93 ranger fuel guage / sending unit

[flboy0638]

Hello, first post here. I was wondering if I can ask a few questions and get someone to elaborate on "jumping a wire" to test the ohms of a sending unit while the sending unit is still in the tank. Firstly please take note of my issue. My fuel guage is not stuck, it does not bounce around constantly, it just moves from time to time an is inaccurate. When I unplug the harness the guage goes past full. I would like to know more about how to "jump" the circuit an test the ohms while unit is still in tank. I currently got 3/4 of a tank...

Questions:

Is the jump wire one piece of wire or two?

can I use a paperclip?

If one peice do I jump the prongs, the female connectors, or some other combination?

where exactly do i touch my multimeter in relation to this wire(s)?....... red on wire, black somewhere on frame?

Sorry, just a little more in detail on this procedure. trying to save some ridiculous money

 

[RonD]

You need an OHM meter and a siphon hose and/or gas can.

'89 and up Fords use 16-158 Ohm sending units and gauges
16 ohms Empty
158 ohms Full

Measure the sending unit OHMs, with 3/4 of a tank should be about 110 ohms, siphon out some gas or add some gas, OHMs should change, if OHMs are not changing then sending unit is bad.

When you unplugged the gauge it would have infinite OHMs(no connection) so gauge would go high(infinite is above 158), if you Ground that wire(0 OHMs) gauge should go below empty(0 is below 16).

 

[flboy0638]

On a 93' anyone know what color wires ( female or prongs ) I need to "jump" ?

How would I do this?

 

[flboy0638]

You need an OHM meter and a siphon hose and/or gas can.

'89 and up Fords use 16-158 Ohm sending units and gauges
16 ohms Empty
158 ohms Full

Measure the sending unit OHMs, with 3/4 of a tank should be about 110 ohms, siphon out some gas or add some gas, OHMs should change, if OHMs are not changing then sending unit is bad.

When you unplugged the gauge it would have infinite OHMs(no connection) so gauge would go high(infinite is above 158), if you Ground that wire(0 OHMs) gauge should go below empty(0 is below 16).

Thak you for the OHM specs for my year

 

[flboy0638]

based on this youtube I found

http://www.youtube.com/watch?v=aI3shtBhBk4

Look at the 5:00 minute mark

It looks like I have to jumper the first 2 "prongs" closest to the cab...

I guess I put my multimeter to the "ohm" setting and simply put the black to the left prong closest to the cab which is ground & put my red on the next over prong to get a present OHM reading ?

 

[cammeddrz]

I always just touch the yellow sending unit wire by the firewall connector with one lead, and put the other to ground. what's the need for "jumping" ?

is there something I don't know?

 

[flboy0638]

Im trying to see if the fuel sending unit is the issue before I go buy one.

 

[RonD]

based on this youtube I found

http://www.youtube.com/watch?v=aI3shtBhBk4

Look at the 5:00 minute mark

It looks like I have to jumper the first 2 "prongs" closest to the cab...

I guess I put my multimeter to the "ohm" setting and simply put the black to the left prong closest to the cab which is ground & put my red on the next over prong to get a present OHM reading ?

Yes that sounds about right, set meter to OHMs, 200 or higher, red and black probes don't matter for OHMs, there is no + or -
Yellow/white wire should be the sending units "out to gauge"
Orange wire should be sending unit ground

According to general ford wiring diagram, ford don't change wire colors much.

 

[flboy0638]

well i checked the ohms an they were right around 120 to 115 for 3/4 a tank.... So now Ill add gas an see if it changes. I assume if it changes as it suppose to then I got a bad ground or bad slosh module and should check that next?

 

[RonD]

Yes, it seems to be reading correctly since you assume 3/4 of a tank, 120 ohms is too close to be incorrect.
And sender issue is usually the float sinking, so you would see less than 25 ohms

I think the ground for the fuel pump and sender are by the inertia switch in passenger footwell/kick panel area

Anti-slosh module is on the back of the instrument cluster

 

[flboy0638]

boy ole boy am i a dummy. bought a fuel pump / sending unit today. 90 dollars. Put it in an the same issue. Tested old one by moving the float with multi meter on it. works just fine. I know I know "big dummy"

If anyone needs a good working fuel pump / sending unit email me at net0638@hotmail.com and Ill ship you mine for half price an shipping......

Im going to move on to the grounding issue now where you state for me to look:

"""""""I think the ground for the fuel pump and sender are by the inertia switch in passenger footwell/kick panel area"""""""""

 

[flboy0638]

Can you describe what it is I am looking for by the inertia switch?

DO I simply unscrew a ground wire like one would do on the back of a trailor when they need to clean up the contacts of a ground wire to get thier trailor boat lights to work?

 

[RonD]

Inertia switch should have a Pink/Black wire coming out, that's the power for the Fuel Pump, it should meet up with a Black wire and Orange wire these should be grounded near by the switch.
Also might see the yellow/white wire for the gauge.

This group of 4 wires goes to the Fuel tank connector.

 

[RonD]

boy ole boy am i a dummy. bought a fuel pump / sending unit today. 90 dollars. Put it in an the same issue. Tested old one by moving the float with multi meter on it. works just fine. I know I know "big dummy"

If anyone needs a good working fuel pump / sending unit email me at net0638@hotmail.com and Ill ship you mine for half price an shipping......

Im going to move on to the grounding issue now where you state for me to look:

"""""""I think the ground for the fuel pump and sender are by the inertia switch in passenger footwell/kick panel area"""""""""

I would keep the "old pump" handy, there has been a lot of recent posts about new, non-Ford, fuel pumps only lasting a month to a year, then failing.

 

[flboy0638]

can i cut the ground wire from the sending unit back at the tank an ground it somewhere back there instead of the long wire coming up front?

I did find some wires grounded in the footwell of the passengers side cab but they look fine.... Maybe its broke somewhere inbetween

again to reiterate my guage characteristics.... crank my truck an goes way past full. stays there, slowly moves back to where it needs to be over the course of 5 or so minutes, then fluctuates an moves around slowly....