E30 M3 wont start, help needed!!

Hi Peeps,

I am having a problem where the car turns over but wont start. But unfortunatly it is intermittent, however today it has stopped totally and wont start at all. I was told to try changing the fuel pump and motronic relays as they can be a bit dickie. So did this today, but to no avail.

I have also cheked fuel pump, reg, fuel at rail, spark is fine etc etc etc, all of the usual stuff. Took the three sensors from out of the bellhousing and cleaned those, replaced the earth lead on the alternator, but still no joy. The airflow meter is not stuck and moves freely.

If anyone has any ideas I would love to hear them.

Thanks,

Sean..

Try the following,

Establish if it is fuel or spark that is missing.

Take the coil lead from the dissy cap and hold it with insulated gloves about 10mm away from one of the silver acorn nuts. have someone turn the ignition on and turn the engine over. If you have spark then you are missing fuel. Check the relays behind the water expansion bottle. The fuel relay is usally the one nearest the engine. Look for burned contacts. Replace relay and try again.

You mentioned that you took out the timing sensors located in the gearbox housing. These are quite delicate and moving them side to side can cause them to go faulty. Take a digital multimete and set it to ohms . You should obtain a reading around 950 ohms on each of the 3 sensors arcoss two of the contacts. Without all three sensors working the car will not start. the sensor connectors are located underneath the roundish plastic cover at the top back of the engine.

You can also check that you are getting spark to the plugs by doing the same check as with the plug lead except you need to earth the spark plug. if no spark yet you had it before when you checked the coil lead, then either your plugs, rotor, dissycap or plug leads are faulty. Its a process of elimination.

Hope the above helps.