One possibility is the  Hall sender in the distributor.  Can be
unpredictable.
John
1986 Westy
----- Original Message -----
From: "Woody Halsey" <WHalsey@SYA.ORG>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Wednesday, August 30, 2006 11:32 AM
Subject: sudden failure to fire

Dear All,

In the 20 years I have been happily driving my V'gon, through two
engines and more replaced parts than I care to think about, have gone
through just about every challenge discussed here over the years. The
one thing my beloved wagen has never done is fail to start. It has
always fired up "au quart de tour," as the French say. Until yesterday.

Here's what happened. Drove 40 miles to Logan airport, engine purring
through the all-new exhaust system. Parked. Went to a meeting at the
airport Hilton with the families of the students we were sending to
Italy last night. Retrieved van in parking lot and drove over to the
hotel to pick up colleague, wife, four kids and their 13 huge bags to
check in and 8 small backpacks to carry on. They marveled at the
capaciousness of the V'gon. (I took the middle seat out and carpeted the
middle section years ago.) Drove to the terminal. Unloaded. Turned key
to return to parking lot. She wouldn't start. Battery strong, engine
turned over and over and over. No go.

Went home on the back of the AAA flat bed, dropping van of at garage.

This morning, she started right up the first time and the mechanic
wondered why I was there. But then it refused to start the second time
he turned the key.

So, does anyone have an explanation?

So far we know:

a)          Battery strong

b)        Plenty of fuel, no sign of fuel pump problems.

c)          Spark string at the distributor cap (but terminals inside
have heavy black deposits - I scraped them off with my pocket knife -
probably should replace no matter what.)

Theories to date:

a)          Something to do with temp? (Started up when cooled down this
morning ...?)

b)        Loose wire somewhere?

c)          Vapor lock somewhere?

All suggestions welcome. Many thanks in advance.

Woody

83.5 V'gon

Haverhill, MA