Cranking But Not Starting

[PUGPIRATE 0]

When cranking, can you smell petrol out of the exhaust?

You say it nearly starts, there is a spark, the fuel pump is working. If you get a stink out the exhaust the injectors are firing, so all the ingredients are there for it to work... indicating maybe it's a mixture problem? I would be looking at the connections to the AFM and engine temperature sensor, have you tested continuity from these back to the ECU plug?

 

Ignition components could also be responsible, even if you get a flash from the timing strobe the spark may be weak - have you actually checked the condition of the dizzy cap and leads closely?

 

Otherwise I would be reduced to checking every ecu pin is continuous to its respective connector a the other end, cos you seen to have covered most of it already.

 

Thanks for the reply. Haven't noticed any unusual petrol odours but I'll an eye (or a nose) out for that. Distributor seems OK - I swapped it for a spare earlier today and it made no difference. Distributor cap and rotor arm are pretty new and still look it - outside and in. I tested the lead from the distributor to the ignition amp and that seems fine too. It wouldn't surprise me if was ignition related as it was horsing around with an ignition lead that landed me in this trouble in the first place. The car has otherwise been working great until I started poking around!

 

I guess I'm going to have to do a lot of work with my voltmeter this weekend!

Edited August 20, 2011 by PUGPIRATE

[PUGPIRATE 0]

It's pouring down outside today so I had a look at the wires coming from the ECU to see if there were any unusual voltages present. One major problem is the fact the wires don't seem to be numbered.

 

I disconnected the starter and turned on the ignition and went through the wires one by one. One curiosity was the thin gauge orange wire. This showed just under 5V - even if I turned the key all the way. Is this normal, do you think? I associate the colour orange with ignition so it looks promising but the lack of a wire number means I have no idea what it does. And bear in mind that the engine wasn't actually running.

 

Input would be appreciated as always.

[PUGPIRATE 0]

I obtained a range of voltage readings from the wiring loom that goes into the ECU, many of which seem odd. These voltages were all taken with the ignition switched on and starter disconnected. I don't know what they should read under normal circumstances so I'm hoping that one of you bright sparks will see an obvious clue in this data.

 

Thin Gauge Blue Wire - 6.49V (goes to 11.91V when key turned all the way - i.e. when cranking)

Medium Gauge Blue Wire - 11.74V

Heavy Gauge Blue Wire - 0.5V

 

Thin Gauge White Wire - 5.52V

Medium Gauge White Wire - 11.89V

 

Thin Gauge Red Wire - 0.17V

 

Thick black wire with thin green wire in core - 12.05V

 

Thin Gauge Yellow Wire - 1.68V

 

Thin Gauge Brown Wire - 0.02V

 

Grey/Off White Wire - 7.66V

 

Orange Wire - 4.48V

[PUGPIRATE 0]

Okay. I believed that I've identified most of the wires from the ECU. Hoping that this data will help isolate the problem. These are the voltages on each wire when the ignition is switched on (starter disconnected)e

 

ECU WIRING

 

STARTER - 6.49V goes to 11.91V when cranking (Thin Blue Wire)

FUEL INJECTION - 11.74V (Medium Gauge Blue Wire)

UNKNOWN (not in engine bay) - 0.5V (Heavy Gauge Blue Wire)

UNKNOWN - 5.52V - Thin Gauge White Wire (this progressively increased in voltage to 10V)

FUEL PUMP RELAY - 11.89V

THROTTLE SWITCH - 0.17V (Red Wire)

THROTTLE SWITCH - 0.02V (Brown)

IGNITION COIL - 12.05V (Black Wire)

AFM - 1.68V (Yellow Wire)

AFM - 7.66V (Grey/Off-White)

SENSOR (TEMP?) - 4.48V

 

 

IGNITION COIL

This seems to be getting a good 12V as this was measured on each of the four pins on the connector.

 

AFM

WHITE WIRE - 11.75V

EARTH

YELLOW WIRE - 1.68V

GREY/WHITE - 7.66V

 

IGNITION MODULE

 

I measured 12V on two of the pins here.

 

Do any of these measurements offer any insights as to why my car won't start?

Edited August 20, 2011 by PUGPIRATE

[PUGPIRATE 0]

Well, gave the engine and wiring a thorough clean, put it back together and things improved slightly.

 

The car would start - briefly - and would keep running only if I kept the revs up by putting my foot on the accelerator. After a few minutes of this (hoping that it would 'clear' the problem) I stopped and had a look at the ground under the engine. There was a small puddle of coolant.

 

I undid the nuts on the inlet manifold a little then re-tightened progressively - making them very tight indeed. I then started the car again and kept the revs up. Still refusing to idle. Now white smoke was emerging from the engine bay. I stopped the engine. There was no further sign of coolant leak on the ground and the smoke appears to have come from the back of the engine.

 

I'm thinking that I've damaged the inlet manifold when putting it back on as I had a similar issue a few years back. Would you tend to agree?