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Sending unit identification


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Alright guys, Aside from what the wiring harness tag would say, does anyone have any idea how to identify which tank the sending units go to? The catalog shows me that 18 gallon and 23.5 gallon sending units are the same but 16 gallon is different. Are there any physical characteristics about them that sets them apart?

 

 

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IIRC, the 16 gal tank is actually deeper than the 18 & 23 so the FSU is longer. I seem to recall finding pics and dimensions of a 16gal tank and it is more square. The 18 &23 are the same depth, hence the same FSU's, the 23 gal is just longer. Not sure if this helps...........

 

 

23gal FSU Dimensions.jpg

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Did some quick research, I got some info backwards I think. The 16 gal tank is long and shallow, so the FSU from a 16gal would not work in a 23gal. The 18gal is the one that is short and deep with the FSU being interchangeable with the 23.5gal tank. To my eyes, the last one in your pics looks shorter, particularly after the bend down to the pickup. Maybe measure them compared to the pic I posted. 

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  • 3 weeks later...

Any other key identifiers? I only ask because they all measure the same and one has writing on it denoting from a 90 LWB but that doesnt help by much. Maybe an Ωhm test even though all Renix SU's are 0-88. Maybe I could plug them in and see which ones will read past full and at full. 

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HO sender units read 0 ohms full to 105 empty. Renix 85 Full to 0 empty. So they work exactly opposite. Also all HO fuel sending units were the same I believe 52017559. Except the Diesel. When I did the LS and swapped the HO Instrument cluster so I could use a 120mph Speedometer I had to use a Pre 91 fuel gauge or it read wrong.

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I can’t imagine the three I have are HO but to be fair, whom I got them from couldn’t remember because he pulled them sooo long ago so I’ll check the ohms. I compared them all to a NOS 23gal SU I had and they all still looked them same in terms of angle and length so I’m not exactly sure. I don’t want to hang on to these if someone needs one but I also don’t want to sell the wrong one to someone. 

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1 hour ago, saveevryjp1998 said:

If it's factory straight piped, no doubt for sure it's an 86 or older, that I know. I still have a dozen or 2 senders yet. I've pulled over a hundred I think lol. You use to be able to order tank strap kits for lwb Mj at the zone for less than swb. I always ordered lwb kits for short and saved the extra strap since they are all identical. Short only has 2 is the difference. 

Neat! I figured it was 86 as it looked different than what I have normally seen and the only PN on it is on the wiring harness as a tag and it says  23.5gal on it. Thats good info to know. Hopefully I will find out the difference and be able to sell the three units as I don't want to hoard them when someone can use them. 

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On 1/10/2021 at 7:27 PM, eaglescout526 said:

I can’t imagine the three I have are HO but to be fair, whom I got them from couldn’t remember because he pulled them sooo long ago so I’ll check the ohms. I compared them all to a NOS 23gal SU I had and they all still looked them same in terms of angle and length so I’m not exactly sure. I don’t want to hang on to these if someone needs one but I also don’t want to sell the wrong one to someone. 

An ohm meter on the sender unit is the easiest way to tell if they are HO or not

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  • 2 months later...

SOLVED!!

 

IMG_8484.jpg.24595d2dc3a5b39c37916825fb139ca5.jpg

 

16 gallons have a short lever arm! Thats why the gauge can go past full! So 18 and 23 share the same sending unit according to the catalog which means I can now sell those three sending units!

 

Look at that arm! Its like a babys arm compared to the ones I have.

 

 

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1 minute ago, jdog said:

the hammer looks smaller

Thats the fathers garage special lol. That hammer has actually proven mighty useful for its stature. What happened was many years ago, my dad was using it and the head fell off and the wood split. So he cut it down and whittled it to fit the head. 

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10 minutes ago, eaglescout526 said:

Thats the fathers garage special lol. That hammer has actually proven mighty useful for its stature. What happened was many years ago, my dad was using it and the head fell off and the wood split. So he cut it down and whittled it to fit the head. 

ah, those are some of the better hammers

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