Fuel gauge issues

[karayj]

Can some one tell me what these connection do?
1989 Regal Bow rider 3.7

I'm trying to figure out if I have a ground issue or a gauge issue basically what's going on now is I bought a fuel sending unit the new type that has the sending unit slide up and down this metal post I'll call it. No matter which way I connect the wires when I slide the sensor to the bottom as if the tank is empty my fuel gauge has full if I do the reverse and slide the sending unit upwards it says the tank is empty.

I went to reconnect my old gauge back and now the needle sometimes gets buried well well well beyond full if I jiggle the wires it'll say that it's full when there's actually only about 4 gallons in the tank . But the fact that I'm jiggling the wires got me confused.

I'm going attach some pictures maybe you guys can give me some advice so it's two parts when I connect the new sending unit it reads the system in reverse when I go to put the old good system back and hook it all up the needle goes down to a 5:00 o'clock position of o'clock then I reach underneath the dash again try to start shaking and jiggling things and sometimes it will go back to reading full but again it's not full it's only got 4 gallons . In the picture I see the blue wire should be power for the blub (not power) with test light. Orange wire is the sending unit . Black is ground . What is purple it dasey changes to the other gauges.

 

[alldodge]

Need some clarification

Merc uses Pink wire as the sender lead from the gauge
Black is ground
Normally Green is used as the bonding wire (which also goes to ground) but could be white

Where does the Blue wire go to?

The sender which was removed was a variable resistor type (240 ohms empty and 33 ohms full)

The sender your installing "appears" to be is the reed switch type. Don't know if the resistance and would need the part number?
How many wires does it have?

 

[karayj]

The "new" unit has 2 wires only . The blue wire seems to have to be power because it seems to be attached near the bulb. What I don't get is when I remove the ground and shake it , it seems to what to work but is way of on reading it correctly. Also with the new I could get it to work backwards now nothing . So I am trying to figure out where the failure is coming from. It has to be wiring issue to the gauge.

 

[alldodge]

Your previous sender may be a powered type, similar to Centroid products.

Need to understand what is there or could change over to the 2 wire type but this would take another gauge (if what you have is a powered sender)

 

[dingbat]

https://kus-usa.com/wp-content/uploads/2020/02/KUS-USA_SendingUnit_Installation_v4.pdf

Pink is ground, blue goes to sender

 

[karayj]

 

[dingbat]

Standard wire colors are not all that “standard”.

After 40 years in electronics manufacturing, I can tell you that making assumptions, especially with wire colors, is a fool errand. Never assume, verify

If the manufacturer of the sensors says pink is ground, pink is ground.

In your case, l will almost garuntee you the third wire is the grounding wire for the fuel tank. Gets connected in series with sender (pink) ground

 

[Bt Doctur]

In the 4th pic polarity does not matter Most show Black as the hot.
but unit should work in either direction.For the gauge, Blue is lighting, Purple is ign power, Black is ground, Pink to sender

 

[karayj]

SO can we all agree I need a new gauge with the new style fuel sending unit .
I want to make sure I do the right . So 5 is the blue wire in Pic 1 4 is nothing
3 is the orange or yellow wire that goes to the sending unit, 2 is black ground and 1 purple.

 

[alldodge]

Don't fully get the drawing, but would agree the best fix would be replace all and there should be no issue

 

[MichaelBC]

The wiring is quite simple and the colors don't really matter. So could it be that you just bought the wrong sending unit ?

There are two "standards" for this senders and gauges.
- 240 Ohms empty and 33 Ohms full (mostly US)
- 10 Ohms empty and 180 Ohms full (Europe)

So if you sender has the wrong standard and doesn't match the instrument it will show the wrong way round, just as you described it.

So you can buy a sender that matches your instrument or an instrument that matches you sender now.

I have also seen converters that can convert one signal to the other but this was more expensive than a new sender.

 

[Bt Doctur]

Is this gauge a stand alone or does it have 4 combined together cause your diagram makes no sense

 

[karayj]

I installed my new gauge with the new sending unit and all are working great. Thank you all for guidance.