Got an issue with cold starting of my 1993 RS1800 and using the code reader i had 2 issues, 1 was the engine coolant sensor which have replaced and the other error 556 electric circuit of fuel pump but not sure what to look for. There is a fuel pump relay in fusebox but the fuel pump is running constant and not switching off after 3 sec when i just turn ignition on.

Any help would be appreciated

 

Try a new relay.

 

This is just an educated guess but I would look at the fuel pressure side of things.