Ok I have a 2002 Chevy Blazer and the check engine light is on.
I took it to AutoZone today to have them check the codes and they gave me a print out of the codes.
It has the code P0175 which indicates that the bank 2 System is too rich for a predetermined amount of time.
It also has code P0128 which is for the Coolant Thermostat.
There is a secondary DTCs P0172 Fuel Trim System Rich Bank 1.

Ok my thoughts on code P0128 "Coolant Thermostat"
My local Chevy dealer replaced the wire the connects to the Coolant temp sensor on the cylinder head a couple years ago.
Because they said the wire had a short but they didn't replace the Coolant temp sensor itself.
It was running awful and the engine although it runs better after replacing the Coolant sensor still lacks power.
Does it most likely need a new Coolant temp sensor?

What about codes P0175 which indicates that the bank 2 System is too rich for a predetermined amount of time
and the secondary DTCs P0172 Fuel Trim System Rich Bank 1?
They person at AutoZone said the spider fuel injectors might need replaced?
Any advice is appreciated

Fuel pressure is the first thing to check when you have a 172.
Start there.
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Home >> Chevy Truck >> 2002 >> S10/T10 Blazer 2WD V6-4.3L VIN W >> Repair and Diagnosis >> Powertrain Management >> Computers and Control Systems >> Testing and Inspection >> Component Tests and General Diagnostics >> Fuel System Diagnosis

Fuel System Diagnosis

SYSTEM DESCRIPTION
When you turn ON the ignition switch, the powertrain control module (PCM) energizes the fuel pump relay which powers the fuel pump ON. The pump remains ON as long as the engine is cranking or running and the PCM receives reference pulses. If there are no reference pulses, the PCM shuts the fuel pump OFF within 2 seconds after the ignition was switched to the ON position or if the engine stops.

An electric fuel pump pumps the fuel through an in-line filter to the fuel meter body assembly. The pump attaches to the fuel sender assembly inside of the fuel tank. The fuel pump provides fuel pressure above what is needed by the fuel injectors. The pressure regulator keeps the fuel available to the injectors at a regulated pressure. Unused fuel returns to the fuel tank by the fuel return pipe.

TEST DESCRIPTION

Steps 1-3:

Steps 4-11:

Steps 12-16:

Steps 17-23:

2. This step verifies that the fuel pump is operating.
4. This step tests for an internal fuel leak. If the fuel pressure decreases during this test, an internal loss of pressure is indicated.
6. This step tests the fuel pressure regulator. The fuel pressure regulator is controlled by engine vacuum. With engine vacuum applied, the pressure should decrease by the specified value.
8. This step tests for a loss of fuel pressure between the shut-off adapter on the fuel feed pipe and the fuel pump.
9. This step tests for a leaking fuel injector or fuel pressure regulator. If the fuel pressure remains constant during this test, the fuel injectors are not leaking fuel.
12. This step tests for a restricted fuel return pipe. If the fuel pressure is within the specified values, a restriction in the fuel return pipe is indicated.
14. This step determines if the fuel pressure regulator or the fuel pump is the cause of the low fuel pressure. If the pressure rises above the specified value, the fuel pump is OK.
16. This step verifies that a circuit condition is not the cause of a fuel pressure concern. Inspect all fuel pump electrical circuits thoroughly.
18. This step inspects the fuel pressure regulator for a fuel leak from the vacuum port. If fuel leaks from the fuel pressure regulator while the fuel pump is commanded ON, replace the fuel pressure regulator.

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Right, verify fuel pressure. If you have the OE spider injector assy, the poppet injectors are prone to start leaking prematurely.

Now is probably a good time to upgrade the injector assy and do your intake gaskets.

Ok what type of injectors do I need to convert it from OE spider injection assy to a upgraded injector system?

Check the pressure first. If needed you can get a kit.

Not really sure how this determines anything. If its indicated he has low FP, do we know its the spider assy, FPR, or the FP?

He could take the intake plenum off, pull all the poppet injectors out, turn the key on and watch for leaking fuel while he monitors the FP.

There is also a code P0128 which is for the Thermostat.
But I read that code could also be a faulty Coolant Temp Sensor which could make the engine run rich.
I have a appointment with a Mechanic Monday Morning at 9am and he is going to test the Coolant Temp Sensor.

Thermostat is probably sticking open and your engine isn't getting up to temp.

If the engine was running rich due to a faulty coolant sensor or air inlet sensor, you would have a fault code for both banks being rich. Not one.

Well I took my Blazer to a mechanic yesterday and he tested the Coolant temp sensor.
It'* working fine.
He took a infrared heat sensing gun to the engine and told me the engine is running at 165 degrees..
So I'm going to replace the Thermostat myself today.
That should get rid of code P0128.
Could a faulty thermostat cause the engine to run rich?

Absolutely. Your engine burns a lot more gas if the PCM thinks it'* cold.