Fuel Leak - Rear of Tank on Suburban

[coxpn2]

I'm hoping there is an obvious solution to this problem, which doesn't involve me dropping the tank AGAIN. But probably not, haha.

I recently replaced the sending unit with a spectra - I cut the threaded fittings off and hose clamped rubber lines for supply/return. After which I filled the tank and drove it for around 400 miles.

This morning I fueled up again, at my normal station, and let the pump shut off where it wanted to. (Didn't top off or anything like that, just let it click off). If I looked down the filler tube I could see foam so figured no top-off was required.

I drove about 5 miles home and parked on a level surface. When I went out a couple hours later I could see fuel dripping right in front of the trailer hitch/bumper. If I look up in there it appears to be dripping off the back edge of the tank. It's maybe 1 drip every 10 seconds or so... maybe a cup every couple hours?

My question is - where is this coming from? I have a couple theories, but I'm looking for ideas... If it dripped right after I did the sending unit it would make sense I didn't seal something right or tighten a clamp, but this is the 2nd time I filled up. Any thoughts?

 

[Burning oil]

Put alittle pressure in the tank and see if it still leaks or get worse, maybe you'll hear air escaping? If it get worsr the leak is probably in the lines or FSU.
Did you take the sock of the Spectra FSU, if not I'd suggest droping the tank and removing it anyway. Gives you a good excuse to drop the tank anyway. You'll need to add a pre LP filter if sock is removed.
The Spectra socks are for gasoline and present problems alot when used on diesels.

 

[Will L.]

Sorry, its gotta come down. Run the tank near empty, then drop it. If you have a pressure regulator you can steal off a paint gun or something, hook it up in your airline from a shop compressor. With the tank out of the rig, fold the fill hose over on itself as a seal. same with overflow hose and fuel output that goes to the lift pump. 2-3psi air into the fuel return line your leaks will show up (a donut says o-ring at the lock ring). Mix a little dish soap with water in a spray bottle and squirt on the areas in question- bubbles are bad but helpful lil things.

Do be careful of no open flames around when doing this. Gas is obviously making a bomb, but diesel can go boom also.

 

[coxpn2]

Put alittle pressure in the tank and see if it still leaks or get worse, maybe you'll hear air escaping? If it get worsr the leak is probably in the lines or FSU.
Did you take the sock of the Spectra FSU, if not I'd suggest droping the tank and removing it anyway. Gives you a good excuse to drop the tank anyway. You'll need to add a pre LP filter if sock is removed.
The Spectra socks are for gasoline and present problems alot when used on diesels.

Sock is gone, and I've got your pre-lift pump filter in there too! (I was hoping to not have to drop the tank again for the sock, or anything for that matter!!)

Sorry, its gotta come down. Run the tank near empty, then drop it. If you have a pressure regulator you can steal off a paint gun or something, hook it up in your airline from a shop compressor. With the tank out of the rig, fold the fill hose over on itself as a seal. same with overflow hose and fuel output that goes to the lift pump. 2-3psi air into the fuel return line your leaks will show up (a donut says o-ring at the lock ring). Mix a little dish soap with water in a spray bottle and squirt on the areas in question- bubbles are bad but helpful lil things.

Do be careful of no open flames around when doing this. Gas is obviously making a bomb, but diesel can go boom also.

I thought about it being the seal around the tank, but I caked it pretty heavy in grease before I put it back in. (By caked I mean I took a tube of grease and plopped it on and smoothed it out... filled all of the holes and such) I suppose either way it needs to come down... Bummer, I was hoping someone had some miraculous idea that wouldn't involve that.

Thanks for the help guys!

 

[Burning oil]

Seems you'll need to drop it, but maybe you can see something with an inspection mirror and a flashlight before?

 

[coxpn2]

I'm thinking I'll jack it up good and try and drop it only a little bit to see up top. Hopefully I'll be able to see up there and maybe get lucky tightening a hose clamp or something. It takes us around 4 weeks to go through the entire tank... probably be winter by then.

Although more likely I'll drop the whole tank off the jack and flood my driveway with 40 gallons of fuel...

 

[ak diesel driver]

siphon hose can be your friend here

 

[coxpn2]

Siphon has worked great on the last (2) times I've done it... but I never have anywhere to put 40 gallons of fuel! Last time I used garbage cans... worked ok, but still a pain. I've actually found siphoning, as old-school as I used to think, works a lot better than screwing with rigged up lift pumps and stuff like that.

But anyway: my buddy and I dropped the full tank tonight. Wasn't too bad, just used (3) jacks and did it slow. Found a small pinhole leak in the rear of the tank where they put the padding to keep it from hitting on the frame. The rest of the tank looks fine, but is rusty in the "ribs" where the padding is, so I'll probably just get another tank.

On that note, I found one on craigslist for a gasser. I haven't been able to find definitive that a gasser tank will fit on mine. Anyone know for a fact? He wants 80 bucks, so not sure if it's that great of a deal considering RockAuto has them for $150, but worth considering because I could get the truck back on the road quicker.

