Small/slow gas leak developing

[mntb]

After my trailblazer ext decided it was time to retire, I am now the owner of a 2003 GMC Envoy sle 4.2l.
After owning it for three days the water pump broke. The housing actually broke, there is a window in it. Fixed that.

But now it seems as though a small/slow gas leak has developed. It's small, a few drips after Parking here or there. However there is a pretty strong smell of gas. It's coming from the top of the tank from what I can tell. I haven't had time to get it up on ramps to investigate further. I'm not even sure I will be able to seem the leak even if it up on ramps.
I believe at one point there was a recall for a gas leak, correct me if I'm wrong. I know
My tb ext had a larger Gas leak but I don't remember the sort e of it though.

Can someone tell me some likely spots it could be leaking from? And what would most likely need to be replaced (pump, lines, the tank, the whole assembly, etc.)?

It sucks that all of this has gone on right now, very bad timing. Don't get me wrong, I actually really like the envoy. The past 3 cars we have bought have need some sort of repair of $1000 or more in the first 6 months of owning them. But after that they were all very dependable.

Thanks in advance.

 

[Mounce]

Check around the filler neck on the tank. That's where the ext's often crack and that's what the current recall is for. Not sure if it includes the short wheel base models though.

Also check the filler tube, have heard of a few cases where the metal portion rusts through.

Either way I think it might be the tank itself as it's leaking daily and not just when fueling. Just follow the wet smear and see where it's coming from. If it's on top of the tank it'll have a trail going down the side to where it's dripping off.

 

[Mooseman]

It could also be from one of the fuel lines. I had the main one rust through on top of the tank and had to replace the whole fuel pump unit. Could also be the return line which is lower pressure. If you're not getting a code for an evap leak (i.e. the same as leaving the cap off), I would suspect something like that.

 

[mntb]

How difficult would it be to change the pump and/or tank? when comparing this job to something easy (brakes, wheel hubs, etc) or something like changing the spark plugs on the 5.3l?
I have ramps that are a little taller than most (they look to be home made, metal, and heavy), Jack stands, floor jack.

It doesn't SOUND too difficult.

If the bolts for either the straps or the cross bar break (which I suspect at least one will) are they replaceable?

I see rockauto has cheaper fuel pumps for around $100 or less. Anyone use the "economical" fuel pumps from rockauto?

Thanks for the replies.

 

[gmac310]

How difficult would it be to change the pump and/or tank? when comparing this job to something easy (brakes, wheel hubs, etc) or something like changing the spark plugs on the 5.3l?
I have ramps that are a little taller than most (they look to be home made, metal, and heavy), Jack stands, floor jack.

It doesn't SOUND too difficult.

If the bolts for either the straps or the cross bar break (which I suspect at least one will) are they replaceable?

I see rockauto has cheaper fuel pumps for around $100 or less. Anyone use the "economical" fuel pumps from rockauto?

Thanks for the replies.

The hardet part is trying to unhook the fuel lines while the tank is hanging partway down because you can't get your hand in there while the tank is still bolted up and the lines aren't long enough to allow the tank to drop all the way to the ground.

 

[mrrsm]

One of our Legendary Members… @MAY03LT has done Two Videos that nicely cover the Fuel Filter and Fuel Pump R&R Repairs. If the the Fuel Pump Locking Rind has rusted through and lost its grip… Use a Brass Punch and Plastic Mallet to knock it loose if necessary as “No Sparking Tools” and having a Fire Extinguisher nearby are the order of the day. It would be wise to to check to see if the Fuel Filter and lines are the culprit first as the Fuel Tank Drop and Repair is more involved … by Orders of Magnitude.

AC-Delco OEM Replacement Locking Ring:

https://www.carid.com/acdelco/gm-original-equipment-fuel-tank-sending-unit-lock-ring-mpn-tr14.html

His videos are just about the best suggestions for this How-To that can be found… and if you watch the very ending of the Fuel Pump replacement FIRST… his afterthoughts on which pump(s) to purchase and avoid if needed are excellent. Replacement Steel Pump Lock Rings are not very expensive and unless the Big Tank Seal is damaged on removal… it can be re-used.

Having a Floor Jack handy will be very useful here as well. Please remember… Its not the Gasoline that burns easily… its the fumes… so no Kurious Kids running about and NO Nosey Neighbors with lit cigarettes dangling down from their mouths ogling your work up close will ease your mind here as well:

Fuel Filter R&R:

Fuel Pump R&R:

 

[Mounce]

Most do not recommend the cheap fuel pumps at any cost. Cheap pumps will have you replacing it again in a year when it goes out. Most recommend Delphi for fuel pumps.

 

[Mooseman]

Yep. Delphi, ACDelco are known as the "good" ones. If really pressed for cash, you could go with any of the majors like Bosch, Standard, Carter. Absolutely stay away from the white box and unknown brands as they are likely CCC (Cheap Chinese Crud). I have had personal experience with these and they do not last.

 

[mntb]

Good info guys. Thank you.

Any ideas if the bolts on the cross bar or straps are replaceable?

This is not a job I want to do right now. But I'm sure it will go from a small leak to a guiser soon enough.
When I had the ext's tank fixed the bill was over $1000. I definitely don't have that kind of cash laying around. So if this is possible for me to do in my driveway, then so be it.

Thanks again for the replies

 

[Mooseman]

The if the crossbar bolts break in the frame, they are not replaceable as they are welded in the frame. The strap bolts are however the "J" type and are replaceable if they break.

 

[mrrsm]

If the Gas Tank Straps have been corroded and eaten away by Road Salt… CARid carries a paired replacement set for under $40.00. Most of the GM Under Body Fasteners are usually 9.8 Metric Quality and are made of Parkerized or Zinc Plated Steel that is “Harder than Chinese Math”. Even if severely rusty… they should clean up pretty good with some Kroil Rust Spray and a short spin under the kind attentions of a Wire Wheel 3/8” hand Drill Accessory after being clamped in a vise on the Bolt Heads:

https://www.carid.com/spectra-premi...-mpn-st243.html?singleid=22801864&url=2681427

In a WCS (Worst Case Scenario) something like this Dorman HELP! Replacement Fastener Kit might work. The one depicted is NOT specifically made for your 2003 Trailblazer… but you’ll get the idea:

https://www.amazon.com/dp/B001M6VAHS/?tag=gmtnation-20

 

[DocBrown]

There were actually 2 extended warranties for this issue. Both involve replacing the fuel pump. I had it happen on my '03 TB but I was out of the extended warranty period. As I recall the top of the pump rusts and damages the seal.Hence the leaking and gas smell. I can't remember what the other issue was but both involved smelling gas.

Unfortunately it was a 10 year warranty so even if your TB has under 120k miles the warranty has expired.