Fuel sending unit replacement for an accurate reading

[Meanmyz]

Originally Posted by 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

Yep, I can see how that could happen from your explanation. And agree on your fix (KISS). That is probably how it got goofed up in the first place...that a service tech bent it. I know from the Carfax that it was at the dealer for a no start after it sat for a couple of years.

I haven't myself ever worked on a fuel sender, so I am learning.

[Flyman 27]

I was told by a very reliable source (-=Jef=-) that the sender unit is the same as a standard C4. So you could find a deal on a standard C4 complete unit & swap the sending unit. That would be the least expensive way to get a new sending unit.

[jss06c6]

I've not heard of a "bladder" in the fuel tank, but here is a tray that lies directly below the sending unit arm and float. There is a chance that your float arm somehow got bent to the side slightly during installation. This would cause the float to hang up on the lip of the float tray. I would expect, however, that this would cause you to show fuel still in the tank, when in reality, the tank is nearly empty.[ATTACH]

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[Paul Workman]

Originally Posted by Demps

Bend the arm of the float.

Ted

I wuz going to say that too!

Meanmyz, just to add: bend the arm toward the bottom of the tank, moving the float down equiv to about 3 gallons worth.

[Meanmyz]

Originally Posted by Flyman 27

I was told by a very reliable source (-=Jef=-) that the sender unit is the same as a standard C4. So you could find a deal on a standard C4 complete unit & swap the sending unit. That would be the least expensive way to get a new sending unit.

Thanks for the replies. And this is good to know. I believe this because it is the same tank as other C4's. It is just the piggy backing hardware and extra pump, which I already have.

[Meanmyz]

Originally Posted by Paul Workman

I wuz going to say that too!

Meanmyz, just to add: bend the arm toward the bottom of the tank, moving the float down equiv to about 3 gallons worth.

Thanks Paul. I think I will look to see what I have in the tank and current condition before ordering and maybe just do this.

Depending on condition, I wonder if there would be benefits of a new sock and pumps on a 60k+ mile car that has had another 100 HP added to it with Marc's 510/350 package.

[Marc Haibeck]

I have been cleaning the fuel level sensor as a repair procedure for quite a while. Recently I have encountered two units that would not stop skipping resistance at less than 20 ohms. That's about 3 to 0 bars on the gauge. This can cause the nasty jump from 3 to 0 bars in just a few miles.

I'm using a Stewart Warner universal fit sensor and fabricating an attachment to ZR-1 sender assembly. It's a modern thick film design. I get them from Summit Racing. Number SWW-439363-D. $37.

[carter200]

This is also a good time to think about changing out the plastic “y” for the billet replacement unit I machine. It will not break nor leak like the discontinued plastic one will. If interested contact me via email. Thanks for looking.

[conesare2seconds]

Marc, thanks for your post and finding a solution. Also, Jssc06c6 is almost certainly describing the cause of my old car’s behavior. The myth of the tank bladder: busted.

[Jagdpanzer]

Thank you Marc for sharing this information. I was also thinking about going the same route. Looks like a reasonable cost solution that solves another parts availability problem. Time to dig out that spare ZR-1 gas tank pump/sending unit assembly I’ve been holding on to for years with a defective level sensor.


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