I have a 86 z28 tpi 305, The car runs rough and won't idle, and the fuel pressure won't go above 20. This is what's been replaced already: fuel filter, PCM, fuel pump, relay, regulator, and an idle air control. What else could it be? Any help would be appreciated.

 

Assuming that the new pump and regulator are OK, you may want to check fuel lines for kinks, rust, or anything that may cause an obstruction. Also check that the pump is getting full voltage when it is working, corroded or damaged wiring and connectors can cause a voltage drop when the pump is working, and the pump won't be able to make full pressure.

 

what's the voltage suppose to read?

 

You should read at least 12 Volt at the pump itself while it is working. Voltage will usually read correctly, even with a bad connection, if the pump is not working. Also, the PCM operates the pump through a relay, so check the relay also.

 

ok, got everything in check, idle was good while in park, then put it into drive and it bogs out like it's not getting any gas. ????