Thanks for all of your input. My blazer is about to hit 120k miles while my friend with the same year Blazer replaced his at 80k, so I guess that's not too bad for a stock pump. I've had several older blazers and the pumps lasted past 160k with no problems.

Yeah, I wish I could just replace the pump instead of the whole unit. But I guess since I would have to go through the trouble of dropping the tank, I might as well replace the entire assembly. Just reduces the chance of something else in the old unit going bad and me having to drop the whole tank all over again. I just wish these pumps didn't cost so much!

 

Just for FYI, the Airtex pump I have replaced in GM's before the O.D. reads avg of first replacement 185k |second replacement (if they last that long) 356k. Hence why I dropped it into my Blazer to see if it holds true with a different vehical.

 

I was planning on replacing my Fuel Pump this weekend to fix my starting issue, when my SES light came on yesterday. It gave me a P0446 code, which I believe was saying that my Evap Canister vent was blocked. So reluctantly I replaced the Evap Canister Valve and the Evap Purge Solenoid (I used OEM parts from the dealership). Since I was having problems keeping pressure over a period of time, I was really hoping it was the Purge Solenoid that was the problem instead of the fuel pump - unfortunately it wasn't.

From what I understand, the computer measures pressure through a sequence of opening and closing of the canister valve and purge solenoid while applying a vacuum and observing pressure decay. My question is, what leads the computer to think that the canister vent is blocked when I am already having problems keeping pressure to begin with? Nowadays in the morning, I only read 50PSI after allowing the pump to prime twice! Lately I have to use starting fluid to get the truck running in the morning. Isn't it high pressure that triggers the P0446 code?

Am I misdiagnosing my starting issue? I was convinced that it was my fuel pump and now I am not so sure anymore. I'd appreciate any input you might have before I go and spend $300 on a fuel pump. Thanks in advance.

 

I've also ran the truck for a day (~15 miles) and the SES light has not truned off yet. Isn't it supposed to turn off after a few miles?

 

JustBlaze
Your starting issue has absolutely nothing to do with your P0446 code. You said you replaced the Evap Canister Valve and the Evap Purge Solenoid, How is your gas cap? Did you clear the code when you done with your repair? Also are your battery cables clean?Is your battery fully charged? 50psi is no good, You need at least 60psi at the schrader valve, with the key on, engine off.

 

Gas cap was replaced 2 months ago. Battery is 1 month old and has a higher CCA rating, the cables have new connectors. Brand new plugs, wires, cap and rotor. Alternator is 3 months old. I did not clear the code P0446 becuase I though it was supposed to clear itself after a few cycles.

I really think its the fuel pump, but I'm really tight on cash so I would hate to be wrong. If there was a leak, it can't be that big of a leak since there is no visible drips, and the truck runs fine after I start it with starting fluid. Even with a leak in the system, will the pump (a normally operating pump) be able to pressurize it to 60 psi momentairly?

When I first started having this problem about 2 months ago I measured 58 PSI after priming the pump and the truck will start fine after sitting for 4 hours and struggle at 5 - 6 hrs. Now I can't even start it on its own after 3.

 

UPDATE: Finally fixed my starting problem! Figured I would do a writeup for others looking to do this.

I decided to replaced the fuel pump assembly this weekend. I wanted to get an AC Delco or Delphi but non of the stores had them in stock (go figure). I eventually went with a Carter fuel pump with a lifetime warranty from NAPA. Removing those two nuts holding the straps were quite an adventure. The one towards to front had an uber long bolt so you can't use a deep socket. I tried using an open ended wrench and loads of penetraing oil, but the bolt just wouldn't budge. I ended up cutting off a little bit of the bolt so I could use a deep socket. The rear bolt was an even bigger pain in the __. That was quite a retarded design the way they used a thin metal clip instead of an actual nut to hold the bolt in place. I ended up having to cut off that bolt becuase the clip broke and the bolt kept on spinning in place. When I was lowering the tank, I totaly forgot about the nipple towards the front of the tank for the hose that connects to the EVAP purge solenoid and valve. Ended up snapping it. Why they used such a short conecting hose, I don't know. Had to glue and silicon it back together (that thing will never brake now!) and replaced the hose with a longer one.

Once I finally got the tank out, I flushed out all of the old gas and clean the inside of the tank (Thanks to Hanr3 for mentioning that). The guys at NAPA told me that one of the leading causes for failures and returns was that people would just drop the new pump in without flushing the tank. Apparently the coating inside the tank overtime comes off, disolves and ends up cloggin the screen of the pump. If you don't flush the tank, all that gunk just sits in the bottom just waiting to clog up your new pump. The other cause of failure they said was the connectors, so I replaced those also. While I was at it, I also ended up spraying a few coats of primer on the tank since it was getting quite rusty.

After I got it all back together and installed, I poured a gallon of gas in and tried to start it... crank crank crank... nothing. Hooked up a pressure gauge to the shrader valve, 0 PSI! At this point I was ready to kill someone. I lowered the truck so that it would sit level and tried again. Lo and behold, she started! The pump just probably wasnt sensing enough gas since it was jacked up at an angle. Overall the whole process took me about 10 hours (including waiting for the primer to dry).

Thanks to everyone for your help in (directly and indirectly) diagnosing and fixing my problem.

 

i haven't had to put a new fuel pump on my blazer but i did put a walbro 190 fuel pump in my honda crx. dropping the tank and cleaning it out suxed but thats a whole new story, install was easy and the benefits of the new pump were obvious. also the walbro brand is spoken highly of on other forums and the price is awesome compared to everything else i have come across. worth checking out at least, just my 2 cents