Bad fuel tank sending unit.....AGAIN!!

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tkelley72

Well-known member
Joined
Feb 1, 2013
Messages
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Location
United States
My Car
72 mustang convertible
In need of some expert input on this please. Once again I have a sending unit issue. I had the OEM unit replaced back in Sept. with a Doorman unit. It worked fine until the last week or so. I suspect that its the damn float again. I first suspected an issue a couple of weeks ago. I knew I had approx. a full tank, but when I took the car out it showed about 3/4 full. I dismissed it and assumed it was just an inaccuracy issue with the sender. I only drove it a bout 10 miles and put it away. The next weekend I got in for a short drive and noticed the gage showed a little over a half. Suspicions began to rise. This weekend I started it up and it showed to be about 1/4 tank. I let the car warm up about 5 minutes, got in for a drive and the tank was/is on empty!
I have done all the suggested tests. I have pulsating voltage at the sender. Gage goes to full when grounded out. The gage needle will move off of past empty about the width of the gage hash mark when I turn the key to the on position. All indications are to me that the float has a leak but wanted to get some opinions in case there is something I am not thinking of. I did see a new float product on line but from what I am told by the parts guy its basically a common float that has been dipped into a foam material. The attachment area is still exposed brass. May be less likely to sink but who knows. I attached a copy of it.
Would appreciate any input you guys could provide. Additionally, I still have the OEM sender (minus the rotted out float) that I could put back in if the Doorman sender could be suspect. Should I go back to that one just in case once I get a new float to eliminate the possibility of a defective sending unit. I checked it out with an OHM meter and it looks to read consistent throughout the range from 8 OHMs-78 OHMs.

Thanks guys
 

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  • float.pdf
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That's curious you had a problem with the Dorman unit. I assume it was the 692232. I have had that one in my car since 2017 and no issues so far. The only thing I see is when full, the needle fluctuates slightly, sometime more than full, other time just below. However, I typically refill when it hits 3/4 because I know it should take 19 litres (5 US gallons) and not break the bank.
Floats are definitely the weak point on these. Nothing is made like it used to be.
 
It is the Dorman 692232 unit. Does anyone have any comments on where to get a good quality float. I paid to have the unit installed and don't want to be out another $250 6 months from now. I know I could do it myself, however for health reasons I am physically unable to do do the job.
 
It is the Dorman 692232 unit. Does anyone have any comments on where to get a good quality float. I paid to have the unit installed and don't want to be out another $250 6 months from now. I know I could do it myself, however for health reasons I am physically unable to do do the job.
Sorry to hear about this especially as I've sort of promoted this unit.
Changing the float or complete unit is not very hard, but do it when the tank is near empty. Just be safe and use jack stands under the frame and axle. Lift left side only. Jacking the car would probably take longer than pulling the sender unit and fixing it. Of course this needs to be within ones mechanical ability, but it really is quite simple.
Now I'm also looking for a better float....... just in case.
 
I contacted "Desert Classic Parts" yesterday (they do restorations on these units) and he told me he only uses floats from "All Classic Parts" for his restorations and has very good luck with them. Only a couple of failures over the last couple of years. I'm going to call ACP today and talk to them. The price for the float is $10.00. Looks exactly like all the others but hopefully the actual quality is better....who knows? The guy at DCP was very helpful and informative. Sounds like the typical problem with ethanol in the gas. Creates a chemical reaction with brass and solder over time and deteriorates those materials. I've heard that the plastic floats don't hold up much better? Guess it's just a crap shoot these days. Thank you though for responding. I appreciate your input.
 
Hey there Terry! Sorry to see you're having trouble with this. Hope you're able to get a long term fix so you don't have to deal with this again.

Best Regards,
Brian
 
If you have not yet done so, I recommend getting the "special" fuel tank sending unit retaining ring wrench. I have used, in my distant past, a hammer and punch to get the retaining rind on and on. But, soon after I purchased the proper wrench, and now removing & Installing the retaining ring is a job made simple. There are a lot of places that sell the wrench. I purchased:

https://www.cjponyparts.com/cj-clas...v7ozM122Axw-iqcZZ842gtuJMDmmgu0V3asB4fnuBBP96
 
Hey there Terry! Sorry to see you're having trouble with this. Hope you're able to get a long term fix so you don't have to deal with this again.

Best Regards,
Brian
Thanks Brian. That sending unit is the gift that keeps on giving! I didn't expect the float to last forever, but 9 months... Come on! The last one lasted 20 years. Hopefully the one from "All Classic Products" is of better quality.
Good to hear from you buddy...
 
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