Fuel Injectors - Testing With VITON Rubber Valve Seats

91saab02

Category
Engine

SECTION PAGE
2 10
ISSUE CODE
03/91-0096 242


Subject: Testing CIS Injectors with
Viton Valve Seats

Application: 1988 900 Models with CIS Fuel Injection


New fuel injectors are available to improve driveability on 1988 900 models with CIS fuel injection (see PSI 08/90-0018). The injectors, P/N 78 56 354, contain a valve seat made of Viton rubber which has improved sealing characteristics to reduce the potential for rest pressure leakage. The Viton rubber seat affects the opening pressures of the injector and requires a revision of the service testing specifications.

Figure 1:

The new injectors can be easily identified by the brass-colored valve tip as well as the Bosch part number 0 437 502 056 stamped on the body of the injector (Fig. 1).

The specifications for testing these injectors are as follows:


Opening Pressure Test

Note

A new injector that has never been used in a vehicle must be flushed on an injector tester before checking otherwise its initial opening pressure may be higher than the specification.

New injector 3.4 - 4.0 bar (50-59 psi)

Note

The test values for opening pressure will change depending on the time interval between injector removal and testing.

Used injector 3.1 bar (45 psi) or higher
(less than 3 hours after removal)

Used injector 3.0 bar (44 psi) or higher
(3 hours - 24 hours after removal)

Used injector 2.8 bar (41 psi) or higher
(more than 1 day after removal)

Leakage Test

No droplets should leak from the injector tip within 120 seconds when at a rest pressure that is 0.3 bar below the opening pressure.

Spray Pattern and Chatter Test

Because of the design of these injectors the previous used tests to evaluate the spray pattern and chatter do not apply.