Fuel sending unit replacement for an accurate reading

[Meanmyz]

Hi guys. I have a fuel gauge that has read inaccurately since I purchased the car in 2012 ('95 Z).

My question is, can you buy a new fuel sending unit without buying the fuel pumps?

So far my research as found that the GM part number is 19180770. OEM units appear to retail for about $370. I have to guess that this price includes pumps???

It will be a winter project for me to fix this. The problem I am having is that after filling the tank full, it doesn't take but a few miles to immediately lose the first bar on the gauge. After that, my fuel gauge goes down faster than the actual fuel level of the tank. By the time my gauge reads empty, I will find that I still have about 5 or 6 gallons in the tank.

Sure, I can continue to drive knowing that I have fuel, but then my "check gauges" light is on because according to my fuel gauge, I should have been walking already!

When I had Marc do my engine package for the car in 2014, I had him take a look at the sending unit. He looked it over for problems, with nothing apparent, but the problem persists.

This car has been a fun project for me with the goal of making it "awesome" when I get done. I do plan on keeping it. I add these statements in helping you assess my plan of action for repair. Thanks!

[BigJohn]

Yep that’s how it was set up at the factory

My gas gauge is the same as yours

It is to keep you from starving the fuel pumps

[Meanmyz]

Originally Posted by BigJohn

Yep that’s how it was set up at the factory

My gas gauge is the same as yours

It is to keep you from starving the fuel pumps

Yes, but I shouldn't have that much gas in the tank when it says I am empty. I have two low mileage Z's and two more C4's to point out that this is the one with the problem!

Edit - John, 5-6 gallons is a guess, because I couldn't remember. I think it is usually more. I agree there should be fuel in the tank to not starve a pump and to keep it cool.

[Meanmyz]

I apologize if this appears to be a dumb question.

Can you buy an LT5 fuel sending unit separate from the pumps?

[Demps]

Bend the arm of the float.

Ted

[Flyman 27]

You can buy the sending unit without the pumps, search around the net. I can't remembered where I ordered from.
I was told that the few gallons in the bottom of the tank prevents the fuel pumps from overheating.
When my gage says empty &n shifts in to reserve mode, I still have 4 gallons left. I was told that this was correct.

[Jagdpanzer]

I’ve been looking for the same thing for years and so far have not found one as a separate replacement part. There are outfits that specialize in rebuilding old fuel tank level senders. The couple I’ve inquired with rewind the resistance strip by hand and charge $100+. Our senders are the same standard GM 90 ohm swing-arm potentiometer used on many other GM car models from 1960s to 1990s. Strange it’s not available as replacement part.


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[Meanmyz]

Thank you guys for your answers.

Phil, your answer tells me that no, you will not find a GM part without pumps and really gives the answer I am looking for.

Flyman, I am guessing these are aftermarket, and while they may be quality, I will look and do some more research.

Bending the float is easy, but also hit and miss. What would have bent it out of place in the first place? I would save the money and do that on my daily driver, not this car, and I am guessing you would feel the same way.

Thanks guys.

[conesare2seconds]

Funny enough, I’ve always had the opposite issue with my C4s - flat out of gas with bars still showing on the gauge. And the first 1/2-tank goes down slowly while the indicator races toward empty below half a tank indicated. I think there is a plastic bladder in the tank that can collapse over time and interfere with the sending unit. You have a good problem, I think.

[Demps]

So...I know a guy that...

When you put the sender [back] in the float can hang up. First, while getting it all in through the tank opening. Second, once in the tank IF one were to reach in to position the assembly it is possible to push against the float arm.

All of this is assuming the range of measurement is there. There are some posts here or CF (check Cliff's solutions) on how to measure resistance. I'm also a K.I.S.S. follower, & would slightly bend it (float) up if the sender has been removed lately.

Ted