97 Suburban that Wont Start

I have a 97 Suburban that refuses to start. its been to the shop two times with different diagnosis. first it was the CPI injection system which got changed for a new one. then it was the ECU which i changed for a salvage one but to no sucess it wont start. what else could it be? it has great spark, new plugs, new cap and rotor. any help is appreciated.

Ignition module? I took mine to Advance Auto and they tested it for free.

Is there a proper fuel supply through the injectors?

“Refuses to start” can mean a lot of things.

Fuel Pressure is normal, fuel pump works. wondering if it has to do with sensors?

You say that it has great spark.

And you say that it has normal fuel pressure. Do you know whether or not the injectors are actually pulsing? If it sparks and it gets fuel - well, then the stuff blows up and the engine runs. Unless there is no compression. Maybe you should check the compression. But you should also find out if the injectors get power. A cheap little “noid light” from an auto parts store can be plugged in to find out if the injectors are getting signal.

ignition module was bad. replaced it and now the computor is giving me a trouble code p1351

For the code 1351 to get set you need this: the engine is started, engine running, and the PCM detected an unexpected “high” voltage condition (over 4.6volts) on the Ignition control module circuit during the CCM test. You may get it over an extended cranking tryout. The high voltage is an evidence of a short, you should check the wiring.