Fiat Punto Overfuelling

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Wed 12 Feb 2003 10:39
Fiat Punto Overfuelling - bossbeale
Who knows anything about Fiat Punto engine management? It's a 1.1 litre petrol, 8V on an N plate. It is currently overfuelling on tickover and is difficult to start when warm/hot due to excess fuel. The fuel injection warning light is on. Have looked at coolant temp sensor, inlet air temp sensor and throttle pot. All OK. Lamda sensor is working fine (although not sure this does much at tickover). MAP sensor appears to be OK but not exactly sure how to test.

Did wonder if fuel reg pressure is too high but I can't see how the ECU would know about this, hence how would it know to put fuel injection warning light on?

I'm beginning to suspect the ECU but that's a bit drastic!

Any help would be very welcome.

Thanks.
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Wed 12 Feb 2003 14:42
Fiat Punto Overfuelling - Adam Going (Tune-Up)
Hi Boss,

Double check vacuum pipe to MAP sensor, prefferably using a vauum pump - it should hold vacuum indefinitely. If in any doubt, or there is the slightest sign of perishing externally, fit a new piece of vac pipe. Lambda (Oxygen) Sensor is very important at idle, and commonly a problem on Fiats of this age. You really need an oscilloscope to test it, and you should see it switching from 0 volts to 1 volt around 15 times in a 20 second time frame. Check for battery voltage on the Lambda Sensor heater wire, two good earths, and output on the signal wire. If switching is slow, or output is constant, once fully hot, change the Sensor.

HTH, Adam
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Wed 12 Feb 2003 16:44
Fiat Punto Overfuelling - bossbeale
Adam

Thanks for the response. I'll check out what you suggest.

Thanks again.

Graham
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