Messing with Fuel Tank Sending units again

One thing I want to get "fixed" on my Bullnose before the show is my fuel gauge.

Per a prior thread, it seems the spectra OE unit I have is the best I can get curently.

Since my post in that thread, the issue's gotten worse... mainly, I installed a Dennis Carpenter voltage regulator and now I rarely if ever see a full tank on fill up. I hit the E line at 1/2 a tank or so. Still drops faster the higher in the range it is.

My plan is to run the tank down and drop it (or tilt the bed, I've done it both ways) so I can remove and test the sending unit and do some testing. I'm wondering if maybe I can at least correct the range either mechanically (bend the arm) or electrically (add series/parallel resistors).

If there is a known good source that's currently in business (and not backlogged severely), I'd swap the unit again. Just something to help ensure I don't run out of gas driving to Oklahoma while allowing me to not stop for gas every 120 miles short of an emergency gas can.

I guess I was lucky with the 2 new senders I installed when rebuilding my truck.

Now what I did do before putting any gas in either tank was to turn on the key to see where the needles sat with nothing in the tanks.
That was just below the empty line.

I then added 5 gallons of gas to each tank and did the same thing, key on to see where the needles sat.
That was just on the empty line. So I know when the needle is on the line with either tank I still have 5 gallons left in the tanks.

I then filled both tanks and check where the needles sat. They are just above the full line when both tanks are full. I really dont care where the needles are when full, some dont like it above the full line.
I have never ran out of gas with the needles over the full line LOL.

Now it will take a little time for the needles to drop to the full line or a little below them but once it hits a certain point it dose drop pretty fast for both tanks but again I know when the needles hit the empty line I have 5 gallons left in the tanks.
I may run the first tank down to the line but I dont run the 2nd tank down that low just in case I cant get to a station to fill up so I dont run out of gas.

You may want to carry a gallon or 2 of gas and run the tank dry and put in just enough to get back to the garage to check the sender. This way you will know just how much fuel you have in the tank and where the needle should be, like just below the line or on the line.

Oh I did have 1 of the new senders float take on fuel shortly after the    truck was on the road.
I was able to snake the sender out by dropping the tank a little and swapping the floats from 1 of my old senders.
Dave ----

I'm having trouble with my new sender too. Got it from JBG. Guess it was bad straight out of the box. I'm going to have to drop the tank and pull the whole hanger. Ugh. Is there a brand that is known to be most reliable? I have a Carter unit that I could use if I can trust it.

I now know to test the sender before installing in the tank (experience is what you get when you don't get what you want), so I don't plan on putting in another non-working unit, but I don't want to get a cruddy one that fails quickly either...

I dont have a clue who made mine, plain white boxes w/PN only.
I have had them for long time but only used little more than 2 years and other than the float no issues.

I want to say I got mine through A1Auto on the web.
They were the only ones that had a 16 gallon side tank sender at the time so I got the rear 19 gallon sender from them at the same time.
Dave ----

I just did both my sending units.  I bought them from LMC, made sure the range of motion was the same as what I was replacing.

I put whatever gas I drained from the tanks back into the tanks (~5 gal each) and the needle sits on E for both.  I haven't filled the tanks since the truck isn't on the road, but I sure hope they read full.

don't be surprised if they read just under the full line. it happens a lot

Dropped the tank tonight.

Spectra OE sucks! The darn fuel sock wasn't even attached... and the rubber gasket for the electrical connection is already dry rotted pretty bad. 2 years old...



That fuel sock isn't coming out... After playing coathanger foosball with it for 30 minutes, I'm done. The tank isn't as empty as I thought and as a result I don't want to bother with disconnecting the filler neck at the tank and sliding the tank from under the truck. However, my fear is that sock will jam the next sending unit and I'll run outta gas. Maybe the filler neck hole has enough diameter to allow my long needlenose pliers to open wide enough to grab it? The sending unit hole was too small


Couldn't get reliable resistance readings... my good meter is at work, I'll bring it home for the weekend to retest. The metal/carbon track doesn't look too good. at no time did I get a passing reading (but with dull probes and low resistances that may be my meter and probes being junk).

Question: Are any of these any good?

https://shop.broncograveyard.com/1980-1984-Ford-F-Series-Truck-19-Gallon-Side-Tank-Sending-Unit/productinfo/30387/

https://www.dennis-carpenter.com/trucks/fuel-system/gas-tank-sending-unit/e0tz-9275-gx-gas-tank-sending-unit

https://www.npdlink.com/product/sending-unit-fuel-level/207582/60367

Looks like the Chinese one that didn't work for me... but maybe this is a better quality reproduction that also happens to use yellow wire?

A big pair of alligator forceps?
I have a few pair from back when my dad worked at Cavitron that are like 16" long.

I'm sorry Larry. 😖
It's so frustrating when new isn't good, or even functional.

I don't have enough experience to say who offers a good sending unit these days.
Maybe this is a good question for Mat?

I just bought a front gas tank level sensor pick up assembly from LMC truck.  I installed it and it is accurate and fit flawlessly.   The Spectra stuff was total garbage!  I went and had my local auto parts store pull one of those Spectra units to have a look, it was crap!  I will say, however, LMC truck's customer service is not the best!  The people who pick up the phone really do not know much about their products, but the stuff I have gotten from them is good!  

