H3 Fuel Tank Pressure Sensor troubleshoot

[denlion]

Hi fellows,

I have just replaced Fuel Pump and line on my 2007 H3 and got P0452 after first run. Tried to clear it (thought PCM detected low pressure at the first start) but no luck - it is coming back.
I have found this video which explains it quite clear: https://www.youtube.com/watch?v=CkgrMasd57s

I guess the most probable cause are:

#1 - open wire (5V ref)
#2 - low pressure in the tank itself
#3 - bad pressure sensor (almost impossible, it came new with fuel pump assembly)

To eliminate #1 I need to probe sensor connector and I have a question what design my H3 PCM has - with resistor in it or without? Does anyone know?

Also, I wonder if someone knows could it be #2 if I done poor job in assembling the fuel pump? How would I diagnose that? I guess with bad installation I would also get fuel leak and smell, right? I am guessing if there is no leak/smell then #2 must not be my issue?

Thanks for helping.

 

[4speedfunk]

Probably a leak somewhere. This system is very sensitive and if it is not sealed up...it will throw codes. Bad gas cap gaskets are a common source for evap codes, and that’s usually what I start with. But since you recently swapped some other fuel related items, it makes troubleshooting more complicated. I would backtrack and make sure the fuel line connections are sealed up.

 

[denlion]

Probably a leak somewhere. This system is very sensitive and if it is not sealed up...it will throw codes. Bad gas cap gaskets are a common source for evap codes, and that’s usually what I start with. But since you recently swapped some other fuel related items, it makes troubleshooting more complicated. I would backtrack and make sure the fuel line connections are sealed up.

Thanks for the answer, but I assume if there was a leak somewhere I would smell gasoline. That is what the reason I have started all this job - get rid of gasoline smell which was actually a leak from rusted fuel line (see pics). Anyway, thank you for your reply. Not sure how, but will have to find what is the cause.

 

[Chimpy]

:holymolyI am now officially afraid to look at mine.

 

[4speedfunk]

Wow. Based on appearances only...that’s total junk! How did that get so rusty? I assume you replaced it?
It’s very possible the large ring on top of the tank is pitted and not properly sealing to the o-ring on the pump housing. I just went thru this same problem on my old Burb and the only solution was to replace the tank itself. I also had to buy the special tool to release the fuel line quick connect fittings (thanks GM).

 

[denlion]

Wow. Based on appearances only...that’s total junk! How did that get so rusty? I assume you replaced it?
It’s very possible the large ring on top of the tank is pitted and not properly sealing to the o-ring on the pump housing. I just went thru this same problem on my old Burb and the only solution was to replace the tank itself. I also had to buy the special tool to release the fuel line quick connect fittings (thanks GM).

Yes, I did replace it. And haven't noticed anything bad around that O-ring sealing. Looked good for me:



And I guess if there was an issue with that O-ring, then I would smell gasoline, right?

Also, could you please share what tool you had to buy? Thanks!

 

[4speedfunk]

Unless you are part bloodhound, I would not rely on any sort smell test to determine a fuel leak. The leak we’re talking about is so small it’s unlikely you would ever smell it. You might try somehow pressurizing the system and listen for hissing. Perhaps you could sacrifice a $10 AutoZone gas cap and drill & tap it for an air hose fitting?
The tool I used on my 99 Burb is this one...

It’s a complete POS but it was only $7 compared to $35 for the real (plier-looking) tool. Normally I just break off the plastic fuel pump fitting since I have a new pump in the box ready to be installed. But since you will be re-using your brand new pump, you’ll need to remove the hose carefully. You can get replacement quick connect bushings at most auto parts stores, and I would definitely do so. It’s too much work to take a chance on reusing a $1 plastic fitting.

Another example of GM engineering’s marijuana use. What the hell were they thinking? A hose clamp worked great for the first 75 years!