Questions and Answers

BMW 735i Strong Smell Of Petrol Q. Hi Vincent, The car is great but it has a really strong smell of petrol after start up in the morning and is really strong if I open the sun roof or windows. Can you help? Car Details: 1988 BMW 735i 3.5 litre auto 214,000 kilometers Fuel injection ABS P/S, A/C, Cruise control Thanks, Bob

A. The Bosch fuel injection system on this vehicle is equipped with an auxiliary fuel injector which is designed to inject additional fuel into the engine when it's cold to assist with starting and initial warm up idle. Please note that even in the best of conditions you may notice some fuel smell during cold starts, however if it is excessive.

The fuel you are most likely smelling is unburned raw fuel coming out of the exhaust system. I would view the fuel smell as an indicator that your injection system is working as designed but If your spark plugs and wires are older, or of an inferior quality for the car.

It is possible that some of the plugs are fuel fouling when cold thus allowing some measure of unburned fuel to get through your engine until it warms up, and the plugs are then able to fire when the auxiliary injector deactivates.

I Recommend that you ensure that the factory recommended spark plugs and wires are in the vehicle and their condition is good.