I figured I could fix the leak, but another one will probably pop up in the middle of winter. And it'll be a lot easier putting a new (empty!) tank in and just siphoning it back in...

 

[jrsavoie]

I have one I would sell you for $300 a ton. The problem would be getting it to you.

 

[Burning oil]

Gasser tank is the same on all the ones Ive seen. Sending unit is different though so need to swap it out.

 

[jrsavoie]

When we swapped my buddy's gas tank we could not use the diesel tank. I do not know if it will work easily the other waY around. At about 10 cents a lb. my would be about $5

But I think shipping would be a killer.

 

[coxpn2]

When we swapped my buddy's gas tank we could not use the diesel tank. I do not know if it will work easily the other waY around. At about 10 cents a lb. my would be about $5

But I think shipping would be a killer.

Not bad if you were down the street...

I think I'm going to use a repair substance (JB Weld, fuel tank repair epoxy) or something like that and fix the hole. Then use some rust-stop to try and minimize the rusting at the back of the tank.

It's a little ghetto, but if it holds, great. If it doesn't, then I'll get a new tank and put it in at some other point.

Hindsight being 20-20, if I would have known it was a hole in the tank I never would have dropped it...just let the level get below the hole and then put a new tank in at my leisure.

At least I didn't screw anything up when I put the new sending unit in! I always like when the problem is something that I didn't do wrong... (Although its rare).

 

[Will L.]

I know what ya mean about the "I didn't do it wrong" part. It hurts my feelings too much when I do goof it up.

If it's a wear hole as in something rubbed through it, once jbwelded and the cause is corrected, you should be fine.

If its rust, then get to looking for one in your area or plan a weekend road trip to visit Illinois, and get your $5 deal.
I try to pick up deals as a short side trip when doing the road trips with the family. Of coarse the last trip to big bear was supposed to net me 6 spare used hmmwv tires on my way back but somehow it got away from me.

 

[jrsavoie]

If there is anybody driving by and heading his way we could get the tank to him.

I also have the cross members. Check your cross members while the tank is down. I have had to replace 1 cross members so far. They were rusted through. One of them looked fine til I hit it with a hammer for some reason. Then it just fell to pieces. I think I was just trying to knock some stuff off of it before I wire brushed and coated it with rust converter

 

[coxpn2]

I believe I can get a tank for around $200 shipped to my door, so I'll probably go that route. I don't see anyone offering plastic tanks, if anyone knows of a source let me know. I've seen some reports of the Spectra Premium flaking off the inside surface, so I'll probably go with the Dorman...

I'm assuming the cross members are fine - it was a southern truck, and still has all of the paint on the underside body panels and some on the frame too. Hopefully that won't be an issue, but next time it's down I could check them out just to be sure.

Took me about an hour last night to putty the hole and get the tank back up there. Not bad considering it was full and it was dark! Wife is going to drive it today, so we'll see if it starts leaking again. If it does, I'll let the level get below the hole and just not fill it until I get the new tank.

Thanks again guys!

 

[hookedup50]

I've looked for poly tanks for both the burb and pickups to no avail. The burb tank fits nicely as a dual tank for my jeep grand wagoneer as the single tank on it only gets me a 200 mile range.

 

[Big T]

Siphon has worked great on the last (2) times I've done it... but I never have anywhere to put 40 gallons of fuel! Last time I used garbage cans... worked ok, but still a pain. I've actually found siphoning, as old-school as I used to think, works a lot better than screwing with rigged up lift pumps and stuff like that.

But anyway: my buddy and I dropped the full tank tonight. Wasn't too bad, just used (3) jacks and did it slow. Found a small pinhole leak in the rear of the tank where they put the padding to keep it from hitting on the frame. The rest of the tank looks fine, but is rusty in the "ribs" where the padding is, so I'll probably just get another tank.

On that note, I found one on craigslist for a gasser. I haven't been able to find definitive that a gasser tank will fit on mine. Anyone know for a fact? He wants 80 bucks, so not sure if it's that great of a deal considering RockAuto has them for $150, but worth considering because I could get the truck back on the road quicker.

I figured I could fix the leak, but another one will probably pop up in the middle of winter. And it'll be a lot easier putting a new (empty!) tank in and just siphoning it back in...

I have a tank in a Suburban. Make me an offer. Shipping is on you.

 

[coxpn2]

I have a tank in a Suburban. Make me an offer. Shipping is on you.

I have to believe it's going to be more to buy and ship a used one than a new one... thanks for the offer though!
Honestly, I have no idea how they can ship a new one to my door for $ 170... that's pretty darn cheap.

 

[jrsavoie]

I have to believe it's going to be more to buy and ship a used one than a new one... thanks for the offer though!
Honestly, I have no idea how they can ship a new one to my door for $ 170... that's pretty darn cheap.

They must get one heck of a deal on shipping. You can't beat that.

 

[JayTheCPA]

I've seen some reports of the Spectra Premium flaking off the inside surface. . .

Recall seeing them as well when I searched for a replacement tank last summer. Went with the Spectra anyway as the reports seemed like they were from a narrow time period a few years ago.