Gas gauge question on 94 GT

[Clutch Cargo]

I purchased/installed a new Temp/Gas gauge for my 94 vert. The temp is working correctly. After installing I went down down to Costco and filled 'er up to make sure the gas gauge was working. It is, but I noticed when completely full the needle is almost 1/4 tank past the Full line. My old gas needle was maybe 1/8 past at best. Does this mean when I hit 1/4 tank I could be outta gas?

I know - I know, run down to E and see where I run out!

Always though old 94s worked on some sort of float system? Or do I need to somehow set the gauge? Thx.

 

[maillemaker]

Mine reads a good way past F when full also, and I don't think it's ever been fiddled with.

 

[ttocs]

yes it works on a float system that changes the resistance as it goes up/down.

Yes it is possible that someone has moved the needle and that you could run out prior to hitting E. It is never a good idea to run a tank dry because the last few gulps of gas will contain any/all the residue that has collected in the tank over time and it can clog your fuel sock/filter.

 

[maillemaker]

Not only that but the in-tank pump relies on being awash in fuel to keep it cool. Always a good idea to keep some gas in there so it stays submerged.

 

[Clutch Cargo]

So if I don't let run to E, as you guys warn, how will I know what is the tru E (or there abouts?) Right now I am just filling her up when it hits 1/4 full to play it safe.

 

[maillemaker]

I don't think running to E once and a while will hurt anything.

The fuel pump has a "sock" around the intake designed to act as the first filter in the system. It catches bulk crud in the tank.

 

[ttocs]

I don't think running to E once and a while will hurt anything.

The fuel pump has a "sock" around the intake designed to act as the first filter in the system. It catches bulk crud in the tank.

That is what I said. As long as you are ready do drop the tank and replace the sock or replace the filter that is the worst that should happen, as long as they do their job.

yes it works on a float system that changes the resistance as it goes up/down.

Yes it is possible that someone has moved the needle and that you could run out prior to hitting E. It is never a good idea to run a tank dry because the last few gulps of gas will contain any/all the residue that has collected in the tank over time and it can clog your fuel sock/filter.

 

[maillemaker]

Yeah, what I meant is I don't think the fuel level is going to have much to do with sediment getting caught in or on the sock. All fuel, and thus all particulates in the tank will end up at that sock no matter what.

 

[ttocs]

you can drive for years with a dirty tank but until you suck up that last little bit you will not get the really dirty gas until the end. Worst case scenario however is you end up trying to drop it with a full tank to replace the sock after you fill it back up and discover it is not running right.

 

[lwarrior1016]

Starving the pump can cause it to cavitate and that will damage the pump. It’s not so much sucking up trash, but really running it dry that’ll quickly kill it. Ask @white95 what just happened to his fuel pump.

 

[cobrajeff96]

It's possible the gauge/sender pairing is incorrect, from whoever you bought it from. They run on resistance values and they are specific to certain gauge cluster production runs. You might try contacting Mark Olson at Accutach.com, I'm sure he'd have a better answer than I would.

 

[ttocs]

To see how far off it is fill it up all the way, run it down to half a tank and see how much you need to put in to fill it back up.

As mentioned the resistance of the sender is important and our sn's use a strange resistance. If someone were to have replaced it with the wrong sender I would have thought you would have known by now.

Are there aftermarket gauges or a aftermarket gauge face on it? If so then someone pulled the needle off and it got put on just a tad off

 

[maillemaker]

I burned up the pump in my 1990 E350-based RV by running the tank low. First symptom was burned up fuel pump relay. Soon after that the pump burned up. Literally was slagged. Amazing that can happen in a tank full of gas! (no air = no boom)

 

[Clutch Cargo]

ttocs... good idea. When I get to 1/2 I will refill and see how many gallons it takes. Docs say my Mustang holds 15.4 gallons so hopefully it will refill at around 7 1/2. I bought the gauge used, but is not aftermarket. An original OEM. Thx cobrajeff. If after I fill is off I will use your contact. Maybe even have my mechanic drain the tank, clean it out and reset the gause if all is wrong?

 

[Mustang5L5]

If you can tap into the wiring and measure sender resistance the values are as follows.

EMPTY - 22 ohms
Full - 145 ohms.

So if it's reading 145ohms then the needle is incorrect. If it's higher resistance, then the senser is way out of spec.


Also, keep in mind often times the sensors are not linear due to the way the arm sweeps. For instance, mine stays at full for a while, but once the needle starts to move it drops quickly.

 

[white95]

Starving the pump can cause it to cavitate and that will damage the pump. It’s not so much sucking up trash, but really running it dry that’ll quickly kill it. Ask @white95 what just happened to his fuel pump.

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