VITON Tipped Fuel Injectors - Checking, Cleaning
91audi04
Group: 25
Number: 91-04
Date: June 30, 1991
Subject: Viton Tipped Fuel Injectors, Checking/Cleaning
Model(s): All with CIS, CIS-E, CIS-E III m.y. 1985-1991
Applies to the following Audi models:
All 4000 1985-1987
All 5000 1985-1987
100 1989-1991
200 1989-1991
80/90 1988-1991
^ check part number stamped on barrel of injector
Note
Two types of fuel injectors are used in these vehicles; Viton tipped, and metal tipped (non-Viton). Viton tipped injectors will have one of the following Bosch part numbers stamped on the body of the injector:
0-437-502-043 High pressure concept, fine thread (replacement)
(Audi Replacement, Part Number: 035 133 551F)
0-437-502-044 High pressure concept, fine thread (OEM)
(Audi Replacement, Part Number: 035 133 551F)
0-437-502-045 Low pressure, coarse thread (replacement)
(Audi Replacement, Part Number: 026 133 551)
0-437-502-046 Low pressure, coarse thread (OEM)
(Audi Replacement, Part Number: 026 133 551)
If one of the above Part Numbers is NOT found
^ refer to Technical Bulletin, Repair Group 25, 91-05 "Metal Tipped Injectors, Cleaning and Checking"
CAUTION
Part numbers are for reference only. Always consult with the Parts Department for the latest information.
Notes regarding Viton tipped injectors:
^ they are available in high and low pressure versions, fine and coarse threads
^ they can be used as a replacement for metal tipped injectors but only in complete sets
^ the fuel absorption characteristics of Viton require different testing considerations than metal tipped injectors
^ spray pattern and chatter tests should not be performed on these injectors because the results cannot be used to determine acceptability
Viton tipped fuel injectors, cleaning/checking
Note
Poor injector performance can often be corrected by flushing and testing the injector using the US 8034 injector tester.
CAUTION
Perform the following checks in sequence.
Corrosion checking
^ visually inspect tip of injector for rust
If YES
^ replace injector
If NO
^ proceed with following procedures
WARNING
Fluid used in tester (Shell mineral spirits 135) is flammable. Do not smoke or have anything in area that can ignite fuel.
Contamination and varnish, checking
^ open US 8034 pressure valve fully by turning counterclockwise
^ loosely connect injector to tester via union nut
^ bleed air from pressure line by operating lever several times, allowing tester fluid to escape through nut use a suitable container under injector to catch overspray
^ tighten union nut
^ slowly operate hand lever
^ approx. 2 strokes per second
^ if pressure does not build up, injector has leakage (e.g. foreign object(s) lodged between seat). If this is the case, proceed to bleeding of injector and repeat contamination test
^ if after bleeding, pressure is restored; return to this point and continue with sequence
^ observe pressure on gauge
^ depending on part number of injector, minimum opening pressure must be:
0-437-502-043 3.2 bar (Audi Replacement, Part Number: 035 133 551F)
0-437-502-044 3.2 bar (Audi Replacement, Part Number: 035 133 551F)
0-437-502-045 2.5 bar (Audi Replacement, Part Number: 026 133 551)
0-437-502-046 2.5 bar (Audi Replacement, Part Number: 026 133 551)
If NO injector may be contaminated or varnished
^ close valve on US 8034
^ flush injector by operating tester with 20 to 30 vigorous strokes
^ open valve on US 8034
^ recheck opening pressure
If still below specification
^ replace injector
If OK
^ close valve on US 8034
^ bleed injector by rapidly operating tester 20 to 30 strokes
^ injector is bled when sound of escaping fluid stabilizes
Opening pressure, checking
^ open valve on US 8034
^ slowly operate hand lever
^ approx. 2 strokes per second
^ observe pressure on gauge
Note
Opening pressure for a Viton tipped injector will vary depending upon how long the Viton has been out of contact with gasoline.
^ use following chart (based on length of time injector has been removed from the fuel system) to determine acceptable opening pressures
Bosch part If less from 3 Greater
number: than 3 to 24 than 24
hours hours hours
0-437-502-043 3.9 bar 3.8 bar 3.6 bar
(Audi Replacement,
Part Number: 035 133 551F)
0-437-502-044 3.9 bar 3.8 bar 3.6 bar
(Audi Replacement,
Part Number: 035 133 551F)
0-437-502-045 3.0 bar 2.9 bar 2.7 bar
(Audi Replacement,
Part Number: 026 133 551)
0-437-502-046 3.0 bar 2.9 bar 2.7 bar
(Audi Replacement,
Part Number: 026 133 551)
Leak checking
Requirement
^ Hand valve on US 8034 must be open
^ using the previously established opening pressure as a reference; slowly increase the pressure to 0.3 bar below that value
^ a droplet may form at the tip of the injector within 15 seconds, however; if the droplet falls off the injector must be replaced
CAUTION
Always flush new injectors before installing, using the US 8034 Tester to remove any foreign material that might have entered the injector during shipping or handling.