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Hello, My 89 XJS (Marelli ignition) is running full rich, smokes badly especially cold start, plugs turn black immediately and then start to fuel foul. Any thoughts on fuel control?
Major vacuum leak? Has the vacuum line to the ECU been damaged or come off? Vac line to the transmission modulator come off?
The XJS is a MAP (Manifold Air Pressure) management system, so it used vacuum as the load signal to the ECU. No vacuum = full throttle and maximum fuel demand.
Hello, My 89 XJS (Marelli ignition) is running full rich, smokes badly especially cold start, plugs turn black immediately and then start to fuel foul. Any thoughts on fuel control?
Does it still run rich once the car is warm?
My 89 Marelli also runs very rich only on cold start, once warm it is ok.