Fuel Sender and Fuel Tank queries

What is the easiest way to check a fuel sender unit when it is not in the truck?

The fuel sender unit in my AR162 does not work. The gauge has been tested a couple of times by grounding it at both the back of the gauge and at the fuel tank end and it moves but it doesn't work when attached to the sender unit.

The tank on my AR162 is behind the step, under the cab on the left hand side. The previous owner told me that he had also tested the gauge and tried to remove the sender unit but there wasn't the space between the top of the tank and the floor of the truck.

I got a 2nd hand tank almost 2 years ago when I was purchasing some other Inter bits and this came as part of the set. It has a sender unit that I finally got around to pulling out today and it looks to be in good condition but I want to test it before fitting it.

On a related issue am I better off cleaning out the spare tank, checking it for leaks and if everything is ok just swapping them over or just swapping over the sender units in the existing tank on the basis it is giving me no problems? The tank will have to come out to swap the sender unit.

A third option is to put a 140 litre tank I have been offered on the chassis behind the cab. The advantage of this is that if an accident happens the passenger isn't sitting on top of the fuel tank. The original tank is 80 litres.

Of course I could always twin tank it which should give me the range on runs. I can't get a return trip to Bendigo out of the AR at present.

any ideas are welcome

The sender is a variable resistor.. check it with a Multimeter.. one lead on the connector.. one on the body of the unit.. Move the float up and down and you should see the resistance change..

I have no idea what the resistance range would be for your unit though.

Dunc.

4th option is keep the 80 litre tank and put in a 200 litre gas tank behind the cab and you will make Bendigo couple time before filling. Dave

If you go twin tanks you normally have a cross over pipe or hose at the bottom. This needs to be protected against damage otherwise you can lose all the fuel in one go.

If you go twin tanks you normally have a cross over pipe or hose at the bottom. This needs to be protected against damage otherwise you can lose all the fuel in one go.

Hey Pete,

Tell me about it - mum, dad and I were coming home from Sudney last Xmas and after Victoria Pass on the Gt. Western Highway, we were cruisin' along and then all of a sudden we saw a paddy wagon and a fire truck - I was thinking, "What's going on?" and it wasn't until we got around the bend when we saw a Freightliner Argosy with the hose you mentioned pulled out of the bottom of the driver's side fuel tank! 500m behind the truck was as slippery as hell due to the diesel mixing with the water on the road surface because it had been raining! The Hazmat truck (well it wasn't a truck moreso than a van) was there and a firey was under the tank decanting what diesel was left in the tank into one of those orange chemical drums so the man from Pirtek could get under and re-fit the fitting - I think he might have lost 80% of the fuel out of that tank and 10% from the left tank! Someone would have had a massive cleanup bill or not - could have claimed it was an accident!

Joe

Yes, it does happen, common on a rigid truck because the longer wheelbase means you are likely to bottom out there when going up a driveway or suchlike. Maybe there is a better way to do it ie an electric pump or something

Bparo,

To test your fuel tank sender :
Get a multimeter and set it to the 0 - 100 ohms scale, if it doesnt have the word ohms it will have the ohms symbol [ch8486]
Put the black probe on the sender mounting mounting flange and the red lead on the post where the wire goes.
With the float in the empty tank position you should have 30 ohms.
In the full tank position you should have 0 ohms.
Use a piece of wire through your filler hole to twiddle the float arm up and down.
If you see 90 ohms in the empty position dont be alarmed as some of the later ones were 0 - 90 ohm.
A note for all you need the right gauge and senders as a pair to work properly. ie 0-30 sender = 0-30 ohm gauge.
Most aftermarket modern senders are 240 - 33 ohms and wont work with the early gauges.
Barry

Thanks Barry. I will give it a try (probably next weekend as work/yearbook is keeping me busy midweek).

I wasn't going to twin tank it in the coventional sense where fuel is drawn from both but mount the second tank in the chassis behind the first at a higher level (so say the bottom of the 2nd tank is halfway up the side of the first) with the line from it having a tap on it and entering the first tank.

This way I can close the tap and only use the original tank when on a short run but can fill both tanks before leaving on a long run then open the tap when I stop for a coffee or something 2 to 3 hours down the road and have gravity feed the fuel from the new (higher) tank into the first tank.

If I mount it correctly the lines shound be attached to the side of the chassis and not get caught and ripped out

It is a petrol truck and petrol goes off so I normally fill as I leave for a run, not as I store the truck. Using this setup means I only purchase what fuel I need for the planned run and is safer and cleaner than carrying and filling from jerry cans enroute. It would enable me to get to say Beaufort and return without needing 3 topups enroute