Hi All,
I've been working predominantly offline (PM) with Jim ( @Downey ) on gathering information and parts and am now int the process of starting to set this up on my '78 40.
I wanted to share the stock gauge between the two tanks and have a Pollak 6-port and a Centroid Sender that is rated at E120/F17 ohms.
I bought the Centroid Sender from Centroid and asked for it to be 11.5" long. Once I received it and saw that it will require 1.25" of clearance from the bottom of my tub, I cut it down to 8", so that it will mount in the trough on top of my tank:
I realize that that will mean my aux tank will register on the gauge as 'full' for 3.5 additional inches of gas - about 5-7gals of a 22gal tank. Not a problem. The white X is where I was going to mount it - I'm now mounting it to the right of the white X, in the trough.
However, when I tried to perform the "manual empty" calibration, from Centroid, I ran into problems. The stock gauge doesn't respond as Centroid expected.
I have performed various tests, requested by Joel at Centroid, and he's becoming convinced that I don't have an E120/F17 fuel gauge.
I've compared my fuel gauge to the 1978 version in Rudi's ( @bj40green ) excellent gauges and speedo thread and it looks like a 1978 FJ40 gauge to me.
The sender on the main tank sure appears to be an FJ40 sender (it even says FJ40 on top)
Before I give up and install a second gauge...
My main tank is 5/8-3/4 full right now and the ohms from the main tank sender measure right at 65ohms - I know 1/2 full is supposed to be around 49ohms, so 65 sounds realistic to me. Edit: I think I'm looking at this backwards... maybe 65ohms is too high for 5/8-3/4 full...
I have cut the YR sender wire, behind the fuel gauge, so I can wire the Pollak and DPDT switch. When I read voltage on the piece of YR wire that feeds into the gauge, I read 11.89V initially, then it jumps all over the place.
Does anyone know if this erratic voltage means that the stock gauge pulses a signal to the sender, or that the supply to the gauge has a mechanical regulator which pulses 12 volts to the gauge as a means of making an old-fashioned average voltage of say 5 volts?
These questions are Centroid's, not mine... but, I'd like to know nonetheless.
Also, I see that MUDders like @bsevans has gone before me with this Aux-Tank-Sharing-Stock-Gauge journey... has anyone encountered an issue with using an E120/F17ohm sender for their aux tank?
Thanks!
I've been working predominantly offline (PM) with Jim ( @Downey ) on gathering information and parts and am now int the process of starting to set this up on my '78 40.
I wanted to share the stock gauge between the two tanks and have a Pollak 6-port and a Centroid Sender that is rated at E120/F17 ohms.
I bought the Centroid Sender from Centroid and asked for it to be 11.5" long. Once I received it and saw that it will require 1.25" of clearance from the bottom of my tub, I cut it down to 8", so that it will mount in the trough on top of my tank:
I realize that that will mean my aux tank will register on the gauge as 'full' for 3.5 additional inches of gas - about 5-7gals of a 22gal tank. Not a problem. The white X is where I was going to mount it - I'm now mounting it to the right of the white X, in the trough.
However, when I tried to perform the "manual empty" calibration, from Centroid, I ran into problems. The stock gauge doesn't respond as Centroid expected.
I have performed various tests, requested by Joel at Centroid, and he's becoming convinced that I don't have an E120/F17 fuel gauge.
I've compared my fuel gauge to the 1978 version in Rudi's ( @bj40green ) excellent gauges and speedo thread and it looks like a 1978 FJ40 gauge to me.
The sender on the main tank sure appears to be an FJ40 sender (it even says FJ40 on top)
Before I give up and install a second gauge...
My main tank is 5/8-3/4 full right now and the ohms from the main tank sender measure right at 65ohms - I know 1/2 full is supposed to be around 49ohms, so 65 sounds realistic to me. Edit: I think I'm looking at this backwards... maybe 65ohms is too high for 5/8-3/4 full...
I have cut the YR sender wire, behind the fuel gauge, so I can wire the Pollak and DPDT switch. When I read voltage on the piece of YR wire that feeds into the gauge, I read 11.89V initially, then it jumps all over the place.
Does anyone know if this erratic voltage means that the stock gauge pulses a signal to the sender, or that the supply to the gauge has a mechanical regulator which pulses 12 volts to the gauge as a means of making an old-fashioned average voltage of say 5 volts?
These questions are Centroid's, not mine... but, I'd like to know nonetheless.
Also, I see that MUDders like @bsevans has gone before me with this Aux-Tank-Sharing-Stock-Gauge journey... has anyone encountered an issue with using an E120/F17ohm sender for their aux tank?
Thanks!
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