| Dustbowl | -- 09-04-2012 @ 6:30 PM |
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I am having trouble with the fuel gauge in my 36 Ford. Don't know if problem is with the dash gauge or the tank sender. To analyse, I measured current flow from gauge to sender as 0.25 amps. Does anyone know the correct current flow when tank is empty and when full?
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| MG | -- 09-04-2012 @ 6:36 PM |
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See this discussion - Click on link below: http://www.earlyfordv8.org/forum/viewmessages.cfm?Forum=18&Topic=4990&keywords=
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| supereal | -- 09-04-2012 @ 8:00 PM |
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What kind of trouble are you having? I knw many have posted complaints about the repro senders, but we have installed many of them successfully. The range is not as broad as the original K-S units, but with some fiddling with the float arm, they will do the job. They are a simple variable resistor with a wiper operated by the float. Often problems are due to a poor ground at the sender. We run a separate ground from the sender body to a known good ground as determined by an ohmmeter. As to the current, that is determined by dividing the voltage by the resistance. As the resistance varies as the float moves, there is usually no stationary current reading unless the float is still. When there is a problem, we remove the sender from the tank and connect it directly to the gauge. That will eliminate wiring as the cause, and verify the sender is working properly. If not, it is usually the gauge that is the problem.
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| TomO | -- 09-05-2012 @ 8:00 AM |
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To test the dash unit and the wiring, just ground the sending unit wire at the tank. The gauge needle should move towards the full mark. Do not leave this connected for more than a few seconds as the dash unit can be damaged. If your problem is in the tank unit, and it is an original King-Seely type, remove the unit and carefully remove the top cover. Carefully spray the contacts with tuner cleaner and operate the arm. Your ohm meter should read a very low resistance between the terminal and the case ground when the contacts are clean. Tom
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| Dustbowl | -- 09-05-2012 @ 11:26 AM |
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Thanks for good advice but no-one answered my question about current flow to sender at various float positions.
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| supereal | -- 09-05-2012 @ 2:20 PM |
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Reread my post above. It explains why there is no standard current flow. The purpose of the sender is to provide an analog current flow in proportion to the resistance provided by the position of the wiper on the resistance element. The current is quite low, so you can see it change when you put the ammeter part of a meter in series with the sender. Ford used gauges that move the needle with a bimetallic strip that flexes as it is heated and cooled. It s ideal for a gas gauge, as it eliminates the flutter that would result from sloshing fuel in the tank. Be sure the feed to the gauge is clean and tight, and that the full six volts is supplied.
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| TomO | -- 09-06-2012 @ 8:14 AM |
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Dustbowl, The current flow in the stock gauge circuit is not constant for any position of the float and I do not know of any specifications on the current flow. The flow in the gauge circuit is controlled by the amount of time that the contacts in the sending unit are closed. Current heats a bi-metal strip that opens and closes the contacts. The float controls the point gap. The sending unit points are opening and closing very quickly and the current flow bends a bi-metal strip in the gauge unit that move the needle. The after market sending units use a variable resister to affect the current flow to the gauge. These are not as accurate as the original units and tend to fluctuate more. Tom
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