'93 Vacuum Failure

[rwmcarlyle]

When the mercury goes below 10 degrees I find my vacuum boost fails at lower RPM. I'm guessing that the pump is weak. Could be leaks elswhere. Anybody run into this? Also any info on vacuum pump sources?



Thanks

RWC

 

[JLEONARD]

I had the same issue on my 91 with the diaphram pumps. I found one plastic T with a very tiny crack. Replaced that and it was better but not solved.

I believe it was the booster going south but sold the truck with the mystery unsolved.