Technical punto mk1 1242 no current on cranking

[zazza]

I have a punto mk1 75 which i recently took out the engine and replaced it with another 75. I kept the same stuff such as inlet, exhaust, sensors and pulleys and ecu ! On ignition, everything seems to be working perfect, the fuel pump primes for those 5 seconds, and the coils get the current aswell for that same time, but when i crank, nothing happens apart from the starter turning the engine. No current on the coils !! the coils are in perfect working order since ive got another punto (60) and ive been replacing every component that I thought was damaged!

any help please ??

thanks,
neil

 

[fingers99]

Are you using the original ECU?

 

[zazza]

yes im using the ecu that was with the car originally.

 

[fingers99]

Check for spark at the plugs, fuel past the injector (you should see fuel dribbling onto the butterfly when the engine is cranked).

If neither, TDC sensor.

 

[zazza]

Theres no spark at the plug, but theres also no signal coming to the coils during cranking. the coil receives a signal only during ignition, even the injectors and fuel pump. everything is ok on ignition, but when i turn the key to crank the engine, the starter motor turns just fine and even the engine, but there seems to be no current coming onto the injectors pump and coils. Ive changed a lot of tdc sensors and still nothing happens. and the sensors are all fine coz they work on my other 60 !

 

[fingers99]

Ignition switch, perhaps?

Never tried it on a FIAT, but you may be able to trick it by temporarily bridging terminals in the connector block, with the key in proximity to the switch.

 

[flisko]

I have a punto mk1 75 which i recently took out the engine and replaced it with another 75. I kept the same stuff such as inlet, exhaust, sensors and pulleys and ecu ! On ignition, everything seems to be working perfect, the fuel pump primes for those 5 seconds, and the coils get the current aswell for that same time, but when i crank, nothing happens apart from the starter turning the engine. No current on the coils !! the coils are in perfect working order since ive got another punto (60) and ive been replacing every component that I thought was damaged!

any help please ??

thanks,
neil

interesting, didnt knew that sound when turning key is the fuel pump

 

[Elxpunto90]

Are you using same ignition chamber as before if you have different one are you using the same chip to the right key lock or it will be immobilised

 

[blu73]

bit of background maybe of use here... Why did you change engine in first place?

Does CODE light come on and go off again as it should when you turn ignition on?

Sounds simple but have you giggled the main connector on the ecu to make sure its seated properly?

Does sound like classic cranks sensor, have you checked the sensor wiring for continuity back to the ecu?

 

[Noddy]

If none of the above, did you remember the earth strap to the gearbox and the earths at the back of the engine block? (Although does sound like crank sensor).

 

[fingers99]

I think you need to define "signal" and "current". Remember, coils and injector are fired on the negative (earth) side and if no sensible signal from the TDC sensor is received, they'll often be cut (+ and -) after a few seconds anyway. -- Not sure on that ECU, though.

I still suspect TDC sensor or ignition switch.