Discussion
Pull an HT lead off and rest it on a nice clean bit of alloy, like the plenum chamber. Crank the engine. See a nice regular blue spark? If not, you have an ignition problem.
Remove the air hose from the outlet side of the airflow meter. Turn ignition on, stick your fingers in the airflow meter and move the flap (it swings sideways). The fuel pump should run as long as you hold the flap lifted. The pump may be very quiet and require an assistant to listen for: it's just in front of the offside rear wheelarch (on a V8) or nearside arch on a V6. If you can hear the pump and you have sparks, you may have low fuel pressure or an ECU problem that is preventing the injectors from firing.
To see if the injectors are firing, turn ignition on when it's nice and quiet. Quickly flick the throttle open by hand and see if you can hear a quick 'tick' as all the injectors fire. The ECU doesn't know the engine isn't running but thinks you've just asked for full welly so it fires all the injectors (like the accelerator pump on a carb.).
If there's no tick, try several times more, at different throttle openings. No tick isn't conclusive but it may well point to a non-firing ECU.
Try unplugging and replugging the ECU: sometimes the latch isn't very good on the ECU connector. Check the coolant temperature sensor and airflow meter are connected properly (in fact do these and the ECU connector before trying anything else). Make sure there's a good earth between battery and engine as the injection is earthed to the engine and not the chassis. Check the ignition trigger lead (white/black wire) that runs from the distributor to the ECU round the left side of the engine bay. There's usually a bullet connector in this wire somewhere around the airflow meter than will kill the injection if it corrodes. A dead ignition amp or unconnected HT coil will also prevent the injection from triggering.
After this you're into proper diagnostics with fuel pressure gauges, multimeters, 'scopes etc.... or swapping parts from a known good car.
HTH
wedg1e said:
Pull an HT lead off and rest it on a nice clean bit of alloy, like the plenum chamber. Crank the engine. See a nice regular blue spark? If not, you have an ignition problem.
Remove the air hose from the outlet side of the airflow meter. Turn ignition on, stick your fingers in the airflow meter and move the flap (it swings sideways). The fuel pump should run as long as you hold the flap lifted. The pump may be very quiet and require an assistant to listen for: it's just in front of the offside rear wheelarch (on a V8) or nearside arch on a V6. If you can hear the pump and you have sparks, you may have low fuel pressure or an ECU problem that is preventing the injectors from firing.
To see if the injectors are firing, turn ignition on when it's nice and quiet. Quickly flick the throttle open by hand and see if you can hear a quick 'tick' as all the injectors fire. The ECU doesn't know the engine isn't running but thinks you've just asked for full welly so it fires all the injectors (like the accelerator pump on a carb.).
If there's no tick, try several times more, at different throttle openings. No tick isn't conclusive but it may well point to a non-firing ECU.
Try unplugging and replugging the ECU: sometimes the latch isn't very good on the ECU connector. Check the coolant temperature sensor and airflow meter are connected properly (in fact do these and the ECU connector before trying anything else). Make sure there's a good earth between battery and engine as the injection is earthed to the engine and not the chassis. Check the ignition trigger lead (white/black wire) that runs from the distributor to the ECU round the left side of the engine bay. There's usually a bullet connector in this wire somewhere around the airflow meter than will kill the injection if it corrodes. A dead ignition amp or unconnected HT coil will also prevent the injection from triggering.
After this you're into proper diagnostics with fuel pressure gauges, multimeters, 'scopes etc.... or swapping parts from a known good car.
HTH
Thanx Ian - If it helps I have just re-fitted my dashboard and have been prodding and poking wires from my dash. A couple if fuses dropped off the board and I don't know where they go! Am hoping they belong to the ECU or Fuel pump. I'll also unplug the ECU and re-connect as suggested.
The engine fired then died as soon as I released the key thinking it had started. Then it refused to fire.
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