1974 BMW 2002 tii

The ’74 2002 Tii uses the mechanical Kugelfischer PL04 continuous-injection pump—great when dialed-in, but it has a few well-known weak spots:

1. Cold-start valve diaphragm cracks → long crank times when cold, fine once warm. (Quick check: clamp the valve hose cold; if idle smooths, replace the valve.)
2. Injector nozzle screen clogs → rough idle, lean misfire. (Back-flush or swap nozzles; keep a spare set.)
3. Control-pressure piston wear → high idle, rich mixture, sooty tailpipe. (Measure 3.2 bar control pressure at 20 °C; rebuild kits are available.)
4. Pump drive belt slips 1 tooth → sudden rich/lean surge, hard hot-restart. (Check tension every 6 months; belt is under the alternator.)
5. Return-pressure valve stuck → flooding after shutdown, hot-start difficult. (Tap the valve body; if no change, rebuild or replace.)

Because your car is already modified, whoever tuned the engine may have tweaked the pump’s fulcrum screw or metering collar—so baseline the pressures first before chasing parts. Good news: every seal, diaphragm and gasket is still available and the pump is rebuildable on the bench with basic tools.

Need part numbers or a how-to on checking control pressure? Or want to see stock Tii’s for comparison? Just let me know!