I know it's been said, but like most anything, it's usually the "lump
sum of the little details" that make the big difference.

If possibly, trouble shoot in a logical order.

The "thump"?

Could it be one or more of the rubber mounts on the engine carrier are failing?

Could also be the exhaust wiggling a little and hitting something at
certain RPM's. (like from a start. Lower RPM's with the load of
getting the van moving)

Just a thought.

Best of luck.

Neil.

On Wed, Mar 5, 2008 at 1:40 PM, BJ Feddish <bfeddish@netreach.net> wrote:
> OK, awhile back I posted about my van hesitating. If you remember I took it
>  to my mechanic who cranked the AFM screw to get it to run rich. The
>  hesitating went away, the van ran pretty good but I was down to 11 MPG.  I
>  took it back, he cranked it back the other way, still ran OK but now we had
>  more hesitation. This type of hesitation was where there was a power loss
>  for a few seconds then the engine went back to normal. I thought I could
>  deal with this until spring but then it started stalling at lights and my
>  mileage was still crap. I decided to take it to a well known shop about 45
>  NE of me. They fixed my ground wires, replaced the O2 wire and set my
>  timing, idle and C02 to factory specs. After a vacuum check everything
>  looked fine except a slight leak at the throttle body.  I thought I was
>  going to be getting a great running van back but that was not the case.  Low
>  speed is worse than it's ever been. It's almost as if there was a tennis
>  ball under the gas pedal. If I'm trying to accelerate in 2nd gear there just
>  seems to be no power. There are no "big" hesitations but now I have allot of
>  little ones like someone was tapping on a switch.  The low power at low
>  speeds is frightening.  The van idles fine now and traveling at high speeds
>  seems to be slightly better than before this latest change.  I'd like to
>  call them back and see what else we can do but I'm kind of upset they let me
>  drive the van out of the shop in that condition.  Anyway, can this small
>  vacuum leak in the throttle body be the cause or is there something else I
>  should be looking at? Is it time to just start replacing parts?
>
>  BTW, I just check the timing and it was dead on the V mark.
>
>  Also, nobody has been able to find the "thump-thump-thump" noise emanating
>  from the rear. 2 places think it "could" be the axel. I can't wait for the
>  tow truck ride to discover what that is....
>
>  Thanks,
>  Bryan
>

--
Neil Nicholson. 1981 Air Cooled Westfalia - "Jaco"

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