What can come loose in the tank?

fatweasel · **Posted:** Tue Aug 08, 2017 7:31 pm

So last week my fuel gauge was acting funny.

Reading empty with 1/2 tank and another time reading full with 1/2 tank.

Problem seemed to correct itself this week with no intervention. Filled up and gauge is reading properly based on miles driven.

When I pulled into the garage this evening, with about 1/2 tank, there was a "thud" coming from the tank. Sounds like the frequency is from fuel sloshing back-and-forth from the stop.

Are there baffles or other things in the tank that could have come loose.

I hate to drop the tank - it is a pain in the arse for sure. Mine requires the trailer hitch to come off...

GordnadoCRD · **Posted:** Tue Aug 08, 2017 9:59 pm

The fuel gauge thing sounds more like an electrical short, or bad connection/connector, or bad / loose ground.

The "thud" noise sounds like you should check your hitch mount / Tank skid mounts, and Tank Straps. Possibly a loose hitch if you have one in your receiver.

There really isn't anything inside the tank that could "thud", unless someone put big steel ball bearings or a piece of metal rod or something in your tank through the tank filler tube. No baffles for sure.

Another possibility would be if the tank vents plugged closed and it developed a vacuum, which self corrected as you entered your garage.

The most likely thing is a suspension component, such as the upper "boomerang" axle control mounts.

fatweasel · **Posted:** Wed Aug 09, 2017 11:34 am

Definitely coming from the fuel tank.

I suppose it could be part of the level/float assembly, a baffle (if there are any) or some other part - maybe from the vent or filler tube?

APC9199 · **Posted:** Wed Aug 09, 2017 2:54 pm

fatweasel wrote:

Definitely coming from the fuel tank.

I suppose it could be part of the level/float assembly, a baffle (if there are any) or some other part - maybe from the vent or filler tube?

How do you know?

GordnadoCRD · **Posted:** Wed Aug 09, 2017 3:25 pm

fatweasel wrote:

Definitely coming from the fuel tank.

I suppose it could be part of the level/float assembly, a baffle (if there are any) or some other part - maybe from the vent or filler tube?

Vents and filler tube are exterior of tank. No baffles inside.
The float is way to light to make any bonk noise. it's super light plastic. The float arm is like a bent coat hanger made of spring steel. Not heavy. Would make, at most, a tiny scratchy sound.

The only possible thing would be if the sending unit clamp ring came loose, and that bastage is NOT gonna come loose of it's own accord. Besides, if it did, you would get fuel flowing everywhere first time you tried filling it.

crdieseljeep · **Posted:** Tue Aug 15, 2017 12:44 am

I just got done dealing with this issue my fuel gauge is acting weird pop down the tank and pull out the sending unit, mine completely separated and was sloshing around the tank . I replaced with the Airtex. There are two metal sticks with springs that can separate. The two sticks rolled around the tank causing noise. It still worked it just was separated and slashing around. I also replace my Inlet with a braided fuel line. Check around the form for how to replace with an Airtex they have great write-ups. I also have a trailer hitch I did not have to remove it I removed the back bumper and was able to reach the bolts I am not sure how yours is set up a but with mine I did not have to drop at the hitch.

GordnadoCRD · **Posted:** Tue Aug 15, 2017 3:09 am

Well I"m glad you found it.
Thanks for letting us know what happened, because I've never heard of that failure before.
I wonder if the unit, once it was compressed, was able to twist when the locking ring twisted back together.
So the "thump" you heard must have been the pump/motor assembly hitting the front of the tank. It's the only thing heavy enough to make a noise like that.

Also you must definitely have a different setup than mine. I have a tank held on by just 2 straps.
Around the tank is a fairly heavy steel skid/tank protector, attached to the frame rails with 6 very large bolts.
The same 6 very large bolts also mount the hitch receiver to the frame.
All of that has to come out for me to even get to the tank.
How very large? Well the torque spec is about as much as an average guy can apply with a 20" 1/2" drive breaker bar.

