Fuel leak from the top of the tank.

bore_pig

Original poster
Member
Nov 25, 2011
113
Leaks like a bastard when the engine is running, with only 3/4 tank full. Could someone explain to me why this leak occurs? I haven't dropped my tank yet, but understand the leak to be from corrosion where the fuel pump locks into the tank.(The 3 tabs.) Why is there pressure there? I always thought that seal was solely to prevent gas from leaking out when the tank was full. Any redneck repairs to be recommended?
 

c good

Member
Dec 8, 2011
547
This is a fairly well known problem with this vehicle, especially when it's been driven in the salt belt. Debris(corrosive) collects on the top of the tank, but down in the access where the fuel pump and gas gauge sending unit cap sits. This corrosive debris works it's way through the plumbing coming out of the top of the tank. No Red Neck fix that I'm aware of. This gas is coming out of the tubing at high pressure. You need to get a new fuel pump/sending unit. I believe it was covered at one time by a Technical Service Bulletin, but I believe that's long gone time wise. HTH c good
 

bore_pig

Original poster
Member
Nov 25, 2011
113
Okay, that makes more sense. So the leak is where the high pressure tube comes out of the fuel pump then. Everything I read described the problem as being at the seal where the pump locks into the tank.

I would assume that this pump assembly is like any of the K1500 or suburban pumps I have done in the past, is that correct?
 

c good

Member
Dec 8, 2011
547
It's not the seal as you have noted. It is the whole top part of the fuel pump/fuel level sending unit that corrodes and leaks. I should be no different than a K1500 or Suburban (but I've never changed one from a K1500 or Surburban)so I can't say for sure. But you will need the a new pump/sending unit. HTH c good
 

Matt

Member
Dec 2, 2011
4,033
You may be lucky. Here is the letter I got about the problem. Might be worth giving them a call and finding out if your truck is covered.

ChevyPetrolTank.jpg
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ChevyPetrolTank2.jpg
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bore_pig

Original poster
Member
Nov 25, 2011
113
I called the local dealer on Tuesday, and I'm outside the 10 year/120000mi parameters. Don't know if they would've done it anyways, that guy was a dick. It's not all bad though, I need it done fast. No third vehicle right now cause my old truck needs a fuel pump too. I was able to drive my TB all week but will be doing the fuel pump this weekend. Can you believe our joke of a dealership didn't even have a new fuel pump on hand for my TB?
 

bore_pig

Original poster
Member
Nov 25, 2011
113

bore_pig

Original poster
Member
Nov 25, 2011
113
Got everything fixed up last Sun. Thanks again for the help guys. This was the easiest fuel pump I've ever done. Same thing as changing the fuel pump on K1500's/Suburban's I've done before except the fuel line connectors were easier to release. Having the 3" body lift helped too by allowing me to disconnect the wiring harness from the top of the fuel pump before dropping the tank. :thumbsup:
 

gkrenzer

Member
Apr 7, 2012
20
Matt said:
You may be lucky. Here is the letter I got about the problem. Might be worth giving them a call and finding out if your truck is covered.

Got an 03 TB EXT and just noticed the fuel smell. Can't find any leaks on the line. Has to be coming from the top of the tank. Might be the same problem described here. Do you know if the problem is covered for other model years?
 

Wooluf1952

Member
Nov 20, 2011
2,663
Milwaukee, Wisconsin
gkrenzer said:
Matt said:
You may be lucky. Here is the letter I got about the problem. Might be worth giving them a call and finding out if your truck is covered.

Got an 03 TB EXT and just noticed the fuel smell. Can't find any leaks on the line. Has to be coming from the top of the tank. Might be the same problem described here. Do you know if the problem is covered for other model years?

I got the letter covering my 2003 Envoy. Your truck should be covered if it meets the years/mileage maximums and state.
 

Matt

Member
Dec 2, 2011
4,033
Wooluf1952 said:
gkrenzer said:
Your truck should be covered if it meets the years/mileage maximums and state.

:iagree:

I posted the same letter in your other thread.
 

TonyT

Member
May 6, 2012
108
bore_pig said:
I called the local dealer on Tuesday, and I'm outside the 10 year/120000mi parameters.
I've occasionally noticed a gasoline smell too but I thought it was just the fuel cap. I was getting a fuel code so I changed the cap but I'll have to pay more attention to the smell. I wonder if the same coverage applies here in Canada. I'm just under the 10 year with the 2003 and somewhat under the 120K miles. Hmm, maybe, maybe not. I'd better check on this ASAP.

Thanks for starting this thread. Something else to check on.

BTW how can you see the gasoline leak?
 

Mooseman

Moderator
Dec 4, 2011
25,661
Ottawa, ON
Had mine done last year and they covered it, same coverage as the US. But you might want to hurry as it is 10 years from date of manufacture, not model year. Look for gas streaks/stains on the rear of the tank at the fill inlet hose.
 

TonyT

Member
May 6, 2012
108
Mooseman said:
Look for gas streaks/stains on the rear of the tank at the fill inlet hose.
How do you see those? There's some kiinda rubber spill shield between the sheet metal filler hole and the actual gas tank cap.
 

tom1999d

Member
Apr 24, 2012
32
I just changed mine. Bosch pump was recommended $355. The leak was horrific, I could see the gas gauge fall like Keanu Reeves in 'Speed'.
 

TonyT

Member
May 6, 2012
108
TonyT said:
I've occasionally noticed a gasoline smell too but I thought it was just the fuel cap. I was getting a fuel code so I changed the cap but I'll have to pay more attention to the smell. I wonder if the same coverage applies here in Canada. I'm just under the 10 year with the 2003 and somewhat under the 120K miles. Hmm, maybe, maybe not. I'd better check on this ASAP.
Finally got to the local dealership to ask. That's never been done to my vehicle and I still qualify. If that isn't the problem they'll charge me a half hour diagnostic fee.

*** If it is the problem looks like I get a new fuel pump/gauge sending unit for free. :smile: *** No, I'm wrong. Turns out I get a new fuel tank.

But I feel bad for the mechanic. I just filled the tank a few days ago not even thinking about this.

They gotta order in the tank anyhow, if that is the problem, so I'll time an appt for when the tank is reasonably empty. Which could be a while.
 

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