I need help! My oil pressure switch was screwing up, so I went and got a new one, and my idle has been rough for awhile, so I decided to replace the EGR valve, while I was back there. I replaced both with no issues, but now it won't start. It is turning over, but seems like it's not getting gas. I didn't think it would be the EGR but I cleaned the old one, and put it back on, with no luck. The only thing that is different when I turn the car on, is the oil pressure shows as maxed out on the dash (digital dash), when I turn the car on. This happens whether the oil pressure switch is hooked up or not. I diconnected the pressure switch, and it still didn't start. Any ideas?

My Blazer is an '89 4x4 with the 4.3liter, TBI.

 

Did you remove the tbi body to replace the egr? as its the easiest way. One thing i always forget to plug back up is the darn wires to the injectors since they are pushed out of the way.

 

No. I didn't. Or unplug any wires, besides the oil pressure switch. That's what's baffles me.

 

So I figured it out. The Oil Pressure switch, and the Fuel pump are on the same circuit, and the ECM B fuse was blown. Now, my battery is dying. I just bought a new one yesterday, and is dead this morning. Time to trouble shoot again, but at least it runs, may have to disconnect the battery at night, until I figure out what's up.

 

Yea the oil switch and fuel pump work together in a way. Gm build somewhat of a safety feature with it. If it detects no oil pressure through the switch the fuel pump cuts off. to save the engine from running with no pressure.