Was wondering if anyone can assist me with fuel gauge troubles, I've replaced regulator & now have my oil & temp gauges working but still no fuel. I've just replaced sending unit in tank & have 50 ohms at
> sender which should be 3/4 tank or so. Ran a ground wire from sender
> to frame verified 5 volts at sender & if i ground 5 volts back there
> the needle will show full but needle only moves slightly up when
> hooked correctly. Any help would be greatly appreciated.
>
> Thanks
Don't know if you have seen this thread or not but it might trigger something to help you out.
https://forum.e-bodies.org/engine-transmission-and-rear-end/4/aftermarket-year-one-ss-fuel-sender-how-to-get-calibrated/7662/
Does the sending unit have the ground strap on the fuel line?
Quote:
I've just replaced sending unit in tank & have 50 ohms at
> sender which should be 3/4 tank or so.
The fuel sender range is 10 ohms full and 73 ohms empty, so at 50 ohms resistance, the gauge should indicate about 1/4 of a tank. For 3/4 of a tank you should be somewhere around 15 ohms to read correctly.
Quote from: Solarguy on August 02, 2018, 04:21:43 PM
Does the sending unit have the ground strap on the fuel line?
That factory strap is long gone but i ran a ground from the sending unit itself to the frame.
Quote from: 734406PK on August 02, 2018, 05:14:12 PM
Quote:
I've just replaced sending unit in tank & have 50 ohms at
> sender which should be 3/4 tank or so.
The fuel sender range is 10 ohms full and 73 ohms empty, so at 50 ohms resistance, the gauge should indicate about 1/4 of a tank. For 3/4 of a tank you should be somewhere around 15 ohms to read correctly.
Quote from: 734406PK on August 02, 2018, 05:14:12 PM
Quote:
I've just replaced sending unit in tank & have 50 ohms at
> sender which should be 3/4 tank or so.
The fuel sender range is 10 ohms full and 73 ohms empty, so at 50 ohms resistance, the gauge should indicate about 1/4 of a tank. For 3/4 of a tank you should be somewhere around 15 ohms to read correctly.
Thanks for that
Still looking for any ones ideas on whats going on with my fuel gauge... Is there a way to do an ohms test on the gauge itself ?
You've done a basic sweep test on the fuel gauge and it sweeps 100% from empty to full?
https://www.e-bodies.org/videos/
Try the clothes hanger wire trick if you have not. See the thread by kawahonda. I play with the wire a little, unplug the wire at the sending unit and push it in until it is seated good. I then poured in 5 gallons of fuel and the gauge reads a little more than 1/4 tank now. Before it was just pass empty even I got more than half tank of fuel in it. I will see how well it does once I get my car running.
Yes, you can check ohms with the gauge installed, the same way you check on the bench. Remove driver’s heat shield and plug some alligator clips to it after disconnecting it. If it’s 73ohms or higher and you KNOW that you have sufficient fuel in there, then A) your float has a leak or B) your float arm is caught at a weird angle prior to filling (try clothes hanger trick to give it a kick) due to the sender restraint tab not being perfectly optimized for the ebody tank depth. It’s either A or B at that point. A possible C) is that you didn’t test your sender before you put it and and it was DOA.
If you’re getting OHMs lower than 73 then your is correctly commicating that it has fuel. Then you need to focus on either a grounding issue, the gauge sender wire not being properly seated, or a gauge malfunction (which I would assume is rare).
That’s all there is to it!
Quote from: Cuda Cody on August 05, 2018, 10:42:06 PM
You've done a basic sweep test on the fuel gauge and it sweeps 100% from empty to full?
https://www.e-bodies.org/videos/
Yes i did... If i pull the 5 volts off of the sender & ground it then it'll shoot right up to full
I have tried the coat hanger with no results unfortunately.
Quote from: kawahonda on August 05, 2018, 11:41:11 PM
Yes, you can check ohms with the gauge installed, the same way you check on the bench. Remove driver's heat shield and plug some alligator clips to it after disconnecting it. If it's 73ohms or higher and you KNOW that you have sufficient fuel in there, then A) your float has a leak or B) your float arm is caught at a weird angle prior to filling (try clothes hanger trick to give it a kick) due to the sender restraint tab not being perfectly optimized for the ebody tank depth. It's either A or B at that point. A possible C) is that you didn't test your sender before you put it and and it was DOA.
