Plenum Removed - Now No Secondaries - ZR-1 Net Registry Forums

Bob Eyres · 09-12-2019

We took the plenum off my 91’ to replace the starter. Now the new starter works fine, but the engine falls flat over 3K rpm. We checked the vacuum pump and it wasn’t running at start up. Replaced it, vacuum is good, but still those secondary butterflies won’t open. Got to open the plenum again. What’s the likely culprit?
BTW, the induction has been working fine in it’s stock configuration for 28 years previous to this plenum pull.

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09-12-2019	#1
Bob Eyres Join Date: Jul 2005 Location: Jupiter, Fl. Posts: 813	Plenum Removed - Now No Secondaries We took the plenum off my 91’ to replace the starter. Now the new starter works fine, but the engine falls flat over 3K rpm. We checked the vacuum pump and it wasn’t running at start up. Replaced it, vacuum is good, but still those secondary butterflies won’t open. Got to open the plenum again. What’s the likely culprit? BTW, the induction has been working fine in it’s stock configuration for 28 years previous to this plenum pull. Sent from my iPhone using ZR-1 Net Registry