Fuel and Temp gauge issues

-
Greg hailings

Greg hailings

Member
Joined
Sep 30, 2019
Messages
16
Reaction score
2
Location
Oklahoma
74 Dart Sport with gas and fuel gauge issues.

Replaced voltage limiter and the fuel gauge came on but it’s off by about 1/2 tank

I replaced sending unit and it reads the same ohms as the old sender at 24ohms while showing 1/4 tank on gauge (went with a 3/8 pick up reason for changing)

Testing at instrument plug shows 24 ohms as well

I have .1 ohm test on printed circuit board.

When testing from prong on board to terminal on gauge I get no continuity?

The temp gauge was showing 56ohms at sender (160 degrees under dash temp gauge)with 56 ohms at plug for dash. (the sender is for aftermarket gauge)

Tested circuit board the the same as above with same results.

Gauge not moving at all

Grounded both gauges and both pegged

At a loss now
 
Have a ground strap on the fuel sending unit to the metal fuel line?
 
You need to start by checking the gauges "in operation" with known resistances to simulate senders. Since you have an extra? fuel sender you can set that for desired resistance and then check the gauges. Both gauges should act the same with same sender resistance

Here is a photoshopped tester someone added in the resistances

c-3826-jpg-jpg.jpg


Make sure you are getting full battery voltage to IVR, and check carefully the resistance and condition of the IVR contact fingers to the board traces. Several of us have had to solder jumpers from the contact fingers to the traces.

Suspect connection problems at the gauge studs/ nuts. Loosen/ tighten them a few times to 'scrub' the connection.

It is always possible the IVR or gauges are defective

And make certain the harness connector pins are in good contact with board traces. Best to clean and solder all of them, or ate least check carefully for "loose"
 
After market senders have a lot of known issues with accuracy. They are not an accurate reproduction of the oem sender. Search on the forum and you will find lots of info.
 
Greg hailings said:
When testing from prong on board to terminal on gauge I get no continuity
Click to expand...
Sounds like you diagnosed your problem... Loose pins.
This cluster is measuring 3.8 ohms between pins and the pins are tight.
The fuel guage pins measure 0.4 ohms and feel just as tight.

15921527303739197568451275549527.jpg
15921527502894941407992533517389.jpg
 
Mike69cuda said:
After market senders have a lot of known issues with accuracy. They are not an accurate reproduction of the oem sender. Search on the forum and you will find lots of info.
Click to expand...




Checked again from prong to gauge tested .2 ohms

showing 26 ohms at harness plug but only showing 15 ohms at gauge when plugged to board

temp gauge I ran a jumper from sender direct to gauge no movement.

I have a spare set of gauges I hooked direct to sender as well grounded and used 5 volts to power and nothing

did same with fuel gauge and used sender and they both ohm the same and gauges move according

Dana67Dart said:
Sounds like you diagnosed your problem... Loose pins.
This cluster is measuring 3.8 ohms between pins and the pins are tight.
The fuel guage pins measure 0.4 ohms and feel just as tight.

View attachment 1715545594 View attachment 1715545595
Click to expand...
 
Greg hailings said:
Checked again from prong to gauge tested .2 ohms

showing 26 ohms at harness plug but only showing 15 ohms at gauge when plugged to board

temp gauge I ran a jumper from sender direct to gauge no movement.

I have a spare set of gauges I hooked direct to sender as well grounded and used 5 volts to power and nothing

did same with fuel gauge and used sender and they both ohm the same and gauges move according
Click to expand...

You are going to have to be more specific about where to where you are connecting your meter

You can use a fuel sender to check any gauge, oil, temp, fuel, just set the sender to the desired resistance. When you get a setup that won't work check for voltage in order.......from IVR output.........to the terminal on the gauge hooked there.......through the gauge........and to the sender. If for example, you read 5V at the sender, you know the sender is losing contact. If the IVR 5V goes away, you know there is something wrong right there, in the IVR itself or the contacts where it fits

DONT FORGET TO GROUND THE CLUSTER when testing
 
I'm still trying to decipher what has been said. One temp sender for a different aftermarket temp gauge and both temp gauges attached to that one sender? I don't think that will work. I dont know what the aftermarket gauge has for power supply. If on a 12 volt supply, what back feed issues might occur?
If a good fuel gauge gets the right voltage in and through it, 23/24 ohms should take that needle to 1/2. Move that blue wire to in place of the purple temp sender wire / pin and that temp gauge should go to half also. That could prove your aftermarket temp sender and gauge are the root of problems. good luck with it.
 
