Hi, l have transplanted a 5.3 engine from a 99 Silverado into an old 69 Austin pickup. I used the engine box and computer. I have had the engine running perfectly till recently but now it has decided not to start. I have 50lb fuel pressure and a good spark at all the plugs. I have no codes on my OBD reader. The engine randomly fires one cylinder or so. I have swapped all the engine sensors ( cam crank map TPS IAT ) for known good ones. It seems as if the computer is not telling the injectors to fire. Is this something l can diagnose. Any help would be extremely useful. Thanks.
Kev

 

Fifty PSI is a little low but it should at least idle. Do you have any noid lights to check if the wiring to the injectors is good? Are the spark plugs fouled?

Rick