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Ford Gas Gauge problem


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sc222
User

Jun 8, 2012, 2:36 PM

Post #1 of 19 (1319 views)
  post locked   post icon Ford Gas Gauge problem  

New here. Hope I provide enough info.
1990 Georgie Boy motorhome on a Econoline chassis. 460 CID, 40K miles.
Gas gauge failed suddenly. Removed connector at tank to ground it out and determine source but when I removed the electrical connector and turned the key on the gauge went to over full before I had grounded any of the wires. I reconnected the connector at the tank and the gauge went back to empty. The connector at the tank has 3 wires. I measured 8 volts in one of them? The other two had no voltage of course. Grounding them out did NOT make gauge read full again. I could not see any breaks in the wires/insulation but it was easy to have missed something.
Thank you for any help you can provide.

sc222


Tom Greenleaf
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Jun 8, 2012, 2:57 PM

Post #2 of 19 (1293 views)
  post locked   Re: Ford Gas Gauge problem  

So far this suggests dash gauge is good. HOPE OTHERS JUMP IN HERE for this! Watch out grounding stuff like that even as old as 1990 it could cause problems you don't want. Another thing that would help is do you know if this is an original gas tank by Ford or custom somehow for more fuel or something and if they do that to make some motorhomes and who knows as there are plenty of alterations possible,

T
_________________________________________
Long retired now


Hammer Time
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Jun 8, 2012, 3:03 PM

Post #3 of 19 (1285 views)
  post locked   Re: Ford Gas Gauge problem  

It went to full when you unplugged it. Did it go to empty when you grounded it?



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sc222
User

Jun 8, 2012, 3:10 PM

Post #4 of 19 (1281 views)
  post locked   Re: Ford Gas Gauge problem  

Thanks for the interest.
No, it did not go to empty when I grounded it.


Hammer Time
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Jun 8, 2012, 3:16 PM

Post #5 of 19 (1276 views)
  post locked   Re: Ford Gas Gauge problem  

You would need to jump the yellow with white wire to the black wire and it should go the opposite direction. The black wire should be a good ground.
You can also measure the resistance of the sender itself. It should read 70 ohms empty and 10 ohms full.



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(This post was edited by Hammer Time on Jun 8, 2012, 3:17 PM)


sc222
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Jun 8, 2012, 3:19 PM

Post #6 of 19 (1270 views)
  post locked   Re: Ford Gas Gauge problem  

I don't mean to be thick but I want to get this right.

Jump the yellow (hot) to the white and the black? Connect all three together and the gauge should go from full to empty?
If this occurs as predicted does it pretty much nail down my sender unit as the culprit?


Hammer Time
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Jun 8, 2012, 3:23 PM

Post #7 of 19 (1265 views)
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Quote
Connect all three together


Where did I say anything about 3 wires. I gave you the specific wire colors to join? The proper way to do this would be to use the correct resisters between those 2 wires to be more accurate.



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sc222
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Jun 8, 2012, 3:34 PM

Post #8 of 19 (1256 views)
  post locked   Re: Ford Gas Gauge problem  

Okay, I jumped the Yellow/White to the Black wire. Gauge remained above full. No fluctuation.


Hammer Time
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Jun 8, 2012, 3:56 PM

Post #9 of 19 (1240 views)
  post locked   Re: Ford Gas Gauge problem  

You really should test this with resisters to get an accurate test but is sounds like either the dash gauge is bad or there is a short in the wiring somewhere. High resistance or open circuit should send it to empty but you need to test it with the proper amount of resistance.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Discretesignals
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Jun 8, 2012, 4:24 PM

Post #10 of 19 (1232 views)
  post locked   Re: Ford Gas Gauge problem  

Just curious, but does this have dual tanks?





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sc222
User

Jun 9, 2012, 10:01 AM

Post #11 of 19 (1192 views)
  post locked   Re: Ford Gas Gauge problem  

No, single tank. I have removed the instrument cluster and plan to learn how to test it or have someone do it. It is only a 10 minute job.


sc222
User

Jun 10, 2012, 10:37 AM

Post #12 of 19 (1163 views)
  post locked   Re: Ford Gas Gauge problem  

Off to buy a resistor as Hammer Time suggested. See if this sounds correct. I will buy a resistor somewhere in the middle of the 70 ohm and 10 ohm range HT provided. Will put resistor in place of sending unit at the connector that connects to the tank. One end of resistor to gnd the other to yellow/white. If gauge reads consistent with the resistor then my sender is bad. If not, the wiring or gauge is bad.
Next I will test the gauge by connecting resistor to grnd and to yellow/White wire where it comes out of the cluster. If gauge works then wiring is bad. If gauge fails then gauge is bad.

This is a stretch for me. Is my logic sound? I keep reading about a voltage regulator. I believe this is connected to the back of the cluster directly behind the fuel gauge?


Hammer Time
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Jun 10, 2012, 10:44 AM

Post #13 of 19 (1159 views)
  post locked   Re: Ford Gas Gauge problem  

No, you should be buying 2 resisters, one of both of those values so it can be tested for both full and empty.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



sc222
User

Jun 10, 2012, 11:12 AM

Post #14 of 19 (1154 views)
  post locked   Re: Ford Gas Gauge problem  

As I said, this is a stretch but want to learn. Do I get 1/2 watt resistor? 1/4 watt or does it matter. At RS now and kid knows less than me.


Hammer Time
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Jun 10, 2012, 11:15 AM

Post #15 of 19 (1148 views)
  post locked   Re: Ford Gas Gauge problem  

Where are you getting this stuff? Resisters aren't measured in watts.
You need a 70 ohm and a 10 ohm resister.
One should read full when inserted and one should read empty when inserted.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



sc222
User

Jun 10, 2012, 11:30 AM

Post #16 of 19 (1143 views)
  post locked   Re: Ford Gas Gauge problem  

I realize they aren't measure in watts. However they sell 10 ohm resistors that are 1 watt, 1/2 watt and 1/4 watt. I am getting this from the selection drawers at RS. Happy to send pic of resistor rates for different watts if you want. Check here links deleted..... not allowed

In Reply To


(This post was edited by Hammer Time on Jun 10, 2012, 11:35 AM)


Hammer Time
Ultimate Carjunky / Moderator
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Jun 10, 2012, 11:37 AM

Post #17 of 19 (1137 views)
  post locked   Re: Ford Gas Gauge problem  

Thery are probably rating how much current they can carry. That's not real important for this test.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



sc222
User

Jun 10, 2012, 11:48 AM

Post #18 of 19 (1133 views)
  post locked   Re: Ford Gas Gauge problem  

Thanks. However since the units are watts it would be referring to power not current because current is measured in amps. "where do you get this stuff?" Smile


Hammer Time
Ultimate Carjunky / Moderator
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Jun 10, 2012, 12:02 PM

Post #19 of 19 (1126 views)
  post locked   Re: Ford Gas Gauge problem  

OK, we're done here.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.





Ford Gas Gauge problem


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