rich on both banks

i had a code come up several times rich on both banks on my 2001 4.3 liter vortecv6. i bought it used several months ago and it came on and went off several times.Any possible solutions as to what would cause this?

i had a code come up several times rich on both banks on my 2001 4.3 liter vortecv6. i bought it used several months ago and it came on and went off several times.Any possible solutions as to what would cause this?

Fuel pressure regulator on its way out, maybe? Fouled plugs, weak spark.
A chilton or haynes book will give a diag flowchart to follow for the codes you have. They're about 20 bucks at the parts store.

check air filter first

Fuel pressure regulator on its way out, maybe? Fouled plugs, weak spark.
A chilton or haynes book will give a diag flowchart to follow for the codes you have. They're about 20 bucks at the parts store.


I changed the plugs cap rotor and fuel filter. Air filter is a month old. I will get fuel pressure regulator checked out.my engine has been pinging/diesling pretty bad lately.

Fuel pressure regulator on its way out, maybe? Fouled plugs, weak spark.
A chilton or haynes book will give a diag flowchart to follow for the codes you have. They're about 20 bucks at the parts store.

yes I to belive it to be the fuel pressure regulator because the code came up on my 01 silverado 4.3 took it to the dealer fixed it and the light went away thank god the proplem is that the regulator and the fuel pump are one unit and the factory part cost about 500$ (not cheap) they also replaced a check valve for another 80$ not sure about that part

i had a code come up several times rich on both banks on my 2001 4.3 liter vortecv6. i bought it used several months ago and it came on and went off several times.Any possible solutions as to what would cause this?

Visually and physically inspect the following items:
- The inlet screen of the mass airflow (MAF) sensor for blockage

- Vacuum hoses for splits, kinks, and proper connections.

- The air intake duct for being collapsed or restricted

- The air filter for being dirty or restricted

- Check for objects blocking the throttle body
Check the HO2S for proper installation.

Check to ensure electrical connectors and wires are secured and not contacting the exhaust system.

Check for excessive fuel in the crankcase.

• Inspect the Evaporative Emissions Control System .

• Test fuel pressure regulator for proper operation.

• Check to ensure that all injectors are functioning properly.

yes I to belive it to be the fuel pressure regulator because the code came up on my 01 silverado 4.3 took it to the dealer fixed it and the light went away thank god the proplem is that the regulator and the fuel pump are one unit and the factory part cost about 500$ (not cheap) they also replaced a check valve for another 80$ not sure about that part

wow! I thought the fuel pressure regulator was on top of the engine around the manifold. I gues it's time to pay the piper.Was your truck running bad also i.e.pinging/clattering?

no I did not noticed anything different about it but when they replaced the parts it kind of did feel a bit more powerful but it could just be me

If you get it narrowed down to fuel or fuel pressure.
Try this check.
Hard to start cold.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
Later V6 and V8 gm engines should have 60-66 fuel pressure.
Cold start should be 64-65 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Do not leave home without it.
Engine running should be 60-66 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak.
Pump leak back fuel pressure reg. leaking or fuel line inside intake.
Post back fuel pressure readings.
MT-2500

wow! I thought the fuel pressure regulator was on top of the engine around the manifold. I gues it's time to pay the piper.Was your truck running bad also i.e.pinging/clattering?


The pump and the guage sending unit are in the tank, and one piece.(GM calls it the fuel "Module") The regualtor is on the drivers side of the intake mainfold, on the fuel rail, with a little vaccuum hose coming off of it. :2cents:

Thanks guys for all the good info! I'm taking it to a local GM shop this weekend.I rather pay the piper and get it fixed right the first time.Thanks again

I agree and make sure it's a factory GM part I belive all there parts come with a 12 month 12k miles warrenty mines did

I took my truck to MacHaik Chevy and they said they couldn't find anything wrong. They checked the fuel preesure and did a engine diagnostic and found nothing but the codes and erased them.They did replace a recall item for my tailgate.The funny thing is they could hear my fuel pump whinning a little but told me not to worry unless it gets hard to start in the morning or staets to stall.What's next I don't know.

Thanksfor posting back and leting us lnow how it went.
You need to keep a eye on it and if the code comes back there is something not right on it.
Get it back in and have them recheck it.
Do you have the code no they erased?
Tip on going to the dealer
Ask that only a factory certified gasoline engine performance specialist work on your car.
Not all dealerships are concerned with how repairs are dispatched, and not all dealership techs bother to take advantage of the training offered by Factory (the vast majority of which is paid training). If the dealer is uncooperative, ask for your money back and call around for a dealer that will accommodate you.
If it gives you any more problems or if the light comes back on let us know.
MT :smile:

Tip on going to the dealer
Ask that only a factory certified gasoline engine performance specialist work on your car.
Not all dealerships are concerned with how repairs are dispatched, and not all dealership techs bother to take advantage of the training offered by Factory (the vast majority of which is paid training). If the dealer is uncooperative, ask for your money back and call around for a dealer that will accommodate you.

This fact is true.
It is important that you become educated and request that the technician that working on your vehicle be 100% trained in the system that he is working on.
Ask for proof of his training certification, the dealer should have the technicians certifications displayed.
Don't confuse ASE certification with GM Certifications.
GM certifications are extremely difficult to meet and maintain.
There are many levels of GM certifications..
Certified Technician - meets all the training requirements for their area of expertise.
Master Technician - meets all the training requirements for their area of expertise and has passed a difficult practial skills test.
GM World Class Technician - these are the BEST GM technicians in the USA..currently there are approximately 600 in the US at this time.
These technicians have succesfully completed all of the GM required training for all service areas, completed the practical skills testing for all these areas and must maintain a 100% completion of all required GM training.

I will definitely take it somewhere else. thanks for the additional info.To have have a vehicle check engine light come on several times,and the service dept. have no clues to what is going on is amazing to me.They didn't charge me anything because they said they couldn't find out what was wrong.unbelieveable!