Replaced Fuel Sender, Gauge off by 10 gallons now.

[Tom P]

So I recently replaced the fuel pump/sending unit in my K3500. I went with a Denso unit because I like their stuff and Its probably made better than the Delco one anyway. Unfortunately I think I may have made a mistake in doing so. Its not a dire issue by any means but it took my fuel gauge from having 5-6 gallons left in the tank on E to having over 10 gallons left in the tank on E. And I'm talking passed the red lines down in to the drawing of the empty tank. It is the correct unit for my truck (double checked that 4 times). I did fix the ground when I replaced the sending unit. The original ground was corroded beyond repair so I drilled a new hole, cleaned up the area with a wire wheel and added new terminal ends and new hardware. I wired in the new harness plug and used shrink wrap on all the connections. I checked for full motion of level indicator and all seemed ok.

Has anyone experienced this before? Thanks in advance

 

[Christian Steffen]

I assume you didn't accidentally bend the float or anything like that? Mine will occasionally throw erroneous readings too. I guess the silver lining is that its better to read less than actual, as opposed to the other way around lol

 

[Tom P]

I suppose that could be possible. This summer I plan on taking the bed off of it again for a while to clean up some rust issues. I'll pull the sender back out and double check.

 

[Tom P]

Mine will occasionally throw erroneous readings too.

So far its been rather consistently wrong... lol

 

[Christian Steffen]

So far its been rather consistently wrong... lol

I would think that would point more towards a float issue than anything. Pretty sure that contact pad by the float is just worn out on mine, so sometimes it must lose connection.

 

[bornchevy]

Iv had the same issue on my truck (34 gallon tank) since I bought it. Replaced the fuel pump when I thought the tank was empty. Ran the truck till the tank was empty, well when i went to drop the tank I was surprised at how heavy the tank was. Well to my surprise there was 10 gallons of gas left in the tank. Checked depth of the pickup with the tank depth and they were pretty damn close about 1/8" from the bottom of the tank. Put the new fuel pump assembly in and filled her up, ran her out of gas again and then filled it up and it only took 22 gallons, did this a few more times and it only ever takes 22 gallons to fill her up. My fuel gage is saying the trucks empty, the truck says its empty (wont even run at idle on level ground), but there is still 10 gallons left in the tank. Curious to see where this thread goes.

 

[Tom P]

Well I know the pump is sitting on the bottom of the tank because I had to compress the sending unit to get the snap ring in. I only have a 25 gallon tank. With the new unit, when the gauge reads empty the truck still has 8-10 gallons left in the tank. I have not run the truck dead empty yet though. When It gets close I'll probably grab a gas can and go for a drive until it pukes and then make a mark from there.

 

[someotherguy]

When it's full, does the needle go past the full mark? If so, just re-pin the needle. It's crazy easy to pop the lens off the cluster, just be careful you don't bump the hazard button with the dash bezel while you're removing/installing, since the hazard button is so damn fragile.

Anyway pop the needle off with a full tank and push it back in the correct place. Run it down to half, go fill up the truck, see if it takes around 12~12.5 gallons (half your 25 gallon capacity, of course) - then you can be pretty confident the "empty" mark will be close to accurate, as well. Though I'd still carry a gas can until you know for sure...

Richard

 

[Tom P]

When it's full, does the needle go past the full mark? If so, just re-pin the needle. It's crazy easy to pop the lens off the cluster, just be careful you don't bump the hazard button with the dash bezel while you're removing/installing, since the hazard button is so damn fragile.

Anyway pop the needle off with a full tank and push it back in the correct place. Run it down to half, go fill up the truck, see if it takes around 12~12.5 gallons (half your 25 gallon capacity, of course) - then you can be pretty confident the "empty" mark will be close to accurate, as well. Though I'd still carry a gas can until you know for sure...

Richard

Wow what a stupidly simple idea. Yes a full tank tanks it much higher than the full point. It seems to me that it’s falling faster than it should but I will definitely look into that idea.

 

[Christian Steffen]

Iv had the same issue on my truck (34 gallon tank) since I bought it. Replaced the fuel pump when I thought the tank was empty. Ran the truck till the tank was empty, well when i went to drop the tank I was surprised at how heavy the tank was. Well to my surprise there was 10 gallons of gas left in the tank. Checked depth of the pickup with the tank depth and they were pretty damn close about 1/8" from the bottom of the tank. Put the new fuel pump assembly in and filled her up, ran her out of gas again and then filled it up and it only took 22 gallons, did this a few more times and it only ever takes 22 gallons to fill her up. My fuel gage is saying the trucks empty, the truck says its empty (wont even run at idle on level ground), but there is still 10 gallons left in the tank. Curious to see where this thread goes.

That is strange that the 10 gallons is essentially useless. Is the tank aftermarket, or did it come from the factory with it?