1996 Blazer. P0131, P0151 and P0303 were found when using my code reader. What would cause this.

The engine is also very low in power whenaccelerating. Sometimes from a dead stop the engine doesnt wanna move. It idles rough, lacks power and when stepping on the throttle it at times doesnt move, the enginealmost sounds like it isnt timed right when accelerating.

I have put in new AC plugs, (factory ones) wires, cap and new fuel filter. None of this helped.

Took it in to a couple of area mechanics and all of the sensors were working fine for them when they had the scanner on, they couldn't come to a conclusion what was causing it.

I looked into the carburetor looking thing, whatever its called and it appears wet underneath there. Could all of this trouble I am having is the fuel regulator? Could a bad fuel regualtor cause the codes mentioned above?

When a fuel guage is hooked to it, engine off, I get a max reading of 57 PSI and after 25 minutes its down to about 45 PSI. Never ever have a problem with the engine starting. Starts right up all of the time.

Please help.

 

P0131 - O2 Sensor Circuit Low Voltage (B1S1)
P0151 - O2 Sensor Circuit Low Voltage (B2S1)
P0303 - Cylinder 3 Misfire Detected

I would check the grounds on the back of the cylinder head as well as the main PCM ground. It is possible that the PCM is getting intermittent ground to the O2 sensors causing the problem. I would also inspect all of the connections to the O2 sensors.

From your other thread on this subject (Misfire 0303, engine loses power), I can see that you have been having this miss fire issue for awhile... I too would suspect the O2 sensors. How did the mechanics determine that the O2 sensors were fine? What brand O2 sensors are in it?

If you do replace them, do yourself a favor and replace them with genuine AC Delco sensors. I have had nothing but bad luck with Bosch & Denso (the two main stream aftermarket sensors) in GM vehicles.

 

Looking at the service info on your truck, Swartlkk is pretty much right on. The other thing I would add which is in the service info for all three codes is do a fuel pressure test.

 

Thanks all for the replies, I am not sure what brand the o2 sensors are. Or for that matter, how long they have been in there. Is there a way to test the o2 sensorwith a volt meter or ohm meter?

Filstoy, When a fuel guage is hooked to it, engine off, I get a max reading of 57 PSI and after 25 minutes its down to about 45 PSI. Is this normal? Never ever have a problem with the engine starting. Starts right up all of the time.

Thanks again for the help.

 

As far as I know the mechanics determined the o2 sensors were fine by what the readings were when they were scanning the computer with there machine.

I just recently installed a new engine in this Blazer and it very well could be the grounds in the back of the head. How the Blazer ran before with the old engine I don't know cause the engine was blown when I bought it for $500.

This is the first time that I got a p0131 and a p0151 code. Before it was only a p0303, which keeps coming back to haunt me. I was accelerating kinda hard when the o2 sensor codes came on.

I am trying to give you as much info. asI can so you can help me solve this annoying problem. Hope I don't seem to long winded.

 

It could be the fuel pressure regulator, but also a stuck open fuel injector poppet or o-ring seal in the spider. But since the pressure only gets to 45psi on the low end you should also maybe check the Evaporative emissions system...also there is a pressure sensor in the fuel tank...

 

This is the service info for a1996 Blazer 4.3 I have the whole fuel pressure diagnostic table in a htm file but I can't figure out how to post it here.

Test Description The numbers below refer to the step numbers on the diagnostic table. [ol]Wrap a shop towel around the fuel pressure connection to absorb any small amount of fuel leakage that may occur when installing the fuel pressure gauge. Turn ON the ignition, the fuel pressure should be 415-455kPa (60-66psi). This pressure is controlled by a spring pressure within the regulator assembly. The fuel pressure that continues to fall is caused by one of the following items:[*]The in-tank fuel pump check valve not holding.[*]A partially disconnected fuel pulse dampener (pulsator).[*]The fuel pressure regulator valve leaking.[*]The central SFI injector and poppet valves leaking. [/ol] [ol]When the engine is idling, the manifold pressure is low (high vacuum) and is applied to the fuel pressure regulator diaphragm. This will offset the spring and result in a lower fuel pressure. This idle pressure will very somewhat depending on the barometric pressure; however, the pressure idling should be less indicating the pressure regulator control. The fuel pressure less than 415kPa (60psi) falls into the following 3 areas:[*]A regulated pressure but less than 415kPa (60psi). Amount of fuel to injector OK, but pressure is too low. System will run lean and may set a DTC. Also, hard starting cold and overall poor performance or may not start at all. Refer to Engine Cranks but Does Not Run[*]A restricted flow causing pressure drop -- Normally, a vehicle with a fuel pressure of less than 300kPa (44psi) at idle is undrivable. However, if the pressure drop occurs only while driving, the engine will normally surge then stop running as the pressure begins to drop rapidly. This is most likely caused by a restricted fuel line or plugged filter.[*]A leaking or contaminated pressure regulator valve or seat interface may not allow the regulated pressure to be achieved. Refer to Step 3. [/ol] [ol] Notice DO NOT allow the fuel pressure to exceed 517kPa (75psi). Excessive pressure may damage the fuel system. Restricting the fuel return line allows the fuel pressure to build above regulated pressure. With the battery voltage applied to the fuel pump test terminal, the pressure should rise above 420kPa (61psi) as the valve in the return line is partially closed.[/ol][*]
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Thanks for yourhelp everyone. I will look into the fuel issue as soon as I can. Will keep you posted.