Roger <Rogerspace2@AOL.COM> said -

For the past week or so, my '89 Westy has been suddenly loosing power (and
then immediately regaining it) repeatedly from once or twice over a ten
minute period to 8 or 10 times a minute or more.  The power loss makes the
whole van shake as if I have hit a large pot hole and I have noticed that
while this is happening, the tach can drop 500-1000 rpm.  Now, I know that
when I'm driving along at 50 mph in 4th gear and have an instantaneous power
loss that the engine can't possibly be dropping 1000 rpm.
<snip>

Roger -

I suspect your ECU, or the wiring connected to it.  I was having similar
problems a few months ago, and tried several solutions.  What finally cured
it was swapping out the ECU.

According to Darrell Boehler ( midwesty@midwest.net ) the giveaway is the
instant drop of indicated RPM.  The tach gets its signal from the coil, by
way of the ECU, and a bad solder joint or failing component will cause
exactly that problem.

You can test by banging sharply on the ECU while someone watches the tach.
If it drops, that's it.  Not a foolproof method, though.  Mine never
responded to banging on it, just got erratic as it got warmer.

Seems to me there was a related thread about coil problems, but I think the
symptoms were different.

If you have a chance to swap in another ECU, that would be the best check.

Good luck!

- Mike Finkbiner
'87 Westy
Moscow, ID

mike_l_f@hotmail.com

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