CIS DUTY CYCLE AND CO MIXTURE SETTINGS

Continuous injection Saab 900 and Saab 99 cars have fuel lines that run from the fuel distributor to the injectors at each runner on the intake manifold. The way to test the Duty cycle or the CO mixture (oxygen content in the fuel) is to use an analog meter (one with a needle) to view the reading. The needle should toggle back and forth in about the middle of the gauge when the CO setting is correct. The actual CO setting can be adjusted by using a long Allen wrench and inserting it into the small hole between the black rubber bellows and the end of the fuel distributor. If the CO setting has never been adjusted you may have to pop out the small dowel in the hole before being able to access the CO setting screw. By turning the small Allen clockwise or counter clockwise you are effectively changing the upper and lower chamber pressure in the fuel distributor causing more or less fuel to go to the injectors during idle.
READ THIS: It is very common on the CIS cars that have sat around for a while to not start due to a sticking plunger in the fuel distributor. In many cases the car will not crank at all until you remove the fuel distributor and pull the stuck piston out of the bottom, rub it down with WD40 or Vaseline and put it back in the fuel distributor hole and make sure the plunger moves up and down freely. This issue is usually caused by the fuel evaporating leaving a gunk type substance on the plunger hole and on the plunger which will not allow the plunger to move up and down correctly. The plunger has grooves in several locations along its length which are repositioned according to movement of the air plate which is pulled and release by the suction of the valve and piston movement. The more demand and suction applied to the air plate the more the piston is dropped down out of the hole of the fuel distributor which in turn allows more fuel to be distributed to the fuel injectors.
VERY IMPORTANT: The fuel lines that run from the fuel distributor ARE DISCONTINUED BY SAAB and can no longer be purchased period. Some people go to local hydraulic line companies to get them repaired but the success rate is low. Be careful with the lines because they become brittle.

Knowing that the injector lines on the CIS systems are no longer attainable, I found a solution that worked beautifully. I found some Teflon line, 1/4" od, 1/8" id, 1/16" wall thickness. I carefully cut the old line off the barbs and was able to
press the new line onto the barbs. The line held up perfectly. With careful use of a heat gun, the Teflon line can even be formed to shape. (Tip from Aaron Bean)

More On CO adjustment

Any change in the fuel pressure of a Continuous Injection System will cause problems with the Upper and Lower chamber Pressure of the fuel distributor which means that you will have to adjust the CO screw in the front portion of the fuel distributor. Typically the way to adjust the CO is the let the car warm up then adjust the co allen screw Counter-clock-wise until the the idle begins to drop then move it back to the right just a little until the idle goes back up and begins to drop again. Find the mid point and leave it there. A good way to determine if it is correct is to crank up the car and listen to the engine. If the engine idle drops down just after it starts you will likely need to back off the allen screw a little until it no longer does that.\