Blazer codes 171 and 174

[Nandy]

I changed the fuel pressure regulator for this vehicle. If you want some of the background of that you can see this thread: http://forums.iboats.com/showthread.php?t=296332

In a nutshell, I changed the regulator and now I am getting codes 171 and 174, they come and go... I did disconnect the injectors when I pulled it out. But I dont see how that is going to make the blazer run lean. I might have a gas pump problems but I also would not think that contributes to these codes.
If anyone can give me an advise to what I need to look next I will appreciate it.

Thanks...

 

[lowkee]

Re: Blazer codes 171 and 174

Hmm, try this:

One of the most common causes of Ford P0171 and P0174 lean codes is a dirty mass airflow (MAF) sensor. The MAF sensor is located in the air inlet tube
just ahead of the throttle body. The MAF sensor should be protected from outside dust and debris by the air filter, but sometimes the air filter doesn't fit real tight inside the housing and allows unfiltered air into the engine. Dirt can stick to the MAF sensor wire and form a coating that slows the response of the sensor to changes in airflow. The MAF sensor can also be contaminated by fuel vapors that back up through the intake manifold and throttle body when the engine is shut off. The vapors can leave a waxy coating on the sensor wire. This causes the MAF sensor to under report airflow, which in turn misleads the powertrain control module (PCM) so it doesn't add enough fuel to maintain a properly balanced air/fuel ratio. As a result, the engine runs lean and sets a P0171 and/or P0174 code

It appears Chevy and Ford use the same computer, as the error codes are the same on both. This is from a Ford Windstar forum, but seems to fit most anything.

Also found this on a Blazer forum:

I will recheck fuel pressure after engine gets hot. It is an Airtex fuel pump. By the way, I failed to mention that I did get two error codes a week ago P0171 and P0174. It is my belief that these error codes were the result of the low fuel pressure. Am I correct in my thinking?

Yes lean on both banks can be caused by low fuel pressure.
Also on a 97 make sure you run a voltage check on pump to.
97 is a bad year for ign switch problems.
And Airtex fuel pump is also bad news.
Carquest has droped them like a hot sput.
And other parts places are gettin a high come back rate on them.
Only replace with the AC Delco/delphi fuel pump.

If the airtex pump checks bad take it back and make them adjust it on a good AC Delco/delphi fuel pump.
Only about 25 dollars more.
Good Luck and let us know how it goes.

 

[dolluper]

Re: Blazer codes 171 and 174

Cleaning the MAF sensor . I find it's best to take it off and spray it with electronics cleaner or brake cleaner. Make sure you are careful not to damage the MAF sensor, and make sure it's dry before reinstalling
Inspect all vacuum and PCV hoses, replace if necessary
Check for a dirty fuel filter and proper fuel pressure

 

[xtraham]

Re: Blazer codes 171 and 174

171 and 174 are the generic OBDII codes for lean on the left and right banks, replace the fuel pump and fuel filter, clear the codes and it will be fixed

 

[Nandy]

Re: Blazer codes 171 and 174

Cleaned the sensor and made sure all hoses/vacuum looks good. The light went off but it has done that before so we shall see. The maf looked clean, but who knows. I ordered the pump...