Auxillary Fuel Gauge?

[Skillet]

Auxiliary Fuel Gauge?

Just installed a 44 gallon long range fuel tank which utilizes the Toyota auxiliary tank sending unit.

I am not so hot on the idea of tapping into the existing fuel gauge and toggling back and forth so I am looking for a decent aftermarket fuel gauge that would work with this stock Toyota sending unit.

I am thinking that a digital gauge would look pretty slick especially if it is low profile. Just something for general, quick reference.

Anyone know of anything like this that would work well?

 

[pappy]

I'm not aware of an aftermarket gauge that will work with the Toyota sending unit, or a sending unit that willw ork with the Toyota gauge. You can get a gauge/sending unit from Autometer. It should not be too hard to adapt the tank to the Autometer sending unit.

 

[Skillet]

I am not very familiar with the whole gauge / sending unit thing, but I do know that the sending unit is already purchased and installed in the tank, not going anywhere so whatever gauge I use, will have to work with that unit.
Don't they all pretty much work the same way?

There are three wires on the sending unit:

White w/ black = ground
Yellow w/ red = gauge
Yellow w/ black = shut off (Scolero switch)

Pretty simple.

 

[ParadiseCruiser]

Jeb -

The principle of the Toyota fuel level sender is to place a variable voltage across the fuel gauge based upon a resistence created from a wiper that slides across a winding on the sender, depending upon the level of fuel in the tank.

The gauge needs to be calibrated to the voltage range of the sender in order for it to accurately read the level of fuel in the tank. No telling what an aftermarket guage is expecting to see in terms of that voltage, so there is no way tell how accurate it would be.

The good news - if you are referring to the Toyota OEM sender (either the primary sender, or subtank sender) - is that they are identical in terms of this measurement and will both give an accurate reading on the stock fuel gauge that is in the gauge cluster. This presumes of course, that the sender in your long range tank has its float calibrated to the level of fuel that is in there - the length of the float arm will be different for tanks deeper than the OEM subtank.

This is the reason why so many of us just tap into the existing gauge. The wiring is easily accessible behind the DS kick panel (same place where the CDL switch pin 7 mod is done).

Cheers, R -

 

[desertdude]

I have the same aux tank - and sender unit - I am hoping to use a cyberdyne fuel gauge I got from http://www.egauges.com - if it will not calibrate properly - I figure I will do the switch and OEM gauge - I also have Georges modules to control the fuel transfer pump to figure into the mix

Thanks also to Ron for posting your info

 

[Mike S]

My 80 has the switch over using the OEM in dash gauge, which is switched by a 3-way relay responding to the subtank toggle switch. If you are just transfering fuel to the front tank, it may not be very important - just run on the data from the front tank.

If it is important to you, I can send a wiring diagram that shows the parts and schematic for wiring the relay. Just PM me with a fax number.

Mike

 

[ParadiseCruiser]

Hey Mike !

Hmmm, that's an approach that I have not heard about. You do not need a relay to use a single gauge for both tanks, nor do you need to tie it to the subtank pump switch. Sounds unnecessarily complicated to me.

Any particular reason to have done it that way that you can think of?

Cheers, R -

 

[Mike S]

Hey Mike !

Hmmm, that's an approach that I have not heard about. You do not need a relay to use a single gauge for both tanks, nor do you need to tie it to the subtank pump switch. Sounds unnecessarily complicated to me.

Any particular reason to have done it that way that you can think of?

Cheers, R -

The relay simply switches the line inputs from the fuel level sender to the gauge when the tank is selected via the subtank switch. If you did not switch between the two, the input to the in-dash OEM gauge would be from BOTH tanks...so how do you know how much fuel you really have?

The PO had this installation done. There are two parallel fuel lines, and a 2 line in / single line out switched fuel valve that also works off the relay to switch inputs to the engine fuel system, It is much more usual to simply have a transfer pump to tranfer from the rear tank to the front tank.

The single advantage that you would get from this parallel set-up is in the event of a front tank fuel pump failure, you have a redundant parallel system to continue fuel delivery. It is more complicated, with additonal potential points of failure.

M

 

[ParadiseCruiser]

M -

Thanks for that.

>> There are two parallel fuel lines...

Yes, a redundant fuel system does have its advantages; in fact some Oz spec trucks (predominantly diesels, I believe) were set up that way.

>> If you did not switch between the two, the input to the in-dash OEM gauge would be from BOTH tanks...

Agreed. My point was why the relay was used, rather than a simple switch. I can see now that in your case, you want to see the level of the tank that is feeding the fuel rail. The use of a redundant fuel system is really a different application than a transfer pump... that was not immediately apparent (to me) from your first post.

I just wanted it to be clear - for the benefit of others - that a simple SPDT rocker switch will accomplish the same task in systems where a transfer pump is used and there is no need for the relay.

Cheers, R -

 

[hoser]

Anybody have experience with the Trax-II Fuel Monitoring System?

It monitors your main and aux tanks, transfers fuel automatically (keeps them at the same level) and has a monitoring system that tells you the total gallons, fuel economy, avg speed, avg fuel consumption rate, time/distance until fuel is empty, total cost of fuel and more.

They list calibration specs for the Tundra and Tacoma.