WWDiesel · **Posted:** Tue Aug 15, 2017 7:42 am

crdieseljeep wrote:

I just got done dealing with this issue my fuel gauge is acting weird pop down the tank and pull out the sending unit, mine completely separated and was sloshing around the tank . I replaced with the Airtex. There are two metal sticks with springs that can separate. The two sticks rolled around the tank causing noise. It still worked it just was separated and slashing around. I also replace my Inlet with a braided fuel line. Check around the form for how to replace with an Airtex they have great write-ups. I also have a trailer hitch I did not have to remove it I removed the back bumper and was able to reach the bolts I am not sure how yours is set up a but with mine I did not have to drop at the hitch.

Very interesting! :shock:

Good to know for future reference....thanks for sharing!
As to hitch; when I dropped my fuel tank to install fuel pump back in 13, factory hitch was not an issue, only had to undo two straps and filler pipes.
Mine does NOT have a factory fuel tank skid plate though...

fatweasel · **Posted:** Sat Oct 21, 2017 1:39 pm

Dropped the tank this morning. Found the same problem as reported by crdieseljeep. The entire sending unit has separated. The base was only connected by the fuel supply/return tubing. There were two metal tubes and two springs rolling around in the tank.

Installed a Carter in-tank fuel pump. Not too bad of a job, about 4 hours.

Seems to be working well now.

WWDiesel · **Posted:** Sat Oct 21, 2017 2:49 pm

fatweasel wrote:

Dropped the tank this morning. Found the same problem as reported by crdieseljeep. The entire sending unit has separated. The base was only connected by the fuel supply/return tubing. There were two metal tubes and two springs rolling around in the tank.
Installed a Carter in-tank fuel pump. Not too bad of a job, about 4 hours.
Seems to be working well now.

A couple of questions for clarification!
Was this the OEM tank unit that came apart? (not a replacement unit)
Did you have to drop your hitch receiver to drop fuel tank as some were saying?
Knowing this may help some others in the future if they hear a noise coming from their fuel tank!

Just replaced the OEM fuel tank unit in my 96 Dodge gasser; gauge quit working a while back.
Good friend who is the Commercial Manager for the local Autozone informed me Carter and Delphi brand units were the only ones worth considering nowadays, everything else he said was junk and would not last...so I got a Carter unit! :shock:

fatweasel · **Posted:** Sun Oct 22, 2017 8:45 am

Sending unit was the original OEM. Symprtoms were audible "thud" from the tank that would be evident after parking, shuting down engine. The frequency of the thud was consistent with the fuel sloshing in the tank. Was more noticible when the level was low. Also had some erratic fuel level readings. Makes sense as I am sure the base of the unit flipped on its side from time to time.

I removed my trailer hitch to make the tank strap bolts more accessible. You might be able to reach the rear strap bolts with a toggle fitting, but the hitch meks things pretty tight.

I'll try and post a photo if I can figure it out.

WWDiesel · **Posted:** Sun Oct 22, 2017 11:43 am

fatweasel wrote:

Sending unit was the original OEM. Symprtoms were audible "thud" from the tank that would be evident after parking, shuting down engine. The frequency of the thud was consistent with the fuel sloshing in the tank. Was more noticible when the level was low. Also had some erratic fuel level readings. Makes sense as I am sure the base of the unit flipped on its side from time to time.
I removed my trailer hitch to make the tank strap bolts more accessible. You might be able to reach the rear strap bolts with a toggle fitting, but the hitch meks things pretty tight.
I'll try and post a photo if I can figure it out.

Thanks for the additional info! :wink:

Big Montana · **Posted:** Sun Oct 22, 2017 11:10 pm

Though I've not fixed my tank yet, I've had this same problem for at least 5 years. I have to use my trip odometer to track fuel usage. When I hit 400 miles, I stat looking for fuel.

I've had the sloshing clunking noise for so long I don't even notice it any more.

Farm Boy · **Joined:** Tue Jan 08, 2013 9:59 am **Posts:** 9

Hi, just wanted to add in case it's helpful, I had the same thing happen to mine. The fuel gauge was erratic and also it would run out of fuel before the fuel tank was actually empty. The two pipes and springs hold the fuel pickup at the bottom of the tank. I fixed the pipes and the problems where solved. Just another possible symptom to look for.

What can come loose in the tank?

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