hi all I have just purchased a 1989 5.3 convertible which has been stood for a couple of years and is giving me a headache. it starts and runs very roughly for a couple of minutes then cuts out as if its flooded. I am still trying to repair some of the problems that came with the car and wondered if anyone has any ideas? it runs rough with a lot of smoke then fades and stops refusing to start until a day or two later? any help as always appreciated

 

How old is the gas ?
If new gas add a couple of cans of Seafoam or Berrymans B12
Check both breathers for rat nest, etc.
Check fuel pump.

 

do you mean te air filters? it has fresh petrol. thanks for te help

 

My first suggestion would be to stop trying to start it just yet. Carefully inspect the fuel injection wiring harness and the connector at each injector. Then I would inspect all the ignition wiring, spark plug cables, distributor, etc.

These components all live in what is sometimes called "Death Valley". It gets quite hot there, and everything deteriorates over time. Replacing all of those items is routine maintenance required at some point.

I wouldn't attempt to start it again until you are certain that you have spark to *every* cylinder and that you know every fuel injector is actuating.

 

Firstly being 89 is it Marelli or Lucas ignition, you can easily tell Marelli by the 2 orange ignition modules on the radiator top support.

Mine did this when it was laid up while being renovated, replacing ALL spark plugs and leads cured the rough running, this is easy (relatively) and the best place to start.

 

My car had exact same symptoms
http://youtu.be/CqHJk3A4q_I
Turned out to be the CTS
(Coolant temperature sensor )
Might be worth checking the resistance on your one or changing it out for new one they're pretty cheap anyway
Willie

 

Injectors operate by grounding. They have positive current whenever the car ignition is on. They are set up in four groups of three. One wire shorted to ground will open three injectors continously and flood. So check those wires in the valley carefully. If they look bad, there is someone on here setting up to do a production run of injector harnesses.
By the way part of the above senerio is that the catilytic converters will start to glow due to the unburned fuel and melt out.