Any reason a fuel sender shouldn't touch the bottom of the tank?

I've been troubleshooting a fuel gauge issue the last couple days.

when I pulled the sending unit from the tank, I realize on it's lowest possible setting, it's still 3" from the bottom of the tank.

Any reason not to replace it with one that reaches the bottom?

No reason, but you'll have to get used to the new gauge lying to you.  There is a reason that your current gauge will go below E before you sputter and die.  If you put the float on the bottom, you'll get slosh/air/run out of fuel before the gauge reads E.

It's a built-in reserve.  As long as you're ok with re-learning your gauge, go for it.

I put a sender in a custom fuel cell I had built years ago.  The VDO instructions said to measure the depth of the tank and make it so the float is 1" off the bottom.  I'm sure that recommendation would vary widely  based on the style of tank.  This was an under-trunk flat tank, but I would imagine something like a long, rectangular tank like in a truck or van might have totally different needs.

With an old(er) tank, you run a risk of sucking up rust and crud.

In reply to Appleseed :

I could be wrong, but I think he's talking about the gauge sender as opposed to the pickup screen.

Appleseed said:

With an old(er) tank, you run a risk of sucking up rust and crud.

this is just a float in a boat (plastic tank).     Fuel pickup is elsewhere

I always read sender and think pick up. Derp.

In reply to Grtechguy :

If it's a portable tank (6 gal), do whatever you want.  If it's a permanent tank installed under the floor, my original advice applies.  Just be ready to relearn your gauge.  I'm just afraid it will normally drop to an indicated 1/8th of a tank and you'll start sucking air every time the fuel sloshes around.  YMMV

I have had a float stick to the bottom due to stale fuel/crud issues. I think the float should not go within a 1/4" of the bottom just to avoid the possibility.

Curtis73 (Forum Supporter) said:

In reply to Grtechguy :

If it's a portable tank (6 gal), do whatever you want.  If it's a permanent tank installed under the floor, my original advice applies.  Just be ready to relearn your gauge.  I'm just afraid it will normally drop to an indicated 1/8th of a tank and you'll start sucking air every time the fuel sloshes around.  YMMV

Good point.  this is 50G buried in the floor.