Fuel Sender dramas

[Sam Burton]

Afternoon all,

Very close to being back to fully working after months of rewiring.

My 2x last electrical gremlins are Rev counter not working (i think my new gauge is faulty, but may need further assistance if not)

But the biggest issue is my fuel gauge is like a wind sock, it's never steady on any reading, ive taken it out and cleaned it up and reset the contact arm, but made sod all difference, installed a new fuel gauge as thought it was that. Now i think it's the actual sender unit.

 

Can any advise what sender this is, as cannot see any part numbers on it, i believe it's a Robin Hood stainless fuel tank as it's pretty small 

 

Thanks all

[IanS]

First your problem is probably not having a damped guage rather than the sender. As you drive the fuel sloshes about and a fast acting guage jumps all over the place as the float moves with the waves.

The sender to me looks like a modified sierra sender. The sierra one has a 3 pin socket and an earth tag, this appears to have been replaced with a single connection.

The 3 connections were 2 variable connections 1 to the guage and the other to the optional MPG computer fitted to top spec cars, the 3rd contact was a simple on/off to a low fuel light.

Robin Hood fuel tank is rectangular stainless and fitted across the back of the car and could hold just about 30 liters not all useable as he flat bottom leaves several liters sloshing round after the pickup sucks air. Also the sierra unmodified filler neck sticks quite a way into the tank and if no provision for the air getting out has been provided this prevents the tank beeing fiilled to the brim. The second pipe is intended as a fuel return not a vent.

 

I hope that this helps.

Edited March 17 by IanS
spelling

[LeicJim3a]

IanS very insightful as always, I too have the same issues as well as reading full when empty and empty when full ! You mention "dampened gauge" I have done some research after reading this as it was a new term to me and it is becoming apparent that putting a capacitor in the wire from sender to gauge makes it less reactive meaning fuel sloshing is less noticeable on the gauge reading,  but this opens up even more queries ! 1) what capacitor is right ? is there a simple wiring diagram/method ? any ideas on gauge reading in reverse I presume 2 wires the wrong way round on back of gauge but which 2 ? 

[IanS]

Back in the day.. Fuel guages were a hot wire movement where the electric current heated a wire in the guage which warmed it up and thus it got longer which was used to move the needle. It takes time to warm the wire so the gauge is said to be damped. You would switch the ignition on and the needle would creep up over a couple of seconds.

Now guages are moving coil and react very quickly.

Guage reading full when empty and empty when full is down to the sender in the tank and idealy should be fixed there.

Modern cars drive the guage as a stepper motor system with all the damping done is software in the ECU.

If you want to try a capacitor then https://cpc.farnell.com/panasonic/eeufm1v102/capacitor-radial-1000uf-35v/dp/CA07431 might work, I have not tried this myself, connect the negative contact to ground and the positive to the wire from the sender to the guage. This can be done on the back of the guage.

[phaeton]

https://spiyda.com/fuel-gauge-wizard-mk3.html

Might be a solution for you, it's a little while since I had anything to do with Chris's products but they were always first class along with brilliant support.