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How best to test a fuel sender off the car?
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Sorry - should have added that I have a multimeter and when i connect the leads to the using the OHM setting I get a reading of "1" initially and then it goes to nearly zero on the first sending unit. That indicates that I have flow through the gauge and that it will probably work? Yes/no?
TR3driver
Great Pumpkin - R.I.P
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On a TR2-3B, the resistance should be nearly zero with the float at the bottom. On a TR4-6, resistance should be nearly zero with the float at the top.
Some digital meters do read '1' with the other digits blanked, to indicate out of range. However, the fuel sender on a TR2-3B should never go full open, and I think the same applies to the TR4-6. If it does, the sender is defective and probably will only work through part of the range.
My suggestion would be a new sender; but you've got nothing to lose but time (and sanity) trying to repair the old one. Open it up carefully, find the broken wire, clean the broken ends and twist them together securely. The wire will be Nichrome or similar, which is usually impossible to solder.
If you are really crazy, you can even remove the old winding and try to replace it. You'll need to find resistance wire with the same resistance per foot, and then duplicate the original winding.
Some digital meters do read '1' with the other digits blanked, to indicate out of range. However, the fuel sender on a TR2-3B should never go full open, and I think the same applies to the TR4-6. If it does, the sender is defective and probably will only work through part of the range.
My suggestion would be a new sender; but you've got nothing to lose but time (and sanity) trying to repair the old one. Open it up carefully, find the broken wire, clean the broken ends and twist them together securely. The wire will be Nichrome or similar, which is usually impossible to solder.
If you are really crazy, you can even remove the old winding and try to replace it. You'll need to find resistance wire with the same resistance per foot, and then duplicate the original winding.
Tinkerman
Darth Vader
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Remember all we are testing here is continuity. It should read 0 or infinity on the ohm meter. As you move the float it should be at infinity because you have continuity. Are you connecting the leads to the gas gauge itself or to the connections on the sending unit?
Go to: https://mgaguru.com/mgtech/electric/fg_01.htm for a full discussion on the gauge itself.
Tinkerman
Go to: https://mgaguru.com/mgtech/electric/fg_01.htm for a full discussion on the gauge itself.
Tinkerman
TR3driver
Great Pumpkin - R.I.P
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Uhm, Dick, "continuity" would be zero ohms, "no continuity" infinite.
But the thread is about how to test the sender, and IMO checking only for continuity is a poor way to do that. Senders "wear out" because the resistance wire rubs through, which both changes the resistance and eventually causes the wire to break.
Note that Barney's excellent article is written for an MGA; the TR2-3B gauge is very similar but not identical. And the TR4-6 gauge (I'm still not sure which one Tom is working on) is totally different.
But the thread is about how to test the sender, and IMO checking only for continuity is a poor way to do that. Senders "wear out" because the resistance wire rubs through, which both changes the resistance and eventually causes the wire to break.
Note that Barney's excellent article is written for an MGA; the TR2-3B gauge is very similar but not identical. And the TR4-6 gauge (I'm still not sure which one Tom is working on) is totally different.