Engine turns over but doesn't start. Puff of smoke

Question

This morning I got in my car (Mk3 Golf) and went to start it. The engine will turn over indefinitely but not start.

On my second attempt, again it would turn over, but as soon as I let go of the key it would stop and let out a big puff of smoke. The smoke (from what I can tell) is coming roughly from the area near the cam belt cover and the top of the block (not sure what else to be looking for around here and terminology. I want to say carburettor?)

I've checked the HT leads and distributor and they look fine. I've also been told it could be the coil. I'm a bit lost though at this point and any suggestions would be much appreciated!

theUg · Accepted Answer

I had similar issues with American-spec 2.0 ABA motor. Now that you had clarified that it still occasionally starts, broken timing belt is not the issue. The proper tune-up, however, might be in order.

The problem I had was due to the fact that my spark plug wires were worn, and reacted poorly to damp environment. More likely, because of deteriorated insulation with micro-cracks through which moisture could come in contact with the leads and cause shorting. I would have trouble starting in wet weather, and after a car wash it would not start for an hour at its worst.

While the new wires could be all that is needed, full tune-up kit, including distributor cap and rotor, should not be very expensive, and it is a good idea to replace those parts. I would not, however buy the new coil until you see if the tune-up kit rectifies the problem, or, otherwise, I would still check if it operates properly before you start replacing half of your engine compartment. Check the battery as well, while you’re at it.

Nick C · Answer

To start a petrol engine you need three basic things - compression, fuel and spark. If it won't start, you're probably missing one or more of these.

Does it sound normal when you turn it over, or does it spin excessively slow or fast?

Immediately after trying to start it, smell the area around the exhaust. Can you smell unburnt fuel?

The big puff of smoke from the top of the engine sounds concerning. It sounds like it's coming from the inlet side around the injector area? Does it look like oily smoke (black or blue), steam (white) or fuel vapour? Smell might also help here, but be caseful in case it is hot!

What does the oil look like? Pull the dipstick, and check for a thick fluid of mayonnaise-like appearance. Does it look like there is oil in the coolant?

HT systems have a habit of failing whil still looking fine. To test that, remove one of the plug leads, and attach it to a spare spark plug. Lay the plug on the top of the engine, so that the threaded bit of the plug is in contact with an unpainted bit of engine. Try to start it, and watch the plug to see if there is a strong spark.

Engine turns over but doesn't start. Puff of smoke

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