View Single Post
madkow madkow is offline
Join Date: Dec 2006
Posts: 63
Question Shimming Fuel Pressure Regulator

I recently had my Fuel Distributor rebuilt to 930 3.3 specifications. It doesn't run well. I later studied my car's history. According to the receipts, about 2 years ago the car was updated to 3.4 liter cylinders. Now today I got my Bosch CIS tester in the mail. I plan to check out the pressure. I strongly believe that the fuel pressure regulator in the fuel distributor was shimmed wrong on my car!

I was reading that to add pressure you need to add shims and to reduce pressure you need to take away shims. Each (.020 in) shim added increases system pressure by about 4 psi. And each taken away will decrease pressure by 4 psi.

I read that if the CIS pressure is too high then the car will run lean. And if the pressure is too low then it will run rich. Is this true?

According to my specs book my 79 930 needs to run a "control pressure" of 3.65 bar + - 0.20

"full throttle enrichment" 2.9 bar + - 0.20

Does my car still run under these specs or will it be different since it is a 3.4 rather than a 3.3?
Old 01-23-2007, 10:38 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #1 (permalink)