Odd vacuum pump activity - ZR-1 Net Registry Forums

Jcsws6 · 10-12-2021

I recently picked up a clean 90 which has been working near flawless. I noticed tonight when I moved it the vacuum pump didn't coming on. Previously, it was cycling for the first 5 seconds or so just like my 91. After verifying voltage and the pump, I found that if I unplug the airline it runs. If I've had it unplugged with the car off it will cycle for a second or so then turn off. It has plenty of built up vacuum when I pull it off (noticeable pop). Is it possible the one way valve has become clogged or could it just be holding vacuum?

I'm about to do the fuel pumps and so maybe this is a sign to just pull the plenum and do the injectors as well.

10-12-2021	#1
Jcsws6 Join Date: May 2021 Location: Freeburg IL Posts: 53	Odd vacuum pump activity I recently picked up a clean 90 which has been working near flawless. I noticed tonight when I moved it the vacuum pump didn't coming on. Previously, it was cycling for the first 5 seconds or so just like my 91. After verifying voltage and the pump, I found that if I unplug the airline it runs. If I've had it unplugged with the car off it will cycle for a second or so then turn off. It has plenty of built up vacuum when I pull it off (noticeable pop). Is it possible the one way valve has become clogged or could it just be holding vacuum? I'm about to do the fuel pumps and so maybe this is a sign to just pull the plenum and do the injectors as well.