yamman35 Posted April 23, 2016 Share Posted April 23, 2016 I have a 1999 TD5 defender. It won't start. I have replaced the fuel relay but the pump works if the relay is manually held down. The pump does not start when the ignition is turned on. The nanocom shows ambient air circuit fault. When the engine is turning over on the starter, the nanocom shows no RPM. Is this normal? If the crank position sensor is faulty will it stop the ECU from turning on the fuel pump relay? Is there another fault or scenario where the ECU turns off the fuel pump. Quote Link to comment Share on other sites More sharing options...
Farmerfred Posted April 24, 2016 Share Posted April 24, 2016 You'll need someone to hook up a diagnostic fault reader and go from there. My Brother had a fault reading relating to the crank sensor and the symptoms were the same, it turned out that it was the starter motor that was faulty, starter replaced, problem cured. Quote Link to comment Share on other sites More sharing options...
dave88sw Posted April 25, 2016 Share Posted April 25, 2016 The nanocom should see an RPM signal when cranking. However, you should still get the 30 (ish) seconds of fuel pump priming when the ignition is switched on. As above, the starter can interrupt the signal from the crank sensor (they can arc internally and due to the proximity of the crank sensor wiring, the arcing can interrupt the signal to the ecu), if this is the case, it should run with a bump start. Do you have any other issues? I've known a few TD5 Defenders now that have had a poor earth in the underseat ecu box, this has prevented the car from starting but it was accompanied by a buzzing relay and the dash warning lamps came and went as they felt like it. Hope that helps Quote Link to comment Share on other sites More sharing options...
V8 Freak Posted April 26, 2016 Share Posted April 26, 2016 Just a wild thought... Try depressing / resetting the impact switch on the bulkhead. I can't remember what it stops apart from the engine (of course), but it would make sense to not pump fuel after an impact is detected... I've disconnected mine to crank for oil pressure before now so the engine will crank if it's tripped.... Worth a try? Other than that replace the crank sensor... Neil Quote Link to comment Share on other sites More sharing options...
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