[glenry]

i fitted a 2nd fuel tank ages ago to my TD42 and wired both tanks to the standard fuel gauge and use a switch and pollak valve to flick between the 2 tanks. I found the sub tank reasonably accurate but the main tank very inaccurate due to the extra resistance from extended wires.

purchased a vdo fuel level guage and was told it will work on 1 of 2 fuel senders.(50/50 chance of had the right one). Of course i had to have the wrong one and sub gauge is useless.

does anyone know the resistance of the GQ fuel guages? at empty, half and full?
the tank is a LRA and as far i know uses the same standard GQ sender and is the same as the auxillary tank used in the petrol/gas conversions.

can i please have the width of the sender plate that seals at the tank also? (6 bolt)

alternatively im open to suggestions and which other a/m gauges will be compatible with standard sender.

It appears the other sender will not fit my tank.

anyone know if i can buy the vdo sender and swap the electronics/float etc?

Thanks

 

[GeeCee]

If you have an LRA tank, they are (at least were) designed for, and came with a standard OEM fuel sender.

Switching between the two to the standard dash indicator should be no problem.
Not sure what your problem is with extended wires.

Full = 4.3 to 5.7 ohm
Empty = 74.3 to 84.8 ohm

 

[glenry]

GeeCee thanks for your reply.

This may seem obvious but what is OEM? did you mean OHM's?

when using the main fuel gauge, i would do about 250km from full to empty, fuel needle would then go approx 5mm below empty, stay there for another 100kms, then slowly rise up to 1/4 and then slowly go back down between 1/4 and empty and i'd run out of fuel. basically i had very little idea when i was about to run out of fuel. I believe cutting the main fuel sender wire and joining wires to run them to the pollak valve caused the issue, as longer wires increase resistance and therefore changing the fuel accuracy.

possible if they were closer it would of been better

thanks for the help with ohms, do you know the size of the sender by any chance?

 

[GeeCee]

Original Equipment Manufacturer - in this case a genuine Nissan supplied part.

Just googled what a Pollak Valve is.
Was the main gauge OK before installing this valve - maybe the valve is faulty.
Maybe it's just a coincidence and your main fuel sender is faulty.

Aditional resistance would not make the reading erratic which you seem to have observed, it would just offset (lower) the true reading by a fixed amount throughout the range.

I suggest you connect the main tank sender wire directly to the gauge wire at the Pollak Valve. This will eliminate the valve from the problem, but keep the additional wiring.