RedFish said:
I'm still trying to decipher what has been said. One temp sender for a different aftermarket temp gauge and both temp gauges attached to that one sender? I don't think that will work. I dont know what the aftermarket gauge has for power supply. If on a 12 volt supply, what back feed issues might occur?
If a good fuel gauge gets the right voltage in and through it, 23/24 ohms should take that needle to 1/2. Move that blue wire to in place of the purple temp sender wire / pin and that temp gauge should go to half also. That could prove your aftermarket temp sender and gauge are the root of problems. good luck with it.
Click to expand...

Temp:
I warmed the car to about 170 on aftermarket gauge Unhooked and hook the stock gauge up and didn’t move. (Hooked to the aftermarket sender that came with the 12 volt gauge)

I jumped from fuel sender wire 28 ohms to back of temp gauge no movement



Tested out of car using spare fuel sender as you suggested. Put together several AA bats to get 5-6 volts to power gauge and The gauge worked.

could it be the 12 volt gauge sender not compatible with stock gauge




Fuel:
At the main female harness plug it shows 28ohms 29 at sender at tank
Once plugged to pin on cluster it shows 18 at pin and 18 at gauge
All pins tight
Gauge reading 1/4 tank
 
Last edited:
You are not "listening." I already advised you to be more specific. When you make some test or measurement, it's not helpful to say "put my meter on the prong." Prong of WHAT. You need to type out exactly what you did, what you connected to and under what conditions. Much of what you said in your posts is meaningless, and we are guessing
 
"sender not compatible with gauge"

That does not matter. I already posted re: the gauge tester. You set the gauge up with a KNOWN proper power supply, that is a working IVR supplying the gauge, in the cluster just like it was "running" and you substitute a sender SET AT KNOWN TEST RESISTANCE as shown in the photo re: the tester. Those resistances should produce known gauge readings, IE "empty" "half scale" and "full" with the three resistance settings. You get that working. You check the wiring. And then you worry about what the sender is doing.
 
Greg hailings said:
Temp:
I warmed the car to about 170 on aftermarket gauge Unhooked and hook the stock gauge up and didn’t move. (Hooked to the aftermarket sender that came with the 12 volt gauge)

I jumped from fuel sender wire 28 ohms to back of temp gauge no movement



Tested out of car using spare fuel sender as you suggested. Put together several AA bats to get 5-6 volts to power gauge and The gauge worked.

could it be the 12 volt gauge sender not compatible with stock gauge




Fuel:
At the main female harness plug it shows 28ohms 29 at sender at tank
Once plugged to pin on cluster it shows 18 at pin and 18 at gauge
All pins tight
Gauge reading 1/4 tank
Click to expand...
TEMP
I have no idea what the ohms range of your aftermarket sender is. All OEM senders operate on 80-10 range.
Entire circuit resistance will be different from senders resistance. There is a ground path back through the limiter of complete circuit. Gauge tests only cover 3 different needle positions. I can tell you 1/4 tank should be close to 34 ohms. 29 ohms would be somewhere between 1/4 and 1/2. That 29 ohms would move a temp gauge needle to about the same position of a temp gauge screen. Up into normal range, approx' 190 degrees.
All of this is dependant on what voltage is being supplied. The solid state 7805 regulators with input of 9 volts minimum, 35 volts maximum will put out 4.9 to 5.3 volts, (changes as it heat up), 1.5 amps, and gauges may read just a little bit low. A new mechanical limiter made in Mexico or China,,, I have no idea how much voltage comes out of that or what effect low input voltage will have on its output voltage.
One switched hot wire feeds oil warning lamp, brake warning lamp, and the limiter. Then there should be a noise suppression cap plugged in with the center 12 volt spade of a mechanical limiter. I dont know if those can go bad and wick away voltage.
So... Maybe a OEM correct sender will correct temp gauge operation. I don't know how much fuel you have in the tank or what you expect that gauge to show. Most do have to add a meter match module to these aftermarket fuel senders regardless of what limiter or regulator they use for power supply. hope this helps
 
You must log in or register to reply here.
-

Back
Top