I too had the problem with the fuel tank pressurizing while pumping gas, which caused the gas pump nozzle to shut off if I tried to pump gas in any faster than a gentle squeeze at a snails pace. It took forever to put 30 bucks worth in the tank, unless I held the rubber nozzle boot back from the filler neck to allow the gas fumes/vapor to vent out. So... While having an airbag sensor replaced at my local dealership, I asked the tech what he thought the fueling issue was. He told me that it needed the "Vent Solenoid - part number: 25950499" replaced. Which I agreed to have him replace while it was on the hoist. This solenoid was in fact located underneath and in front of the spare tire. I was happy to put that problem out of my head, until the next time I went to the gas station, where I found that the problem was still occurring. This part didn't fix the problem. I was frustrated and didn't bother with going back to complain. Shortly after that, probably a month later I had to change out the fuel pump, located in the fuel tank because it was making a loud whining sound. I had hoped that the fueling issue would magically disappear with the replacement of the fuel pump, even though that wasn't the reason I replaced the pump lol. But it still wouldn't accept fuel without clicking off excessively. Two weeks ago I was doing a little reading here in the blazerforum, and after reading an overwhelming amount of thoughts and opinions regarding the "gas pumping" issue, I decided to order a "Vapor Canister" (Charcoal Canister) from Autozone - part number: VC4113. It cost me $150.84 total, with the free shipping to my front door. it came in 3 days. I installed it the following day. They're located in the left rear bumper panel. I had a quarter of a tank of gas at the time and was dying to find out if it had fixed the problem. Well Wudda Ya Know! It fixed the pumping problem. I was able to lock the nozzle handle and stand there with my hands in my pockets as the tank filled and then clicked off on it's own. I turned on the key and looked at the gauge and was happy to see that it had filled to just above the F. Yay! So that's what it was. I've put gas in a few times since then and it's still filling perfectly without any problem. By the way, I blew into the three ports on the old Vapor Canister and was surprised to find that there was No blockage. I didn't expect to be able to blow into them without finding at least one of them to be plugged. It wasn't the case. I hope this information will help someone else. I know how frustrating it can be to feel as though you're ready to give up and let the dealership bend you over a barrel lol. Good luck.

 

My city mechanic told me that I needed a new evap canister and valve ($120 + $75 installation) and said the Jimmy would not work right without it. My country mechanic on the other hand said that the evap canister system is useless and removed the whole thing except the hose, he secured and inverted that up under the frame. The truck is working fine without it and no more gas smell! Now I might have less fuel economy because of this but I will compensate that with either a cold air intake or by installing an airaid throttle body spacer.

 

WOW. Unless the system was diagnosed properly, which I doubt either one did, they're probably both wrong. If the EVAP system is not repaired properly, the vehicle will not pass an emission inspection, and the SES light will come on. Never mind the Federal fine for tampering with the emission system, which you are ultimately responsible for because it's your vehicle!

Fact: Cold air intake systems and the Airaid TB spacer, are both a total waste of money. There is no improvement in performance, or fuel mileage, with either one.

 

I understand and you're probably right, the spacer is most likely useless; ouch! I knew I would get picked on for that one However some cold air intakes have been shown to improve performance. The cheap ones on eBay are probably a waste of money but other higher end kits like K&N and Volant with heat shields (etc) are good products otherwise they would be required to state “for entertainment purposes only” on the box.

This truck has cost me thousands of dollars to maintain and fix/replace parts that are designed to break so new ones need to be purchased (entrapment?) so I have lost a lot of faith in GM and federal guidelines too. If I have to alter the workings of my truck in order to save myself from going bankrupt and going nuts at the same time then so be it. I don’t believe any additional emissions caused by my Jimmy are going to bring about the apocalypse. If I win the lottery tomorrow then I will gladly convert my GMC to burn cooking oil and take a trip across Canada smoking water-vapour cigarettes with Captain Planet ("he's our hero!" does anyone remember him?) One interesting thing in my mind is why hasn’t the government outlawed old K5’s or Scouts? They surely spit out more emissions than my poor little 2000 vortec? Could it be because those trucks will require new parts at one point in the not too distant future and feed the automotive market yet again? No that's not it, most likely the emissions-act was passed after these vehicles were produced therefore its okay to turn a blind eye, sorry mother earth! I wonder what the emissions are like at the mud bogs with all those modified truck’s with 49” tires that spit out black smoke and block out the sun?

 

Do a little search on you tube "cash for clunkers". You will see some beautiful car's going to a sad and untimely end. Politics aside evap canisters can be re-loaded with activated charcoal from the pet store.

It just takes some time and ingenuity.

Depends how bad you need to get away from the wife.

I rebuild everything, only so much Bravo a man can handle.

 

The throttle body spacer is designed to "swirl" the inlet air so fuel mixes more completely with it. There are only a couple of problems with that theory: After the air passes through the spacer, it enters the plenum. Any "swirl" that was created is lost in the plenum. The second problem is that the fuel is added at the intake port, downstream of the plenum, and the spacer. As the air & fuel mixture is drawn into the cylinder on the intake stroke, and then compressed, the mixture is "swirled" due to the "Vortec" design of the combustion chamber, (hence the name Vortec V6). Engines that are carbureted or have throttle body injection, might experience a very slight difference in performance using the spacer. On a port fuel injected engine like yours, it does nothing.

Keep in mind that fuel must be atomized and vaporized before it can be burned efficiently. After the air passes through the cold air intake, it's heated in the plenum, (before the fuel is added to it). As the air is being drawn into the cylinder, the fuel injector opens; atomization & vaporization occur instantly. Cold air intake systems might sound nice and look pretty, but that's as far as it goes

EDIT: Using those two mechanics, I can see how you spent thousands on repairs & maintenance

 

Hi i'm Chris and i have questions. i'm new here so i apologize if i overlooked the answer somewhere but here's my issue. (i'm also handy but i like to know what i'm doing before i do it with as much info as possible)

04 blazer 2 door 2wd code popped up P0455. just curious to what i can check out before i just start replacing everything at random as it can be pricey. i want to believe it is the charcoal canister but idk how to tell if that's the problem either. Any help is appreciated greatly!

 

P0455 is defined as a large leak (>.030") in the EVAP system. Locating leaks in the EVAP system can be a time consuming process. Could be any one, or more, of the following: purge solenoid on the engine, vent solenoid on the crossmember above rear axle, purge canister, fuel tank, fuel pump O ring, fuel tank pressure sensor, fuel filler neck, fuel cap, or any of the associated lines and hoses. Start with a good visual inspection. A smoke machine is the tool of choice, and a hand vacuum pump can be an invaluable tool for locating leaks. Best to check each individual component, one at a time. Apply vacuum and watch for vacuum to hold, or deteriorate. The most common problems are: fuel filler neck rusted out, vent and or purge solenoid stuck or leaking internally, fuel filler cap not sealing properly against filler neck. Here is the GM diagnostic flow chart: https://blazerforum.com/forum/diagno...0-370-a-53332/