My wife and son took my son's 1996 Blazer out of town this afternoon and called to let me know that gas is leaking from underneath the drivers seat. Three or four months ago, the fuel pump and fuel filter were replaced along with new intake manifold gaskets. Ever since then, there's been a slight odor of gasoline from around the drivers door but no visible leak.

After playing 20 questions with my wife and son, I was able to get the following information from them:

1. My wife filled the gas tank but didn't top it off. I believe it's the first time, since the repairs I mention above, the tank has been that full.
2. They confirmed that the fuel filter isn't leaking.
3. They said that there's a steady drip coming from a black "pan type thing" located on the frame between the drivers seat and rear passenger door.
4. The truck still starts and runs very well.

My questions:

1. What is that black "pan type thing" that has gas dripping from it?
2. Is it possible that the gas is leaking from somewhere toward the rear and running down the frame and off of the black "pan type thing" ?
3. I'm sure this has something to do with either how the tank was filled or the amount of gas in the tank. Any suggestions on what I can start looking for when they return?

Thanks

 

It could be leaking from top of tank. vent hoses, filler hose, etc. About all you can do is crawl under it & see were it starts from. With gas you should be able to see, even if it isn't leaking. The gas should leave a trail of where it is coming from. As for the black pan type thing could that be the skid plate?

 

The black plastic is most likely the tank skid plate, mine is leaking from the drivers side of the tank above the half full point. Mine smelled like gas for about the last year with no leaks then I filled it up last and drip drip drip until it got down to just above half a tank.

 

Is it a constant leak even after parked overnight, or does it only leak with the engine running?

I have a 97 blazer 4-door. I went through this in April 2010:

If it's constant, drive it to 1/4 tank or disconnect feed line at fuel filter and run the pump for a while (put into a gas can, obviously). It's easiest to jumper the relay socket in the glovebox or the control wire that goes to the relay from the ECM (not sure which computer the 96 has, might be different than mine). On mine, it's pin1 on C4 of the VCM (dark green/white-stripe upper drivers side VCM plug). See http://www.justanswer.com/questions/1y110-i-have-a-1997-s10-blazer-with-a-4-3-with-csefi-the-in-tank

I had three leaks pop up on me this year, each one caused by the previous! First leak I encountered was a rusted main fuel line under the rear passenger door-- just started leaking one morning after I started the engine. It was a relatively slow leak (1 drip per second or less, wet frame rail)

A few days after redoing the lines, it started leaking again. I thought I botched the new lines, but there was a small set of rust pinholes just above half a tank that had cracked open when I jacked the tank back up and the rust layer flaked off.

If you have to do your steal lines, I'd recommend putting a new tank on at the same time if it has any signs of rust. Use the original blue fuel tank O-Ring. The O-ring that came with my $110 carquest tank didn't seal correctly and it leaked out the seal when I filled up! (the THIRD leak..)

My front tank strap retainer bolt sheared apart the first time I dropped the tank because the nut was rusted on. If this happens, you can maybe weld it using a new bolt, or go to a GM dealership and have them get a new bolt.

The lines are a also a GM-specific part. I decided they were too expensive for my old girl (over $300 for the full set of evap/return/feed), so I bought some 3/8, 5/16, and 1/4" steel brake/fuel line and cut to length with a tubing cutter. It bends no problem. I re-used the ends of my fuel lines (still good, not rusted) and connected the GM quick-connect ends to the new steel lines with high-pressure fuel injector hose (expensive stuff!) and fuel line hose clamps (all of this came from Advance Auto).

If you only have to do the tank, carefully inspect your lines and consider replacing them as preventative maintenance. My evap lines were so brittle they broke apart when I touched them.