If there's dirt in the tank, you can plug up a fuel filter in a matter of minutes. As for the EGR valve, MAP, and the other sensors, they are monitored continuously by the PCM and if there's a problem, it will set a DTC in memory and turn the SES light on. As for the fuel pressure regulator: It's actually a pretty simple part:



They rarely have intermittent problems, they're either good or bad. If/when something fails, it needs replacement. They can leak internally past the valve plate, or externally from the vertical green arrow, or from the vacuum connection on the bottom. If the spring breaks, it can't regulate pressure correctly and usually leaks past the valve plate as well. Some, not all, regulators are adjustable. Increasing or decreasing spring pressure on the diaphragm adjusts regulated fuel pressure. When the fuel pressure overcomes the spring pressure, the valve plate opens, fuel pressure drops, and the excess fuel pressure is allowed past the valve plate and returns to the tank. When the spring pressure overcomes the fuel pressure, the valve plate closes, fuel pressure increases, and regulated pressure increases. On 4.3L CMFI and CSFI systems, the vacuum connection on the regulator is exposed to manifold absolute pressure, (no vacuum line is necessary). When the engine is off, or on hard acceleration, little or no vacuum is present which causes regulated fuel pressure to be at its highest. That's why fuel pressure is checked with the engine off. When at idle or decelerating, manifold vacuum increases which causes fuel pressure to drop, (less demand for fuel).

 

The terminal in the fuse box goes directly to the fuel pump module connector. Better check for voltage and ground at the pump module connector.

 

Thanks for the detailed explanation on the regulator. I at least understand that better.
I'm about to start checking connections to the pump. I feel like I'm having to start chasing this gremlin down but man I have burned some calories. I appreciate you all hanging with me on this. I'm sure you're ready to move on other peoples problems.

 

No problem, glad to help, that's why we're here

Disconnect the connector from the pump module. Connect the jumper wire at the fuse panel, described in post #9. The grey wire at the module harness connector should show battery voltage. Both black wires should show less than 5 ohms resistance to ground. Post your results.

 

Okay what I found so far is that I cannot get my hand on top of the tank to even get close to the fuel pump. I will have to drop it in order to get to check connection. But I know there is definitely a problem with the fuel pump or connection because when I banged on the bottom the fuel tank with the jumper wire still in the fuse box it automatically kicks on and start running. The weird part is that now I have no pressure at all on the gauge on the fuel rail. I have not touched it since getting 60 psi on it yesterday afternoon when I started it. Come out today and nothing from the fuel pump and when it runs now nothing at the gauge. Weird,right? What's more weird is that through blazer stared up like there is no problems...with no pressure on the gauge. Maybe Oreillys loaned me a faulty gauge. I don't know.

 

Let me redo that last part so you can understand it. what is weird is that the blazer starts up now like there is no problems... with no pressure showing on the gauge. I removed the gauge and put it back on and started the Blazer and still no pressure.

 

That's the importance of good quality, accurate test equipment. If it's not accurate, it can take you on a wild goose chase and you'll never find the problem. Better get a new tester

Having success banging on the tank is a common symptom of a failing pump motor, but ya gotta have a good tester.

 

I'm assuming the pump module the where the wires plug into the pump. Unless there is a more accessible connector I'm going to see if my wife can reach it later with her small arm and hand. I can't get my hand more than 6" back from the top front of the tank. Looks like the connector/pump is at the top back of tank. I'll let you know what I found out but I'm sure I have a pump connection issue. I just haven't decided at this point if I want to mess with dropping the tank to fix it or just take it to a mechanic at this point. Ill let you know.

 

Dropping the tank isn't difficult, as long as it's not full of fuel If it's a 4 door, be careful of the vent valve in the front corner of the tank when lowering the tank down, it's very fragile. Couple of straps, fuel pressure, return and vent lines, filler neck, and it's out. Whether it's a connection or the pump module, the tank has to come down to fix it. If it turns out to be a faulty pump, use AC Delco or Delphi only, unless you want to be right back in there and do the job again.

 

Will do. I have been in maintenance for 20 years so I've never called a plumber, electrician, or hvac guy out to fix anything in my life. Only been to a mechanic once b/c either I fix it or its a vehicle covered under warranty. I can usually always fix it...and fix it right. So troubleshooting machinery is no big deal for me...usually. We all need help from time to time I guess.