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Fuel Injection


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  • The 1975 Opels came factory-equipped with Bosch LE-Jetronic Fuel Injection systems, which added a moderate amount of power output. Most OMC Tech articles concern maintenance and repair of the 1975 systems. These are not to be confused with the later European Motronic Fuel Injection systems, which, when mounted on classic Opels, produce far greater power. Before installing fuel injection on a carbureted Opel, consult experts with FI experience for advice and a list of required parts and complete installation instructions.

How to Order: Reprints of Individual OMC Blitz issues, can be ordered by mail from the OMC Treasurer (3824 Franklin Ave, La Crescenta CA 91214) for $2.00 each (cost includes postage). This offer is subject to availability.

Mar 2002

1975 Fuel Injection Problems, 1 page (illustrated)
Identification of more common problem components such as vacuum hoses and bakelite injector mount plates, with suggestion that replacement of parts (as they are suspected of malfunction) will add up (eventually) to a more reliable system.

Sept 2000

Cleaning Fuel Injectors, 1 page
Recommendation of RC Engineering in Torrance, CA for FI part service.

Aug 1999

Bosch L-Jetronic fuel injection diagnosis, 2 pages (illustrated)
Illustration (fair quality) visually identifies stock 1975 Opel fuelinjection system components and a checklist helps to diagnoselikely circumstances causing various system operation problems.

April 1999

1975 Opel Bosch L Jetronic FI "Brain Box" Interchanges, 1 page
List of a number of possible sources for replacement of a 1975-type Bosch L-Jetronic "brain boxes," (List includes 1968-73 VW, Porsche 912E, 1973-1975 Porsche 914 (2.0 liter), 1970-73 Porsche 914 (1.7L).) NOTE: Some adaptation may be required, and writer did not test FI units. Please consult a trained FI mechanic, before installing these boxes!

Oct 1996

Tip on Parts Sources, 1 page
Tony D. mentions alternative car model sources for FI parts: EFI relay, fuel pump and resistor block, from Datsun 280Z (through 1978 model year), and fuel pressure regulator and deceleration valve from the Porsche 924 (L-Jetronic version).

July 1995

Installing Fuel Injection in a GT Notes; 1 page
Steps listed include: Acquiring FI system, with specialized radiator hoses, dual-thermostat housing and hoses, FI high-pressure fuel pump and fuel pressure regulator, FI high-pressure fuel hose lines, FI fuel filter and FI air filter and adaptor. FI Exhaust manifold is preferred, or you can "cap" the stock manifold with a square plate. You need to remove the passenger-side hood bracket and shorten the pivoting latch bar. The FI computer box is remounted in the passenger side footwell. Throttle cable and bracket are custom-mounted on the firewall, and the FI injectors should be cleaned, balanced and flow-tested. It is also strongly suggested that you consult an Opel specialist with specific FI experience, prior to doing an FI installation.

July 1995

Diagnosis of 1975 Manta FI problem, 1 page
Rick G. notes, that loose wiring of the FI relay in a 1975 Manta, caused his engine to stall, then mis-wiring on the repair (from the relay to the starter solenoid) caused the engine to fill with fuel. He suggests checking all color-coded FI wires to the factory shematics.

May 1992

Opel Fuel Injection: General Explanation of Components; 3 pages (illustrations)
Condensed reprint, of the introductary section to the 1975 Opel fuel injection system from the 1975 Opel Factory Service Manual Supplement (purple cover), which describes function of individual FI components: Control Unit (a.k.a. "Brain Box), Air Flow Meter, Throttle Valve Switch, Coolant Temperature Sensor, Fuel Injectors, Cold Start Injector, Pre-Resistors, Thermo-Time Switch, Auxiliary Air Valve, Fuel Pressure Regulator, Deceleration Valve and Dual Relay (Bosch L-Jetronic system).

Dec 1989

Manta/Ascona Tip: 1975 Fuel Injection Leaking Fuel Line Replacement Parts; 1 page

Sept 1987

Opel Factory Service Bulletins (1975 Fuel Injection Problems); 1 page
Opel FSB #75-I-14 (5/6/1976 and #75-I-15 (12/13/1976) concern replacement fuel injectors for 1975 Opels with a green colored connector (part #90018023), which should not be cleaned per prior factory service bulletin #75-I-08, but instead should be cleaned by adding a can of GM Top Engine cleaner (part #1050002) to the fuel tank when it is less than 1/4 full.

July 1987

Opel Factory Service Bulletin (1975 Fuel Injection Poor Performance); 2 pages
Opel FSB #75-I-08 (9/30/1975) concerns disassembly and soaking of 1975 Opel fuel injector tips in Dupont metal conditioner solvent to remove rust deposits caused by cheap corrosive non-detergent gasoline.

Feb 1987

"BMW Fuel Injection" by Blanton, Rowe & Williamson. Book Review of Bosch's L-Jetronic Fuel Injection System (Similar to 1975 Opels); 3 pages.
The book covers each individual FI component's functions, and offers tips on adjustment of each, to compensate for performance loss from normal engine wear.

Jan 1987

Parts Required to Install 1975 Fuel Injection (on pre-'75 Opels); 1 page
Gil W. notes parts needed: 1975 or later exhaust manifold, 1975 high-pressure fuel pump, matched injector nozzles, and exhaust valves (suggests Opel part #8960421 or equivalent) for best results.

Dec 1986

Opel Factory service Bulletin (1975 Fuel Injection Airflow Meter & Idle); 1 page
Opel FSB #75-T-4 (3/21/1977) suggests cleaning air flow meter hinge with WD-40 type lubricant, adjusting air screw to bottom and back out 3 1/2 turns to factory setting, and verifying specified output of the air flow meter terminals with an ohm meter (range between 6 & 7 = 40 to 300 ohms, between 6 & 8 = 130 to 260 ohms, between 6 & 9 = 200 to 400 ohms, between 7 & 8 = 100 to 500 ohms, and between 8 & 9 = 70 to 140 ohms).

Nov 1986

Opel Factory Service Bulletin (1975 Fuel Injection Control Unit); 1 page
Opel FSB #75-I-16 (2-14-1977) illustrates the 35-terminal and 26-terminal styles of fuel injection "brain box" control units used on 1975 Opels.

Dec 1985

Can 1975 Fuel Injection be Legally Replaced in California?; 1 page
Notes that the California "Smog" restrictions prevent substitution of 1975 fuel injection system with a carburetor, unless it can be proven that the FI components are no longer available or sold by approved vendors.

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