Hi Mike, I did a write up on this a few years ago. Since I have the91 digifant, the hoses are the bugger of a difference. I recall though a recent thread where the Correct hose connections was the topic for the digijet systems, that might be a good search to. My main approach, was to tee off of the plenum for the fuel pressure regulator, digifant has one hose to the PR. Once the tee is up and going with your Harbor freight gage you can look for leaks. My first choice is to utilize a pair of needle nose pliers and gently squeeze the vacuum lines closed and observe the gage reaction. I try to visualize the system like a tree and branches, so start at the source and then follow from there. The second check is the carb cleaner with a straw. Not for the squeamish. Some pooh pooh the concern but... be prepared with any precautions related to spritzing or spraying a flammable onto a running engine. Ok to proceed again start with the plenum seals, then down to the individual rrunners at the cylinders. The seal on the fuel injector bases, the runner seals and the seal on the throttle body. Additionally the plenum hose barbs that supply the brake booster and the vacuum tubes. This should get you a long ways to testing the manifold vacuum. As to numbers. 12-14 at 840rpm idle is normal, depending on your timing, compression etc. I'm a digester so pmail me too if you have a questions. Mark
Date: Wed, 24 Oct 2007 16:15:29 -0700 From: "Mike \"Rocket J Squirrel\" Elliott" <camping.elliott@GMAIL.COM> Subject: Manifold measuring - is this right? Hi, I'm looking for leaks in the intake manifold. Bentley's doesn't give a procedure for checking intake manifold vacuum so I'm winging it. I let the engine warm up so that aux air regulator thing is closed, and then I pulled one of the hoses going to the vacuum unit on the dizzie and connected it to my fine Harbor Freight vacuum gauge. This is a 1.9L engine and the hose I'm using is the hose labeled "2" on the left hand photo on page 24.25 in Bentleys.I don't know how appropriate this hose is, but it has fewer bits connected to it than the other one. There's also a hose going to the fuel pressure regulator, maybe it's a better choice? ANYWAYS, when the hose is disconnected from the vacuum unit, the idle hunts up and down. The vacuum gauge shows around 18psi -- depending on engine rpms. I can open the throttle and the vacuum might drop to 10psi, then climb back up . . . I really have no idea how one goes about measuring vacuum. -- Mike "Rocket J Squirrel" Elliott 71 Type 2: the Wonderbus 84 Westfalia: Mellow Yellow ("The Electrical Banana") 74 Utility Trailer. Ladybug Trailer, Inc., San Juan Capistrano KG6RCR |
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