86' Fuel Issue

[Mendo4Runner]

Hey, new to this forum and my first post.

I am a owner of a 86 4runner. I am the third owner, and it does not have a working fuel gauge. The fuel gauge works sometimes, but often only when the tank is full, which leads me to believe that the Fuel Sending Unit needs to be serviced and thus the tank needs to be dropped to investigate. My dilemma is, I do no know the capacity of my fuel tank, only have an estimate that it is probably a 14.8or 9. I want to fix this problem, but do not know what to do because there is no known OEM or aftermarket manufacturer for the part. When the tank is dropped, I want to have a replacement part to give a mechanic/my friend IF the part needs to be replaced. Anybody have any experience with this? Should I really attempt to drop the tank on my own without a replacement float or sending unit? Do any universal sending units actually work for this tank/vehicle/make/model?

Thanks-

 

[fourwd1]

If it partially works, you can disassemble it and clean it if the windings aren't too bad, and it may be OK.

 

[KidVermicious]

Couple things - mine did the same thing after I had it sitting for awhile, flaky gauge would cut out when the tank got low, but the low fuel light was always accurate. It started working again after I ran a few rounds of fuel cleaner through it.

If that doesn't help, you'll want to clean out/replace the sender, but you don't need to drop your tank. There's an access panel underneath your rear seat that opens right on top of the fuel pump/sender assembly.

 

[fourwd1]

The fuel pump/pick-up and the gauge sending unit are two different things located in two different areas of the tank.

There's really no way fuel additives could fix the gauge sender, as the potentiometer windings do not contact the fuel.

 

[KidVermicious]

The fuel pump/pick-up and the gauge sending unit are two different things located in two different areas of the tank.

There's really no way fuel additives could fix the gauge sender, as the potentiometer windings do not contact the fuel.

Thanks for the correction, mine must have come clear on it's own.

I dunno if the OPs low fuel light is working like mine was... any idea why the needle registered intermittently but the low fuel light worked reliably?

 

[fourwd1]

The low fuel switch and the fuel level sender are parts of th same assembly, but work independently, so one could work but not the other. The level sender is a wire wound potentiometer, but the low level is a simple switch that is part of it. The windings on the "pot" get dirty and therefore intermittent. The switch is either Go or No-Go (works or doesn't).
Hopes this helps explain it

 

[Mendo4Runner]

Thanks guys,

But, I am still confused. So I will still need to drop the tank to service the part right? Is the sending unit screwed on or in a lockring? Does anybody really know if those universal senders will work? Can I tell the capacity of my tank by looking at it? I cannot access a VIN number and have yet to just run it out of gas.

Thanks

 

[KidVermicious]

Thanks guys,

But, I am still confused. So I will still need to drop the tank to service the part right? Is the sending unit screwed on or in a lockring? Does anybody really know if those universal senders will work? Can I tell the capacity of my tank by looking at it? I cannot access a VIN number and have yet to just run it out of gas.

Thanks

I feel like a tool for telling you wrong earlier, so I went and looked. There's a set of wires coming out of an assembly at the rear top of the tank. I saw mine real easy cuz my spare isn't in and I'm lifted a little. If you're stock, pull the spare and jack up the rear, you'll see what I'm talking about.

Look here. Exactly what fourwd1 said, with pictures and detail, and some tips on finding a replacement sender. They seem to think you need to drop the tank. It looked to me like maybe you could get away with just removing the rear bolts and supporting the tank with a tranny jack? But if you can't work the float bar in that way, or if the filler tube assembly won't let you, then you'll need to drop the tank.

On the plus side, if you drop the tank, you can measure its capacity for yourself, and get high off the fumes to boot.

 

[Mendo4Runner]

Thanks man,

I'm just trying to figure out as much about this issue as I can, (I am still waiting for my Chilton's to come in the mail) and will let you know if I make any headway. I have a bit of a lift, def not stock. I wish I knew more really, I am coming from several stock Toyota's to my first lifted, 4x4. It's kind of silly really.

Cheers,

Pete

 

[Mendo4Runner]

Oh man,

That thread just blew my mind. I have been scanning the internet for a week looking for answers. Thanks!

Replacement fuel sending units for these, as far as I know, do not exist. So, I will probably have to pull the old one if I cannot fix it by cleaning it, especially if the resistor is worn. It looks like I am facing the possibility of adding a aftermarket fuel sending unit with an accompanied aftermarket fuel gauge. The voltage I guess if different so I would need to use a new gauge. I will update you on how this works out.

Cheers,

Pete