Dropping fuel tank for inspection sending unit

[aantalis]

I need to drop the fuel tank to check the sending unit connections for proper ground. Anyone know if I will need to disconnect fuel lines or can I just remove the guard and drop the tank and leave all the lines connected for this inspection?

I suspect previous owner put in a poly tank and did not connect a ground wire as he told me the gauge never work since he put it in. I’ve tested to gauge with resistance diodes and send it seems to be working properly.

[tgreese]

Which vehicle is this? At some point, Jeep put an access hatch in the floor of wagons. Worth a look.

I've only dropped tanks on J-trucks, and there you need to disconnect the big hoses first. The small hoses and wires can be disconnected after you lower it some.

[devildog80]

My '84 Grand Wagoneer I recently dropped the tank for initial cleaning and inspection.

It was a poly tank OEM, had to pull the driveshaft off rear yoke for clearance (skid plate slips over bottom frame lip so need to slide tank towards center of truck to clear), and did have to disconnect all lines from the tank.

Glad I did as all the rubber lines were very far gone, and I was easily able to pull the sending unit out with the tank on the shop floor.

Found the sender was not working, so opened it up, then cleaned the coil and other internals of gasoline residue that had dried on everything. Works perfect now, and saved the cost of a replacement!
(carefully bend the metal tabs back and remove cover - clean/test - replace cover and carefully bend tabs back down) See my build thread - '84 Grand Wagoneer Revival

Hope this helps

[aantalis]

No floor access on this 79 Cherokee. Has anyone ever thought of drilling an access to the sender with a hole saw? I really dont want to pull the driveshaft.

I am hoping to be able to reach the sender and attach a ground wire to a tab without dropping the whole tank. PO said he put in a new poly tank and sending unit. I would presume the seller would have sent him a unit with a grounding tab. I stuck my fiberoptic up there and see only the sending wire.

[devildog80]

You may not need to pull the driveshaft on yours, as I only found I needed to on mine.

I have found others did not need to pull theirs, as they apparently had more room than I did, but it only takes a minute to yank the two straps off and move it.

Biggest part dropping my tank was the hoses connected do not allow the tank to drop all the way to the ground.

Cutting an access hole....yes, again many do that, just watch your wiring on the bottom side.

My '84 GW does have the two wire hot/ground.....just fwiw

[tgreese]

You could cut an access hole if you don't damage the tank below. I'd think it would be difficult to know where to put the hole if you didn't have the tank down. The tank design for '78-79 is quite different from '80-up.

I would encourage you to drop the tank. It's not hard if the tank is empty. Use a floor jack and a helper if you need to. The plastic tanks are supported by the skid plate, so when you take that loose, everything comes down. Once the tank is down you can measure for an access hole and be sure it's in the right place.

If you need a place to put the gas - https://www.amazon.com/VP-Racing5-Gallo ... 00AVQC01U/ 10' of cheap 3/8" fuel hose plus a MityVac makes draining the tank easy. The siphon hose is a good thing to carry, regardless.

[aantalis]

Thanks guys, I got under today and made the following conclusions. PO put a single wire ( sensor lead) in a poly tank. No ground. And fastened it in with home made brackets?

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I found a black wire to ground with an open connector on it at the front of the tank with the forward fuel lines.

The skid plate is being held by only 4 out of 8? Bolts and the poly tank is held in the middle by a single 2” metal strap. It wobbles up and down above the metal skid plate.

645EFDCE-F77F-4CA7-8470-02673F6695DB.jpeg

The rear bracket on the drivers side has a sharp corner which could easily puncture the tank in a minor accident.

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Looks like I have some work to do. I’ll try attaching a ground wire to the sensor plate. If that doesn’t work, change to an upgraded two lead sensor if I can mount it in the poly tank after the PO’s modifications.

Thanks again

[tgreese]

Home-made brackets - MTS uses pieces of aluminum like that to secure the sender. You can see them in picture 0022 here http://www.mtscompany.com/J-truck.htm They have installation instructions there, and offers a strap kit that somehow works with the tank. If the installation does not make sense, you could call MTS and ask them about the tank.

The original steel tank was suspended from the chassis, and the replacement plastic tank sits on the skid plate. Previously there would have been a pad or space between the skid plate and the tank. The strap that supports the tank now is the original restraint for the steel tank. There is also the Z-bracket that would have bolted to the welded edge of the steel tank. It could be removed. The tank also had a shield on the front corner that the installer may have discarded. That may address the puncture issue you bring up.

You definitely need a ground wire to the sender plate. Some senders have a tab for a push-on terminal. A ring terminal on your ground wire, under one of the screws, would probably work.

[devildog80]

Good you checked it out further.

Looks like you ran into more than you thought, and glad you are getting it fixed right

[aantalis]

Tim thanks. Everything you say makes sense. Feeling much better about tackling this project.

[aantalis]

Removed skid plate without disconnecting drive shaft, removed supply and vent hoses, siphoned tank, removed one strap bolt and lowered tank with a floor jack 4 inches to reach one of the fuel sensor fastening screw bolts, attached a ring terminal ground wire and voila! , I have a working fuel gauge!! Thanks again guys

[tgreese]

Woohoo!

[devildog80]

AWESOME news

How do the rubber hose connections look up there?

[akguy09]

My tank has a piece of 2x4 spacing it away from the bed, can't wait to drop it when I paint the bed to fix the PO mess on that one

[aantalis]

Hoses were old but in place and I didn’t desire to change them.
That 2x4 spacer might be keeping the sensor leads from jamming against the floor and shorting out.