FYI, -13.94 inches of H20 is 1.03" of vacuum (Hg). Not sure if that was your reading at some point or a specification for a test. Just thought I would convert it for you so it makes more automotive sense.

 

Thanks Les! The Tech2 gave the -13.94 inches of H20 as the reading for the fuel pressure. Honestly without me starting to do more research, all of it is getting too advanced for me! Bottom line sensor needs to be replaced New pump with sensor is here - yippee!!

 

Do you mean fuel tank pressure? -13.94 inches of H20 is not a lot, and it is vacuum. But if the pressure sensor fixes the problem, I'm sure you won't care.

Let me ask you if this vehicle requires a slow fill at the gas pump to keep the handle from clicking off a lot? If so, IMHO it's most likely the Evap Cannister causing the P0446 (since you already replaced the purge valve). Such was the case on my 2004 Avalanche when I first bought it - it was puking an occasional P0446 (was told by the dealer, who used it to pull his boat around and had already replaced the purge valve attempting to fix - so that was cool of him).

FYI if you have Car Gauge Pro (can't remember if you do or not), it can monitor fuel tank pressure and toggle the evap solenoid on/off. Yes it has some functional bidirectional controls. Won't run a specific test though. Recently found out Car Gauge Pro will toggle the Secondary AIR pump on/off as well.

Good luck!

 

The PO446 means that the air flow from the canister into the gas tank didn't happen (or didn't happen fast enough) when the purge valve was opened during the normal everyday vehicle evap testing. If you suspect the pressure sensor is stuck at reading too high, just take the gas cap off and read what the PCM sees from the pressure sensor.

 

Yes, I did mean fuel TANK pressure! I don't have any issues with filling the fuel tank. Both of the running Blazers take about the same time to fill from 1/4 tank and do so without stopping. I do not have Car Gauge Pro, at least not yet...

I'll take the gas cap off and see what the PCM says...

Thank you Sir!

Is it Spring in Indiana? Supposed to snow in Iowa AGAIN this weekend....

 

With the gas cap removed, fuel TANK pressure readings are still the same...

 

Lots of rain here in Indiana today but supposed to be cooler tomorrow. If the pressure sensor reads vacuum with gas cap off then I think you have found the problem. Best wishes!

 

Okay...

so the fuel tank is down...
old pump assembly is out...
new Delphi pump assembly, retaining ring, fuel filter, tank straps and metal fuel lines have arrived...

I think removing the rusted fuel lines was worse than dropping the tank. Dropping it wasn’t so bad at all!

Here is were things get interesting though. The new pump has a rectangular four wire plug vs the old square four wire plug. No big deal, it came with crimp connectors and I have a crimping tool. BUT, I’m not crawling back under there to find a future loose crimp connection so solder and heat shrink it is. When I pulled the old electrical tape and corrugated tubing off, I find the black wire that goes to the fuel tank pressure sensor is broken about two inches back from the connector! How in the heck does that happen?? You can tell it had been broken for a while too by looking at the copper wire...

The wiring is all good to go now. I can just imaging my confusion had I not found and repaired that prior to reinstalling the tank.

Well, off to install the fuel lines. I hope the new ones go in easier than the old came out!

 

Good find..Whether it be luck/skill or whatever...this could have turned into much more difficult situation..either way..Good find! Saved yourself hours of frustration. Jerry

 

It was pure luck for sure!

Alright, the rear fuel lines are all back in. Thank you to Les for mentioning lines 2 go in a separate post. I ordered their kit and everything fit great. The kit is only 3 lines, so I had to bend the front tank vapor line myself... no biggie.

Another question though... how much pressure is the return line from the engine under? The quick connector on the fuel return line coming from the engine side broke when attempting to remove the steel line. I have an eyxtra set of front fuel lines, but really don’t want to replace the entire line if I do not have to. I also do not to risk something leaking either though. I have a dorman fuel line repair kit. Unfortunately, there is not enough length in the current nylon line return line from the engine to simply install a new quick fitting. Here are the options I see:

1: nylon to nylon compression fitting
2: nylon to nylon b arbed fitting
3: nylon to steel compression fitting
4: run a different complete line

I don’t think my kit has a nylon barb to metal compression, but I would think that option probably exists too...

Thoughts? Thank you!