secondary vacuum leak

[gregboydpa]

I own a 1990 ZR1
the secondary vacuum system for use of ?full power? has a leak.
The car won?t turn on the full power.
It?s not the pump as i have properly tested it.
It appears i need to remove the plenum.
I am a new owner and would like help determining why it?s leaking and what i can expect may be the cause??
The car only has 5k miles on it.
Should i replace the injectors while i have the plenum off?
thanks for any help

[DRM500RUBYZR-1]

Yes on the injectors, o rings, gaskets.
All from Jerry's Gaskets.

Purchase a low priced vacuum smoke tester.
This will help you isolate all areas of active leaks for repair.

Find all of the instructions of how to on this forum.

There are other causes of secondary failure.
The Factory Service Manual is a must for proper and logical diagnosis.

Keep us posted of your progress.


Marty

[gregboydpa]

just a question about the replacement injectors
do i order new ones for the 90-92 injectors or should i get new ones for the 93-94 injectors

[tccrab]

Originally Posted by gregboydpa

just a question about the replacement injectors
do i order new ones for the 90-92 injectors or should i get new ones for the 93-94 injectors

You must use the 90-92 injectors.
They are slightly different due to changes in the head design between the 375 horsepower LT5 and the 405 horsepower.

You have choices with injectors, if money is no object then the RC injectors will work just fine. At twice the price..... Are they worth it, who knows....
FIC sell good injectors at a decent price.
I personally have had the Accell injectors in my 90 for the last 15 years or so and I have no reason to complain at all. The do require a slight mod to work in our motors, you must cut off a tab on the connector, but it only takes a few minutes to do, so don't be afraid to use them.
Under NO circumstances purchase the original Multec injectors.
They are junk.
Always were, always will be.
they were designed before ethanol was in gasoline, and they fail because of it.
Not if, or maybe, just when.
If you are a NCRS kind of person, the FICs look nearly identical to stock and will pass inspection by even the most anal judge.

Good luck, and don't be afraid to post up any questions during the process.
The plenum pull is a rite of passage for all LT5 owners.

Crabs
'90 ZR-1 #792