BMW Tii Fuel Injection Problems

I wish to report a fuel injection problem that I experienced with my 1974 BMW 2002 Tii. Hopefully it's unique as it proved both difficult and expensive to diagnose and repair.

The problem was first picked up at a 16,000 mile major service, when it appeared that the cold start enrichment device was malfunctioning. The device was not decreasing the richness of the fuel mixture as the engine warmed up, requiring unusual and excessive engine temperatures to shut off.

After replacement of the enrichment device, the car exhibited extremely poor gas mileage (13 mpg highway), extreme difficulty starting, easy stalling during the first 15 minutes of operation and a high idle rate (1500-3000 RPM). If the radiator front was totally covered while the engine idled, the engine temperature would increase and after about 10 minutes, the idle rate would decrease as the cold start enrichment device shut off. Idle rates would not drop during normal driving.

The car was taken to Karzundpartz (Greensboro, N.C.) where the problem was corrected.

Casting flash in the passage of the water pump leading to the cold start enrichment device prevented the circulation of water to the device so that the engine temperature was always interpreted as "cold" under normal conditions. Removal of the flash relieved the symptoms and increased gasoline mileage.

I have no idea why the car did not exhibit difficulty immediately upon delivery as the water pump had never been replaced to my knowledge. I do know that before the onset of symptoms my highway gasoline mileage was 23 whereas after correction it is now 30, so evidently the car was defective from the beginning.

Author: L.B. Holt

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Category: Fuel and Exhaust | Related: BMW 2002