Getting bad mileage on my 2002 Monte Carlo LS 3400 SFI 3.4 liter V6 and it is suppose to get 31/22 MPG can you tell me why this may be occurring?

I think you are talking about the solenoid. Watch video

https://www.youtube.com/watch?v=RQuhgOouPUU

It's the reverse process of removing it.

Do It Yourself and DIY Auto Repair by ChiltonDIY

Haynes Manuals

Car Repair Manuals Chilton Haynes Bentley

Uh, the actual firing order is 1 2 3 4 5 6. There should be a sticker under hood that shows proper wire routing to the 3 coilsI need help with the 97 3.1 v6 monte carlo ls firing order?
The firing order goes 1-6-4-3-5-2 im pretty sure im not too familiar with v 6's

How can you tell if you're timing chain need to be replaced?? On my 2002 Monte just keep turning

If the regulator was leaking, the diaphragm may have come apart and may be allowing all fuel to return without building pressure in the rail. Replace the regulator!

1985 Chevrolet Monte Carlo 4.3 liter V-6 VIN "7"
and
1985 Chevrolet Monte Carlo 4.3 liter V-6 VIN "Z"



Hope this helps and just keep in mind that your feedback is important and I'll appreciate your time and consideration if you leave some testimonial comment about this answer.

Thank you for using FixYa.
Jose.

no.

injectors are common so is a bad intake manifold both will cause your problem

The cleaner will not hurt anything. Your motor will just burn it up like fuel. I use the STP (red bottle) because it says on the bottle that it gets rid of condensation in the fuel tank. Condensation (water) does form and collects in the bottom of the gas tank. I use the fuel treatment 3 or 4 times a year and I think it really works. I have a 2001 Monte Carlo that I bought new and it has 177000 miles and it gets 34.5 mpg highway.I have been useing the fuel treatment from the beginning. It has the 3400 V-6.Its basically the same engine you have.
Also you must install a new fuel filter every 30000 miles. The tanks at the gas stations are filthy.
Also check the condition of your air filter and replace at 20000 max.
Transmission filter and oil at each 50-60000 miles.
I hope this info helps you.

The problem might be fuel injectors...