As some of you might remember, I swapped my original fuel sending unit on my "78 280Z a few weeks ago. Although the original sender measured fuel level adequately, the "FUEL" warning light had stopped working a couple of years ago so I decided to spend some quality quarantine time swapping it for a new reproduction unit from Z Car Depot. I had already tested the yellow/blue lead and assured I had continuity from the "FUEL" light in the dash all the way back to the sender plug.

I plugged in the Z Car Depot sender to the harness before inserting it into the tank and upon turning the car key to the "ON" position the "FUEL" illuminated and I could change the position of the needle on the fuel gauge by moving the floater arm on the sender. Everything seemed to work as it should. Once I put the sender into the tank and locked it, the needle in the dash positioned itself to the right (I had an almost full tank of gas) and the "FUEL" warning light turned off (as it should). Needless to say I was very happy with the way everything went.

I drove the car for the first time since the sender swap about a week later and went on a nice 25 mile run. After driving for about 15 minutes the "FUEL" warning light came on! The tank was still pretty much full and the needle on the gauge was close to the extreme right. I drove another 15 minutes to get home and the "FUEL" light did not go off until I turned off the ignition. I turned the key back to the ON position to power the fuel gauge and the "FUEL" light did not illuminate BUT upon turning the key to START and running the engine the darn light came back on.

I performed the same routine a few days later and the malfunction remained exactly the same. "FUEL" light comes on after the car has been running for about 15 or 20 minutes. The tank being over half full. The "FUEL" light will turn off when I shut the engine it and will remain off even with the car key turned to "ON" with the fuel gauge working but will illuminate as soon as I start the car again. After the car sits overnight the light will be off until the engine runs for about 15 minutes and the whole "Groundhog Day" scenario repeats itself. In other words, the engine needs to be running for the malfunction to occur. Leaving the key in the "ON" position (which powers the fuel gauge) will not trigger the "FUEL" light. I'm totally stumped!!

I contacted Scott at Z Car Depot and he said he hadn't had that malfunction reported before and he immediately sent out another sender. Amazing customer service!!

I installed the "new" sender the day it arrived and the malfunction remained exactly the same. I made sure all the contacts on the plug were clean, applied dielectric grease, looked for anything that might look strange, successfully tested the sender by plugging it into the harness before putting it in the tank and nothing changed. I'm even more perplexed by the malfunction. As always, any help from the vast knowledge base will be greatly appreciated.

Keep safe everyone. 

Gotcha - it's just strange that we have to do that on a brand new part

I wrote ZCD a couple of weeks ago and described the issue along with our conclusions (after so much friggin work!), and the "easy fix" of using a different resistance bulb. They thanked me for being so thorough, that my email would be forwarded to the "boss", but they had sold many sending units without any issues. They left it at that, regrettably.

 

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Just now, dmorales-bello said:

I wrote ZCD a couple of weeks ago and described the issue, or conclusions (after so much friggin work!), and the "easy fix" of using a different resistance bulb. They thanked me for being so thorough, that my email would be forwarded to the "boss", but they had sold many sending units without any issues. They left it at that, regrettably.

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Right, they told me the same thing before they sent a replacement.  😕

This is one of those critical moments in running a business.  Do you take a relatively small loss, to keep your customers happy and your reputation in good standing.  Or do you hold your ground to save that small cost of fixing the problem, destroying the good will that exists and damaging future sales.  California Datsun comes to mind.  I hope these guys can handle the broad view.  They have a huge selection of parts now, the business has grown quite a bit since it first appeared, not that long ago.

This thread is like a case study in a business course.  What not to do.  Let's see what happens next...

https://zcardepot.com/

Edited September 28, 20204 yr by Zed Head
gerund is not ground