho' I was a bit apprehensive of my
instrument cluster after tearing the foil thus worried that any warning
signs won't be reported. So, traffic from Springfield, VA on 95S was hateful
as usual and that day it was dreadful all the way to 295 interchange near
Richmond. Dodged the back up on 64E by going down to 460E, wade through
Norfolk area and on to NC 168/158 and am shortly mired in a hellish, 20 mile
debacle of too many damned vehicles all going to the same place. And, it's
hot, hot, hot, approximately 99F "real feel" that day and the rad fan is
cycling on and off regularly and occasionally up to high speed (that's a
surprising sound). Stop and go, creeping, crawling with the AC on. About
four miles before the bridge over the Currituck Sound, I hear what I
interpret is a wheezing sound from the cooling system and the engine
sputters to a stop. We pull over onto a grassy verge and curse the gods for
their cruelty. I try starting again and it kicks over, runs momentarily and
the sputters to a stop again. Wheezing sound was present again.

After hassling with an ESL support operator at my motor club, I get in to
tell the operator the VIN. I crank it over again just for kicks and it
starts and runs normally. So, I say, "Never mind, it's running again. I'll
call if I need a tow." We drove about 200 yards and kaput. Try to start
again and it sputters and coughs and kaput. And then the starter won't crank
over. Wheezing sound again. After a long, hot ride in the tow truck cab
(three people plus driver) we are at our destination and I ignore the van in
favor of several anodyne adult beverages.

Next day, I start it and run it and discern that the wheezing is a noisy,
whining fuel pump. It was an aftermarket pump, about three years old so I'm
willing to believe that it is failing. So, I order a replacement from
BusDepot. Replace it and the filter. The old filter bled rusty-looking
fuel."Hrmmm," says I. Starts rough but eventually runs fine. On the way back
to Baltimore, I start to get the whining fuel pump sound again and
occasionally, idling at stop lights, the engine quits. Restarts normally and
runs well at high speed, pulls strong all the way to Baltimore. So, to
summarize:


   1. Hot ambient temps
   2. fill up in southern Virginia with 10% ethanol fuel
   3. fine rust in fuel filter before replacement
   4. new Bosch pump still have whining sound
   5. Engine runs well under load, acceleration normal
   6. Sputters at hot idle and sometimes quits
   7. cleaned the tank three or four years ago

I have read of the theory that ethanol-blended gasoline is responsible for
cavitation, its specific gravity being lower than straight gasoline. I've
read the theory that the generic Bosch pump is too fast for gasohol and that
a resistor in line on the pump is the answer. I have experienced the effects
of cruddy fuel choking the fuel pump and my experience was inconsistent with
previous misadventures. That usually presented as choking and losing power
under load.

What do you all think is the most likely culprit? I was under the impression
that most fuel around the mid Atlantic was 10% ethanol but perhaps I am
mistaken. I am suspicious of my fuel pressure regulator - haven't tested
fuel pressure in a couple of years.

Cheers,
--
mordo
1990 Carat