Just more info should you be a new owner .....you state it runs fine once started...so when cold...does it burst into life sounding good on all 4 cylinders....but stop after 2/3 seconds...wont re-start...or do you not even get that ?...need to know...as the 5th injector will always get the engine started...its what happens after could be a problem. The 5th injector is controled by the "Thermo timer located rear of engine.."Brown plug"...it has its own internal Heater as well has " Hot water " from engine...which once hot cuts the "negative " circuit to the 5th...as must not activate once engine hot....also if the 5th injector has fault ...not delivering neat fuel...then each time you operate the starter motor a "positive + " is sent to Timer to heat its internal heater...and shut down injector for safety...if your engine does burst into life fine ...but stop...then there is no fault with the 5th....the pressure actuator should take over with a increase in pressure....need to no more. Peter