Low fuel warning system failure

[ScottS97385]

Just a heads up.While doing some winter maintenance I drained the header tank and checked the low fuel warning system. It wasn't working so I investigated further and found the sending unit had failed and the float was rattling around in the small tank.

I found a new sending unit on Amazon.







29641

[DesertFox4]

Had the same issue Scott on my low fuel warning after only 9 months in service. Took the whole system out after the second sender failed shortly after. Seems the senders available now have low quality. Not sure if the fuel causes the plastic they use to become brittle or they start out that way. The little “tabs” break off and the sender becomes in-op.
I made sure when initially inserting the senders into the little tank that I followed the proceeder to rotate the tank as the sender screws into the tank so the sender does not bind on the inside of the tank and break off the little pivot tabs before you get a chance to use it. It still failed prematurely. The confidence factor for me dissipated with the loss of reliability. The Kitfox fuel sight gauges are reliable.

[109JB]

Ever since I got my Murle Williams header tank with the low fuel sensor I have wondered why use the float sensor like that. Cars have been using a thermistor for low fuel sensors for oh I don't know about 50 years or more. The thermistor is submerged in the fuel and the heat dissipates in the fuel and resistance remains high. Once fuel is off of the thermistor (low fuel state), it heats up and then the resistance lowers and the light which is in series lights up. No moving parts. No float to come loose, etc. Here is how it works. If the float sensor that came with my header tank fails, it will be replaced with a thermistor based sensor

https://youtu.be/UEmbRJKlSeI

[napierm]

They don't last forever either.

https://www.youtube.com/watch?v=gjREKxkUtU4&t=0s

I see the problem of fabrication. Needs a mechanical mount that will give terminals and will be fuel (ethanol) proof.

[Eric Page]

External low level alarm (nothing inside the tank or in contact with fuel):

The sensor: https://teamkitfox.com/Forums/threads/11143-New-Low-Fuel-Alarm-Sensor?p=95576&viewfull=1#post95576

The interface: https://teamkitfox.com/Forums/threads/11143-New-Low-Fuel-Alarm-Sensor?p=98154&viewfull=1#post98154

I have two of the EFIS interface boards remaining.

[109JB]

They don't last forever either.

https://www.youtube.com/watch?v=gjREKxkUtU4&t=0s

I see the problem of fabrication. Needs a mechanical mount that will give terminals and will be fuel (ethanol) proof.

Well yeah, nothing lasts forever, but I've had many cars and motorcycles with thermistor based low fuel sensors going back decades and I have personally never had one fail and I do put them to the test. On ground based vehicles I tend to go until the light comes on at least in the summer.

As far as fabricating a mount, A little fuel tank repair epoxy and a brass NPT fitting takes care of that, or if you want one store bought, just buy one that screws in.

https://www.partzilla.com/product/honda/37810-MFE-641?gclid=CjwKCAiAlfqOBhAeEiwAYi43FzCBO1VgxAB1tQvf HxwZ9b1gBdNkMP4za7gl5Yjsz6nC2GQ3r5tDXBoCp-oQAvD_BwE

Not for everyone, but I personally prefer the no moving parts option and if my float sensor that came with my header tank ever fails it will get a thermistor based unit.