Grounding is certainly important, and on our vintage ('85) you need to add a
wire from the alternator to the starter to avoid low voltage as well,
especially since you seem to have a lot of corroded connections:
http://www.van-cafe.com/home/van/page_780_449/alternator_cable_upgrade.html

Check the ground strap from the front of the transmission to the body too,
both the engine and transmission should be grounded to the chassis.

Hopefully you are on the road to recovery!

Stuart

From: Craig Cowan [mailto:phishman068@gmail.com]
Sent: Saturday, February 02, 2013 12:19 PM
To: Stuart MacMillan
Cc: vanagon. com sending
Subject: Re: TERRIBLE GAS MILEAGE/Running Cold?

Well, i've gotten a step closer to solving the running issues, i believe.

Yesterday i found the temp gauge will still dive above 60mph, and it was
warmer (25*F or so?), but i think the issue is bigger than just a
faulty/weird thermostat. I think my 8mpg running is in part coming from
terrible grounds.

When I first built this bus, for whatever reason I seem to have forgot to
deal with the grounds?

My chronically slow starting condition suddenly made since, and i dove into
the engine bay to find the braided cable snapped off in my hand, and all the
ring terminals looked like crap.
I cleaned up some of the ring terminals and replaced the ends of a few
others. I put a 4 gauge grounding cable from the engine to the body and from
the starter motor's lower bolt to the body.
My starting is still screwed up, but seems improved.

I can't wait to see how this effected fuel economy. I imagine the entire
fuel injection system was reading poorly if the grounds weren't sound.
Hopefully my messing with wires didn't awaken any new beasts.....

We shall see.

-Craig