Fuel sending unit

[jimmys67]

About 9 months ago, I installed one of these aftermarket fuel sending units from ebay for a 1967 Plymouth Valiant. At the time I thought that the new unit would come with a new ground strap. It didn't. So I created another type of ground which worked for a few months. Then the gauge stopped working again. I bought a ground strap, and from there the gauge would work sporadically. I've cleaned the connections between the sending unit and the gas line above the rubber hose. Now I get nothing at all.
I checked the continuity of the sender wire and it is fine. I also created a "good" ground and still nothing.
After all of this I checked the sending unit with an ohms meter. It read 0.00 everytime. As I released contact from the terminal, I would get a flashing of an ohms reading. But with solid contact. It was always 0.00. I would have to think that the sending unit is bad, even though being 9 months old. The wiring going to the sending unit seems to be good. My only thought is that it is the sending unit itself is bad. Please help with any suggestions. Thanks.

jimmys67

 

[nm9stheham]

Any help in this yet? if not:

1. Check the setting of your ohmeter scale selection. Make sure it is on the lowest ohms scale, probably 200 or 400 (varies with meter brand). Make sure it is not on a scale that ends in 'k'; the k stands for 1000 and you will be trying to measure thousands of ohms, not the 10 to (approximately) 75 ohms of the sender. 10 ohms on a 20,000 ohms scale will read 0.00 or 0.01; that is not adequately accurate.
2. When on that low scale, check you meter by first shorting the leads together; you should read nearly 0 ohms. Then un-short the leads and the meter should show a non-numeric reading, indicating an open circuit.
3. Measure the sender's resistance from the sender connection to ground with the wire disconnected. You should read around 10 ohms full, 25 ohms at 1/2, and around 73 ohms near empty.
4. Change the meter setting to DC volts at a scale of 20 or so. With the wire disconnected from the sender, turn on the ignition to RUN, and measure the voltage on that wire; it should bounce back and forth from 0 to 12v and numbers in between.
5. Does your temperature gauge read normally? It runs from the same voltage source in the cluster, and if it is good, then that part of the circuit is good (the voltage limiter).
6. Make sure you have a good ground at the insrutment cluster too.
7. Is your ground strap from the sender to the car's chassis? That is better than to the main fuel line.

 

[jimmys67]

Dear Sir, All excellent advice. Thank you very much. I'll have to wait till the weekend to work on the car. When I figure it out, I'll post back. Thanks again.
I see that you're in Waynesboro. Is that in Virginia? If so, I'm just about 1 1/2 hours from you. I'm in White Sulphur Springs, WV. Waynesboro is Gods country. Absolutely beautiful.