Fuel Sender

[marauder11]

Just looking at a new fuel sender. As i am looking at this i wondered. How does this safely work with 12 volt power going to the sender by the fuel? So i figured i would look dumb and ask. To me it seems like the power by the fuel is a bad thing. Can someone educate me on this.

Thanks

 

[Scott Danforth]

should only be a variable ground coming from the fuel sending unit to the gauge.

 

[marauder11]

I know there is two wires a ground and the power. I was more wonder the whole power by fuel and how that is safe. There are a lot of things in life i am willing to just say ok too. This one just got me thinking is all.

 

[alldodge]

I know there is two wires a ground and the power. I was more wonder the whole power by fuel and how that is safe. There are a lot of things in life i am willing to just say ok too. This one just got me thinking is all.

They are sealed units, only a single pin comes out which is attached to the variable resistor inside. They work on very little current and being sealed there is no issue. Similar items are like seal starter solenoids in the engine compartment. They also put electric fuel pumps inside fuel tanks on cars

 

[Chris1956]

A very small current (like .05A) runs thru the sender to ground. It is highly unlikely it could make a spark.

 

[smokeonthewater]

Power and fuel is a non issue.... Spark and fuel is a non issue.... Spark, fuel vapor, and oxygen..... Big issue.

The "hot" wire is the negative side of the gauge VERY little amperage comes through that wire. Not much chance of a spark...Still the connection should be secure so it doesn't come loose... The tank should be leak proof so the fuel doesn't come out and mix with air AND the compartment should be well ventilated to keep any fumes from building up anywhere near the lel (lower explosive limit) concentration.

 

[gm280]

If that scares you, don't even look in any vehicle fuel tank. The fuel pump and sender units are sitting in the gas at the bottom of the tank. But it will never ever explode because there is zero air to support combustion. Fuel senders use electricity through the variable carbon track to change the resistance to send to the gauge. And even if there were lots of amps flowing through, it will not ignite because there isn't enough air to support combustion. And it really is only the vapors that could ignite anyway, but only with a certain amount of quality air! I actually tested that myself when trying to make a reed type fuel sender unit. Gasoline does not allow electricity to flow through it. In other words gas is not a conductor. Water will conduct electricity very easily, but not gas...and that IS a fact! So relax and forget about fuel and electricity. Not a problem... If the fuel pump in a vehicle gas tank being submerged in gas with bushes and such won't ignite, there is zero change for a fuel sender unit igniting the gas... I know doesn't sound correct, but it is...

 

[marauder11]

Thanks guys it was just one of those WTF moments and i had never once really thought of it.

 

[Chris1956]

I need to disagree with the no air in a fuel tank remark made by some. When the fuel level in a tank gets low, air replaces it. So fuel tanks have an explosive fuel-air mixture in them most of the time. The good news is that the design of the fuel gauge sender does not spark.

Fuel pumps inside fuel tanks are cooled by the fuel, but no electricity is introduced to the fuel by the fuel pumps. They obviously need to be well sealed, to prevent a fire.

Fresh water is a poor conductor of electricity. Salt water is a bit better conductor, but still lousy compared to most solid metals (iron, nickel, copper, aluminum etc.)

 

[dingbat]

The wonders of epoxy encapsulation.....

 

[smokeonthewater]

No Title

Guess again... The yellow is fuel.

 

[gm280]

Guess again... The yellow is fuel.

Yes smoke you are most certainly correct! In normally every fuel pump tank install, ln the actual fuel pump, and that does mean brushes riding on an armature, is totally submerged in gasoline. So yes there is no epoxy sealed fuel pump in a modern tank pump setup. The fuel pump is sitting in the gas as it pumps fuel out of the tank... There is nothing there to separate the fuel from the brushes and armature. Believe me, I just change one a few months ago...so I know for positive...

 

[shrew]

They also put electric fuel pumps inside fuel tanks on cars

In fact, most people think the 'Low Fuel' light is to warn you that you are going to run out of gas. Actually, that is what the gage is for. The automotive fuel pump is frequently cooled by the fuel itself. The light is a warning that the pump is no longer being properly cooled and prompting you to fill the tank to avoid burning the pump out. Riding around with the low fuel light on can prematurely burn out the fuel pump.

At least that is how I understood.

 

[dingbat]

Guess again... The yellow is fuel.

how did we get from fuel sender to in-tank fuel pumps?

 

[smokeonthewater]

how did we get from fuel sender to in-tank fuel pumps?

Guess you'd have to read the thread.