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Hi.

My wife recently bought a 1990 Mazda Familia 1500cc with the DOHC motor (apparently theres a another?) and a few days after getting it home it developed this very annoying idling problem where it would drop down to about 300rpm before picking itself back up to about 1500 rpm then dropping again. If left long enough the car would end up stalling sometimes but if you held your foot on the accelerator a bit and held the revs constant for a couple of seconds it would sort itself out.

Today while she was driving it she stalled it and it refused to start. It cranked but wouldn't catch so we let it sit for about 10 mins (luckily it happened on a quiet road!) and tried again but nothing. I decided to try clutch start it and it actually worked though when the engine fired up you would have thought otherwise as it was only idling at about 200rpm and it sounded as if it had a slight miss. I managed to get it home without any issues and decided to change the spark plugs. The plug in the no 1 cylinder had quite a bit of oil on its thread which the others didn't. It actually dripped off! (leaking head gasket?)

Anyway we went to go for a drive to see how it went and as soon as any power is required it cuts out and stops. Even when you push on the accelerator.

Could that be the fuel pump? I did notice a slight smell of petrol after a couple of attempts but that could of been from it stalling 3-4 times in a row?

I'm really not sure where to start looking and I cant even drive it anywhere to have it looked at so any ideas as to what it could possibly be would be great!

Kind regards,

Robert

There are a few things that spring to mind; idle control valves often use a stepper motor and these often give trouble causing the idle to fluctuate. Sometimes a good clean is all it needs but in most cases the stepper motor will need replacing. Other possibilities are a faulty airflow meter, air leak on the intake manifold or rubber intake hose (common problem). A faulty fuel pump will also cause these symptoms.

The oil on the spark plug thread is likely caused from a faulty spark plug tube seal (on the tappet cover).

You should also check when last the cambelt was replaced - might be a good idea to replace it if it hasn't been done recently.

Thanks for the quick reply. I found the cause of the stalling and I feel rather stupid haha. I had taken her air filter cover off to clean the filter and in the process I had disconnected what I'm assuming to be the airflow sensor (or something that was attached to the filter box) and had forgotten to reconnect it.

Cam belt is all good and was only done 10K ago.

Thanks again