Personally I haven't had great luck with any LMC products. Armrests with self-stripping screws. Ranger sill plates that don't line up to stock hole patterns. With a somewhat recent change, I have hope they'll improve, but right now they're not my first choice for parts.

The JBG unit that I bought was worthless straight out of the box. That was the 84 Bronco sender. Be warned.

I'm with Jim - I don't have enough experience to really say.  But my two Spectra fuel delivery modules appear to be working fine - knock on wood.

Anyway, sorry you are having these problems.  

Ah, that's what JBG means...

I may try the NPD one... but they all look like the same part made in the same Chinese factory.

I have a tool that is basically a flexible wand about 2 feet long, it has a button on one end, and 3 fingers on the other. It's spring loaded to keep the fingers in and drawn together, but when you push the button, they come out and expand. It's great for stuff like this. Something like this.

https://www.amazon.com/Flexible-Grabber-Bendable-Reaching-35-4inch/dp/B07Y75N3DW/ref=sr_1_22?crid=1CPO24J5CT77X&keywords=grabber+tool&qid=1660317835&sprefix=grabber+tool%2Caps%2C166&sr=8-22

My two Spectra ones work fine, although the first front one was bad out of the box 10 years ago. No problem, new one was on it's way before I even removed the bad one. Send it back, no, just pitch it. It did help that the warehouse manager was my son.

NPD unit came in... passed bench testing. A few views:





Made in Taiwan... which I'll happily take over the PRC any day!



After some luck, cussing, and help from my wife (as a 3rd hand), using one the grabber tools suggested above, I was able fish the fuel sock out of the tank. It just slides on the pickup tune really loose. If it was glued, the glue must have dissolved. All the old parts:



If you're pulling an old spectra unit, beware. I'd like to hope it was held in by the bottom of the tank and only fell off when I pulled it.

Bench test wise, both units are reading 11Ω-12Ω at full swing and around 74Ω empty. In the middle, the new unit reads around 33Ω; I'm getting 47Ω on the old one. The new unit isn't fully hitting the E line; manually forcing the arm to full gets it almost to full:



(my wife took those while I was under the truck moving the arm).

Mid-range it was around 3/8-1/2... No pic though.

I did close up the connector contacts while I was down there (after the pics were shot) which may change the results if there was a sketchy connection.

With what's in the tank now, it's reading just under 1/4. Will need to do some testing to see... it might be better? At least I have fuel sock (pre-filter) that's firmly attached!

ratdude747 wrote

NPD unit came in... passed bench testing. A few views:





Made in Taiwan... which I'll happily take over the PRC any day!



After some luck, cussing, and help from my wife (as a 3rd hand), using one the grabber tools suggested above, I was able fish the fuel sock out of the tank. It just slides on the pickup tune really loose. If it was glued, the glue must have dissolved. All the old parts:



If you're pulling an old spectra unit, beware. I'd like to hope it was held in by the bottom of the tank and only fell off when I pulled it.

Bench test wise, both units are reading 11Ω-12Ω at full swing and around 74Ω empty. In the middle, the new unit reads around 33Ω; I'm getting 47Ω on the old one. The new unit isn't fully hitting the E line; manually forcing the arm to full gets it almost to full:



(my wife took those while I was under the truck moving the arm).

Mid-range it was around 3/8-1/2... No pic though.

I did close up the connector contacts while I was down there (after the pics were shot) which may change the results if there was a sketchy connection.

With what's in the tank now, it's reading just under 1/4. Will need to do some testing to see... it might be better? At least I have fuel sock (pre-filter) that's firmly attached!

Replacing my tank is on my list of after restoring the major things that need attention, so this post was helpful to me.  I may even add a second tank.  I definitely need to solve the spare tire issue--do not have one, and there's no mounts for under the back of the truck--where the 2nd tank goes.  

Love the PRC comment.  I have had a lot of luck with Taiwan parts, and (for the Harley) parts made in Japan.

Thanks for posting this.  Helpful!

Larry - If you haven't you can replace the ICVR with an adjustable voltage regulator and run the output voltage up slightly to get it to show Full when the tank is full.  Of course the oil pressure and coolant temp readings will come up as well, but there's nothing very precise about them.

I have a Dennis Carpenter ICVR installed... it made the gauges slower and the fuel gauge not read as high (on the old sending unit). Honestly, as long as I have a gauge that can tell the difference between 1/2 a tank and 1/4 a tank I'll be happy enough... so far, it is. It hasn't been driven... just going off what the gauge reports at the current fuel level, which is an improvement!

Funny enough with a full tank and the engine running it is getting all the way to the full line. I guess the Dennis carpenter regulators aren't particularly precise either . I'd think they'd use an LDO or a buck converter... heck, even a zener diode and some transistors would be better than this???

(No, I'm not going to open mine up and see what they put in there... I'll design a custom piece if I get that mad at it...)

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Haven't run a full tank cycle yet, but between a topoff and a fillup so far it's working a *lot* better than before. Drops to just above 3/4 somewhat quick, but seems to drop at a more reasonable rate from there.