If you're getting OHMs lower than 73 then your is correctly commicating that it has fuel. Then you need to focus on either a grounding issue, the gauge sender wire not being properly seated, or a gauge malfunction (which I would assume is rare).
That's all there is to it!
As it sits now it's showing 43 ohms at the sender itself so that should be enough to move the needle i would think.
If it's reading 43, then your sender is successfully telling the gauge "I HAVE FUEL!"
You can rule out the sender, no need to mess with it anymore.
The problem is either your gauge or the wiring. Most likely the wiring.
Next steps:
1) Bypass the grounding strap on the sending unit and ground it to areas on the chassis. Does it work now?
2) Hook up a multi-meter to your sending unit lead and check that you are getting pulsating 5Vs with the keyswitch on "On"
1) or 2) will tell you your issue.
I managed to crawl underneath the dash & with both posts disconnected measure 12 ohms across the gauge itself. Can anyone verify if that is correct.
Also is there supposed to be a ground on the gauge side somewhere that i'm overlooking ?
Quote from: kawahonda on August 06, 2018, 09:07:58 AM
If it's reading 43, then your sender is successfully telling the gauge "I HAVE FUEL!"
You can rule out the sender, no need to mess with it anymore.
The problem is either your gauge or the wiring. Most likely the wiring.
Next steps:
1) Bypass the grounding strap on the sending unit and ground it to areas on the chassis. Does it work now?
2) Hook up a multi-meter to your sending unit lead and check that you are getting pulsating 5Vs with the keyswitch on "On"
1) or 2) will tell you your issue.
I made up a jumper & grounded from the sender directly to the neg battery post & still nothing.
I also bypassed the wire from the gauge to the sender & ran a jumper & still nothing.
Also i replaced the factory voltage regulator with a solid state type & i'm measuring 5.05 volts solid non pulsating at the sender.
The Temp & Oil pressure work perfect with the new regulator.
Alright i found some information today, I bought a pack of resistors & bypassed the tank all together & ran a temp from the neg battery post through each resistor to the gauge & found that 8ohms is full & 32 ohms is empty and anything above 32 will hardly register.
I'm thinking the gauge must be at fault then
Are the resistors you used has the resistance rating at 5 volt? If it is rated at higher voltage then the resistance might be different at 5 volt. I am not very good at electrical but I kind of remember the gauge works off of current heating up element to move the needle. the 5 volt power is from the voltage regulator at the instrument panel. I supposed you checked your have 5 volts. May be Cody can chime in.
May be best to pull the sender to test and you can test the float if it is leaking. It is more work but not too bad. Sounds like your gauge is working when you ground it.
Quote from: Keith09 on August 06, 2018, 01:34:09 PM
Alright i found some information today, I bought a pack of resistors & bypassed the tank all together & ran a temp from the neg battery post through each resistor to the gauge & found that 8ohms is full & 32 ohms is empty and anything above 32 will hardly register.
I'm thinking the gauge must be at fault then
:iagree: The fuel gauge is bad. It should read Empty @70-73 ohms, 1/2 @ 23-25 ohms and Full @ 10-13 ohms. :bigthumb:
Quote from: 7212Mopar on August 06, 2018, 02:53:47 PM
Are the resistors you used has the resistance rating at 5 volt? If it is rated at higher voltage then the resistance might be different at 5 volt. I am not very good at electrical but I kind of remember the gauge works off of current heating up element to move the needle. the 5 volt power is from the voltage regulator at the instrument panel. I supposed you checked your have 5 volts. May be Cody can chime in.
Yes I replaced the voltage regulator with a new solid state type & I verified I'm getting solid 5.05 volts through the gauge.
I'm gonna pull the gauge in the next few days & bring it to an auto electric shop close by to verify before I spend more money needlessly.
Well i'm very happy to report i found the issue & it turns out was the gauge itself.
It would still sweep all the way full if i grounded it & was reading 12 ohms
The new one reads 17 ohms for anyone else looking to troubleshoot.
Great news! Equipped with the new solid state voltage regulator, you are better than new! :twothumbsup:
Thanks for posting the cause. A lot of times guys start a thread like this with no conclusion.
Quote from: RUNCHARGER on August 23, 2018, 06:48:07 PM
Thanks for posting the cause. A lot of times guys start a thread like this with no conclusion.
:iagree: Posting a successful repair can help other members with a similar problem. Congrats!