fuel gauge not working..aftermarket plastic tank installed

[bizarro302]

Ok, so I recently purchased a 94 b3000 2wd, and a previous owner installed a plastic tank of unknown origin. I doubt the sending unit is even in it.

Probably wouldn't measure accurately anyhow as I doubt it's factory size. If I can figure out the capacity of the tank is there any way I can make the factory gauge work? Or even an aftermarket gauge?

I'm basically assuming the truck is getting 10mpg to be on the safe side and adding gas accordingly. Anyone got a real world number on what a 94 3.0 5speed 2wd gets for mileage with mostly city driving?

 

[RonD]

I would test if there is a sender in the tank

Usually there is a 4 wire connection going to the tank
Fuel pump power-pink/black strip wire
Fuel pump Ground- Black wire

Sender to gauge-yellow/white stripe wire
Sender ground-orange wire

Use an OHM meter from yellow wire(going to tank) to orange wire.
You will need to test this with fuel in tank at different levels, to get an idea of what sender is in there.

If you get infinite ohms(no connection) then sender is either not hooked up or not there.

This page has Ford and other types of ohm readings: http://www.fordification.com/tech/fuel-sending-units.htm

Your '94 factory gauge reads 16ohms as Empty and 158ohms as Full

There are universal senders that are adjustable for tank depth, but to use the factory gauge you must use one that has the 16 to 158 ohm range

 

[bizarro302]

Thanks man, I'm gonna have it up on a lift with basically a full shop available to me tomorrow and Monday. You pretty much just saved me from buying a Chilton/Haynes

Would a digital multimeter be able to measure ohms? I know there's one at the shop because i got one for my bro last Xmas. I've only used it to set gains to preamp output voltage on a car stereo install. So I'm not really sure what else it measures.

 

[Mdsune]

Yup mult-meters measure ohms


Sent from my iPhone using Tapatalk

 

[RonD]

Yes, as said, it will measure OHMs.
If it has multiple OHM settings pick the lowest one above 200 ohms,
So if it has 100 ohm setting and 1,000(1k) ohm setting use the 1,000

 

[bizarro302]

OK, so I got the truck up on my Bros lift, and I'm thinking the tank is factory. I was just taking previous owners word for it. It is plastic, but I know Ford used plastic tanks in some vehicles. I had a 99 escort with one.

The straps and fit look original, and it had a ford-esque part number on it. On the bottom center was "21" in larger font than the part number. So I'm assuming it's a 21 gallon.

I didn't have time to test the wires as I was addressing other issues on the truck that it needed to have replaced for state inspection.

My temp gauge also reads funky. It starts below C ,and never goes past a hair above C. Even on long trips while beating on it.

All other gauges i.e. speedo tach oil pressure, and voltage function fine.

Since those two are next to eachother I'm thinking they may be on the same harness?

On the 99 escort I had it all worked fine until I switched to a tach cluster. Then the fuel gauge didn't work. It always read half. In this case I know the sending unit was good since it worked prior to the swap.

Since this is reading below e at all times I'm thinking the gauge is OK, and it's either sending unit or wiring?

Am i on the right track here? Obviously I should test the wires at the sending unit.

 

[Haywire6000]

It's possible the float sunk. They are brass. My 93 had a pinhole in it.