I'd say the odds are 3 to 1 that you need new ignition wires.  You
could first try a careful cleaning of the distributor cap (inside and
out) and the end of the coil where the connections are.  I use 99%
isopropyl alcohol and paper towels.  If there are obvious carbon
tracks on the inside of the distributor cap you should replace it.

I feel that the standard diagnostic procedure in these cases is to
mist the ignition wires and related components with a water sprayer
with the engine running in the dark.  Watch for sparks or faint
arcing; listen for misfiring.  Move the wires around carefully.

Larry A.

On Sat, Feb 5, 2011 at 12:32 AM, Jonathan Poole <jfpoolio@gmail.com> wrote:
> Howdy List,
>
> I've got an 83 air cooled vanagon that runs great but occasionally starts
> roughly when wet. �If it sits for a while in heavy rain it is slow to start
> and sort of mis-fires or misses when it first cranks then it stumbles and as
> it hits higher rpms (1500 and up) it clears it's throat so to speak and then
> runs normally/great.
>
> In the past week the van has been sitting and the last day or two have seen
> a lot of rain, at times heavy. �Tonight I went out to start the van and it
> would turn over fine but not hit at all. �I smelled a bit of gas when I went
> back to open the engine lid and also tried to start it with fuel turned off
> and the throttle open for a while to see if it was flooded. �I can do this
> because I have a fuel shut-off under the dash for security and high-altitude
> cold starting. �In any case, turning the fuel off didn't make any difference
> and the van was still not hitting and only spinning rapidly over at any
> throttle and with fuel off and on. �I did notice the tach needle jumping a
> small bit. �I then checked for power at the coil which was good, and I
> checked the opening/closing of the ignition points with an ohm meter while
> hand-turning the engine which looked fine. �I also checked for fuel pressure
> by opening the bleeder in between 3 and 4 and it looked like there was
> pressure/fuel. �After that I inspected the harness and noticed that the
> section running to the jetronic box is getting pretty wet under the air
> cleaner. �I relocated it to above the canister vent lines to get it up a bit
> but wasn't able to do much there. �After playing around with the harness
> etc. though when I went to try it again it started to hit a bit. �After lots
> of trying (try for 10 seconds or so then wait a few minutes for close to ten
> minutes) it finally started and soon after was running great. �Good thing I
> have a newish battery, starter etc.
>
> Also, even though I think that the van was getting plenty of fuel I wasn't
> able to confirm it since I don't have a remote start hooked up and was doing
> this troubleshooting alone. �I also don't really know if it was getting
> spark or not.
>
> The van has never done more than start roughly when wet so this was the
> first time it has done this exactly. I'm guessing that the way the van was
> parked or the amount of rain were just right for it to either not have spark
> or less likely enough fuel. �What I don't know is how to fix the problem.
> Have any of you dealt with symptoms like this? �Is it an ignition component
> problem, a wiring harness problem, the ecu, other? �It was annoying when the
> van occasionally started rough but now that I know it can prevent starting
> at all I intend to get to the bottom of the issue and fix it somehow. �Any
> suggestions or similar experiences appreciated.
>
> Thanks,
>
> Jonathan Poole
> '83 AC Westy
>