Troubleshooting your fuel level sender

***TitaniumTT*** · 01-10-2014, 08:02 PM

Yup.... the thing died Labor Day weekend and I've driven her maybe a handful of times when other cars have been a PITA or Maggie needed my Jeep for a week... aside from that she's been in "storage."

Thinking about how moving one lever independently of the other and going through the math in my head, yes, it's simple math and averaging. The thing to worry about though is when on the track, and when the drivers side pukes.

JL1RX7 · 01-10-2014, 08:13 PM

Hard to say if they are using the computer to do the averaging or if it is true resistance that doing the work. It's been awhile since I read a cut sheet on level sensor. Most of the time the ones I work with are high or low level limit switches. Next week when I am bored I will read up on them.

Sinfidelity · 07-12-2015, 12:41 PM

Quote:

Originally Posted by JL1RX7

Hard to say if they are using the computer to do the averaging or if it is true resistance that doing the work. It's been awhile since I read a cut sheet on level sensor. Most of the time the ones I work with are high or low level limit switches. Next week when I am bored I will read up on them.

I've been taking readings all week from the right side sender in order to get the right sender in my new lpg tank.

The readings below.

Fuel gauge reading
Full 47ohm
3/4 210ohm
1/2 243ohm
1/4 326ohm
Empty 326ohm

So I'm guessing this is not gonna be accurate if rx8 somehow averages out from two senders?
I noticed the reading of 326 never changed between below half and empty !!? Drove me crazy
Maybe the two senders merge their wires parallel and cld be measured at that point?

Sinfidelity · 07-13-2015, 09:49 AM

So today I followed the wiring back to cluster.
Turns out the two senders share the black/ brown trace and send the other two wires along with a single merged black/yellow-ish trace back to cluster.
So a total of 3wires go directly to cluste from the two senders.
I pulled the two plugs from a spare loom and twisted the unshared two wires (one from each sender) ( blue/red trace and white /green trace) together.
Filled the tank and measured impedience basically as parallel from both senders and got 9ohms which I believe what is stated in the SM.
ILL test at all the gauge increments to see if it seems consistent and post results.
I don't think the ecu is making any calculations what so ever as the car I traced these wires to cluster had no ecu attached.

RICE RACING · 07-13-2015, 06:01 PM

good thread, should be more like this!

Sinfidelity · 07-17-2015, 02:40 AM

Damn it's weird!

So I cut out the fuel sender plugs n cable from an old loom to use as a test cable enabling me to read my running car and test in parallel, solo and in series to try figure this out.

All seemed to be good till I hit half tank while testing both senders parallel
Full 7-9ohm
3/4 55ohm
1/2 94 ohm
1/2 142 ohm left side only

Not sure what to follow here seeing as the right side isn't gonna change now till empty.

JL1RX7 · 07-17-2015, 04:06 AM

Now since it is a averaging sensor I wonder if it only takes input from certain OHM readings. So say anything above 90 OHM it only reads from one side vs the other.

Most of the sensor's I use are for temperature across a large area. Not a split sensor system like this. But trying to see the logic of what they are trying to read, then using a sensor to read it. I could see it doing something like that.

01-10-2014, 08:02 PM	#1
*TitaniumTT* Test Whore - Admin Join Date: Mar 2008 Location: Right Behind you son Posts: 4,581 Rep Power: 10	Yup.... the thing died Labor Day weekend and I've driven her maybe a handful of times when other cars have been a PITA or Maggie needed my Jeep for a week... aside from that she's been in "storage." Thinking about how moving one lever independently of the other and going through the math in my head, yes, it's simple math and averaging. The thing to worry about though is when on the track, and when the drivers side pukes. __________________ -The Angry Stig- DGRR 2009, 2011, 2012 & 2013 - Best FC DEALS GAP!! WOOHOOOO!!!!! 2015 Audi S4 - Samantha - Zero Brap S4 2004 RX8 - Jocelyn - 196rwhp, 19mpg fuel to noise converter 2000 Jeep Cherokee Sport - Wifey mobile - Now with 2.5" OME lift and 30" BFG AT KO's! So it begins 1998 Jeep Cherokee - 5 spd, 4" lift, 33" BFG's - Rotary Tow Vehicle 1988 'Vert - In progress 1988 FC Coupe - Gretchen -The attention whore BEAST! I'm a sick individual, what's wrong with you? I'm pure Evil I'm still insane, in the best possible way. I think Brian's idea of romance is using lube. Your rage caused the meteor strike in Russia. The Antichrist would be proud of his minion. You win with your thread. Most everything It's a truck with a steel gate on the back. Just a statement of fact Motec M820, AIM dash, ported 13B-RE Cosmo, 6-spd trans, 4.3 Torsen, custom twin wg fully divided mani, Custom 4" split into 2x 3" exhaust, Custom HMIC, Custom custom custom custom I like to welder stuff.... No Bolt-ons allowed. Dyno'ed @ Speed1 Tuned by me - 405rwhp on WG.... WM50 cuming soon. *-Angry Motherfcker Mode ENGAGED-**

07-13-2015, 06:01 PM	#5
RICE RACING Don Mega Join Date: Dec 2008 Location: Utopia Posts: 1,688 Rep Power: 18	good thread, should be more like this! __________________ www.riceracing.com.au Worlds best Apex Seals Coil on Plug Water Injection ECU Calibration

Thread Tools
Show Printable Version Email this Page
Display Modes
Switch to Linear Mode Hybrid Mode Switch to Threaded Mode

01-10-2014, 08:13 PM	#2
JL1RX7 Rotary Fanatic Join Date: Feb 2008 Location: Front Royal, VA Posts: 487 Rep Power: 18	Hard to say if they are using the computer to do the averaging or if it is true resistance that doing the work. It's been awhile since I read a cut sheet on level sensor. Most of the time the ones I work with are high or low level limit switches. Next week when I am bored I will read up on them.

07-13-2015, 09:49 AM	#4
Sinfidelity The Newbie Join Date: Mar 2014 Posts: 4 Rep Power: 0	So today I followed the wiring back to cluster. Turns out the two senders share the black/ brown trace and send the other two wires along with a single merged black/yellow-ish trace back to cluster. So a total of 3wires go directly to cluste from the two senders. I pulled the two plugs from a spare loom and twisted the unshared two wires (one from each sender) ( blue/red trace and white /green trace) together. Filled the tank and measured impedience basically as parallel from both senders and got 9ohms which I believe what is stated in the SM. ILL test at all the gauge increments to see if it seems consistent and post results. I don't think the ecu is making any calculations what so ever as the car I traced these wires to cluster had no ecu attached.

07-17-2015, 02:40 AM	#6
Sinfidelity The Newbie Join Date: Mar 2014 Posts: 4 Rep Power: 0	Damn it's weird! So I cut out the fuel sender plugs n cable from an old loom to use as a test cable enabling me to read my running car and test in parallel, solo and in series to try figure this out. All seemed to be good till I hit half tank while testing both senders parallel Full 7-9ohm 3/4 55ohm 1/2 94 ohm 1/2 142 ohm left side only Not sure what to follow here seeing as the right side isn't gonna change now till empty.

07-17-2015, 04:06 AM	#7
JL1RX7 Rotary Fanatic Join Date: Feb 2008 Location: Front Royal, VA Posts: 487 Rep Power: 18	Now since it is a averaging sensor I wonder if it only takes input from certain OHM readings. So say anything above 90 OHM it only reads from one side vs the other. Most of the sensor's I use are for temperature across a large area. Not a split sensor system like this. But trying to see the logic of what they are trying to read, then using a sensor to read it. I could see it doing something like that.