Technical backfire HELP

[alexgrfc]

punto 55 n reg 1.1 fire engine i think ,im getting a backfire through the intake ,timing is dead on,replaced sparkplug leads also ingine feels hesitent to rev up ,if i press the pedal slowly and rev it up it seems a bit better but if you dip the pedal in fast it coughs and splutters a bit and backfires,not through exhaust only throug intake any ideas guys ,first post today ,it also failed the emisions test ,thanks for any help

 

[5abr3]

Have you tried inspecting the spark plugs and their leads? I would start there and then look at the injectors.

Also yes the 55 is a 1.1

 

[B3NNETT]

could be something as simple as the plug leads on the wrong way round.
did it on a v6 at work had same symptoms as yours.

 

[alexgrfc]

thanks for the fast reply ,i had the plugs out and cleaned ,i replaced the leads today and all coils are sparking too, you mentioned it could be an injector but this one seems to have only one injector that i can see on the webber injector housing i dont see an injector for each cylinder ,i am new to puntos as i just got this one as a repair project,ive done all its failure probs but dont want to put it back in running the way it is cause its gonna fail its emissions test again if theres unburnt fuel coming through the exhaust

 

[alexgrfc]

any ideas

 

[alexgrfc]

any ideas

?

 

[alexgrfc]

plugs were cracked