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fuel guage not working
- Thread starter CromeY90
- Start date
joe_peters
NAXJA Forum User
- Location
- Grants Pass, OryGun
The sending unit is a simple variable resistance device. On the Renix 0 ohms = empty, 44 ohms = 1/2; 88 ohms = full.
You can grab some resistors from RS and test the gauge. You can pull the sending unit and test it with an ohmmeter through its full range.
You can grab some resistors from RS and test the gauge. You can pull the sending unit and test it with an ohmmeter through its full range.
CamoChero
NAXJA Forum User
- Location
- Dallas, Texas
Well, with any vehicle of this age, if it has sat for any period of time the fuel can cause issues with the sending unit, try running some B12 fuel treatment through the system and see if that helps. Sometimes one use is enough to get the gauge to work sporadically. I had a 97 Sunfire that I had to use 2 fuel treatments with to get it working completely. Hope that helped...
- Location
- Rainy side of Washington
Yep, and OBD-I rigs (at least 91s and 92s) this is reversed and possibly slightly changed. My 91 MJ with an 88 MJ sender goes backwards and is nowhere near linear. 96 senders are one-of-a-kind, and 97-up I forget which way the resistance gradient goes.
I think we need to collect all this info into one post at some point. I'll have to poke around my FSMs sometime this evening if I find time.
- Location
- Rainy side of Washington
I wouldn't unless the assembly is extremely rusty, they're not a cheap part, try fixing it first.
Does it not work at all? Or just intermittent/reading makes no sense?
Does it not work at all? Or just intermittent/reading makes no sense?
old_man
NAXJA Forum User
- Location
- Loveland, Colorado
It is common for the plug on the back of the instrument cluster to corrode and cause intermittent results on any and all of the gauges. It is a ton easier to remove the cluster and clean the contacts to see if it fixes it, rather than pulling the sending unit.
sweet. i'ma try that on mine too:yelclap:
If 0 ohms = empty, then if the connecting wiring is shorted to ground gauge would read empty all the time.
Disconnect wire at tank end and get gauge reading (should read max) then short wire to a ground get reading (should read min)
If no change in reading:
Disconnect both ends, (tank & cluster) , and check wire for ohms to ground and continuety end to end.
If above reading is changing, then it looks like tank sender or connections at or inside tank are bad
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Could be the float on the tank sender arm has disconnected,gone bad or ?, and the arm is at the bottom and not changing with fuel level (constant 'empty' sent).
-----Suggest Joe's method in the above post with the resistors to narrow it down to if its in the tank or if it is forward.-------
Good Luck,
Orange
Disconnect wire at tank end and get gauge reading (should read max) then short wire to a ground get reading (should read min)
If no change in reading:
Disconnect both ends, (tank & cluster) , and check wire for ohms to ground and continuety end to end.
If above reading is changing, then it looks like tank sender or connections at or inside tank are bad
---------------------------------------------------
Could be the float on the tank sender arm has disconnected,gone bad or ?, and the arm is at the bottom and not changing with fuel level (constant 'empty' sent).
-----Suggest Joe's method in the above post with the resistors to narrow it down to if its in the tank or if it is forward.-------
Good Luck,
Orange
Last edited:
joe_peters
NAXJA Forum User
- Location
- Grants Pass, OryGun
Locate the sender's wire--the sender is a variable resistor, so if you put the resistors on the end of the sender's wire and touch to ground you will be sending the resistance value instead of zero resistance, which is what happens if you just touch the sender wire to ground directly.
- Location
- Rainy side of Washington
The black one should go to the pump body, that's ground. I believe reddish orange is fuel pump power but I'm not entirely sure... try the blue one.
Should be a 3 pin connector, just unplug the connector and (with the vehicle in park + ignition in RUN) touch the resistor to the pin for the black wire and the pin for the blue wire. If I'm right the gauge will come alive (or won't as the case may be), if I'm wrong, the resistor may... uh... get a little bit warm, be prepared to drop it. Then try it on the black wire and the reddish orange wire.
Should be a 3 pin connector, just unplug the connector and (with the vehicle in park + ignition in RUN) touch the resistor to the pin for the black wire and the pin for the blue wire. If I'm right the gauge will come alive (or won't as the case may be), if I'm wrong, the resistor may... uh... get a little bit warm, be prepared to drop it. Then try it on the black wire and the reddish orange wire.
so finally got time to work on the jeep today and i took the guages apart and all thje connections looked clean so i pulled the pump and what a suprize the float switch arm was seized on the low fule end and was all bent so changed it and wala my guage is atleast reading something now well see it it works the next chance i have to drive it see if the fuel goes down thanks to everyone for the advice
joe_peters
NAXJA Forum User
- Location
- Grants Pass, OryGun
Glad you got some progress.
Keep us updated.
Good luck.
Keep us updated.
Good luck.
