fuel gauge troubles! can anyone help me out here?

[geddron1976]

I recently decided to fit an onboard fuel tank as i was fed up with keep dragging jerry cans in and out of the boat. I bought a 53ltr plastic tank and a fuel sender unit but i already had a honda fuel gauge fitted on my console.
I have wired the gauge up like this:

12v+ from ignnition circuit to ign on gauge
ground has a wire going to ground on the battery and a second ground going to the fuel tank sender unit.
the sender wire is obviously to the sender terminal on the gauge.

i switched on the ignition with the tank empty and joyfully turned to see the gauge reading full!?

I tried switching the ground and sender wires from the sender unit, but it still reads full?

I then turned the tank upside down to simulate a full tank and the gauge reads empty...

now i may be slightly crazy at times but surely by switching the ground and sender terminals, shouldn't this have reversed the polarity of the senders signal?

I have thought about wiring the gauge up in the opposite polarity, but if i do this i will also have to wire the backlight up opposite as the ground terminal on the gauge is connected to the same terminal as the gauge ground.

any ideas how to fix this please?

i seem to have exhausted any options i can think of and i would rather not set fire to the new wiring loom.

Thanks in advance for your help..

Paul

 

[Bondo]

Re: fuel gauge troubles! can anyone help me out here?

Ayuh,... I can only Guess that the sendin' unit ya bought, just Ain't compatible with the gauge in yer dash,...

Fuel gauges measure varyin' resistance in the sender...
Different senders have different values than some gauges...

 

[gm280]

Re: fuel gauge troubles! can anyone help me out here?

NO NO NO don't reverse the gauge wiring. You know and so do I that that isn't the proper way to fix this problem. I'd do a good check on the tank wiring again AND check that the sender sensor is indeed good. If those things check out okay, then you have to have a wiring issue along the way to the gauge... Once you give in to reverse wiring things to make them work, you are asking for future problems at the least opportune time...and most of that time it would be out away from anybody OR a fire... You may have to use a good ohm meter and check the entire wiring issue to the meter to verify it is exactly like you think it is. Sensors can be checked with such a mtere as well because they are variable resistor units..JMHO! :nono:

 

[Don S]

Re: fuel gauge troubles! can anyone help me out here?

On the fuel sender you bought, turn the sender part (what the float is hooked to) over.

 

[geddron1976]

Re: fuel gauge troubles! can anyone help me out here?

On the fuel sender you bought, turn the sender part (what the float is hooked to) over.

Thanks for your replies..

I have checked the wiring and there doesn't seem to be any problems there. The 12v + is connected to the gauges (ign) terminal and is coming from the ignition circuit supplying 12v. The ground is connected to a good ground and the sensor wire is connected correctly.

The gauge is working but is reading opposite to what it should, ie empty when full and full when empty. when i turn the tank upside down it moves through the gauge as you would expect it to, only reading back to front.

I hve looked at the sender unit and i'm sure the type of sender you are referring to is the type that has the arm with a float on the end of it. unfotunately the type i have is just a post that goes from the top of the tank to the bottom and has what i believe is a magnetic float which slides up and down the post.

I am not going to wire the gauge to the opposite polarity as this is likely to cause a problem, particularly because the gauges backlight has the ground feed on the same connector as the gauges main ground connection and as was mentioned, this could lead to fires or simply an electrical failure when i could do without it.

I'm not sure if there is a way to reverse the gauge by changing the polarity of the sender, but as i mentioned before, even when i swap the wires round coming from the sender unit (ground and sender feed) the gauges still reads back to front.. it's all still making my head spin! lol

 

[Don S]

Re: fuel gauge troubles! can anyone help me out here?

unfotunately the type i have is just a post that goes from the top of the tank to the bottom and has what i believe is a magnetic float which slides up and down the post.

If that's the case, get rid of the Honda gauge, it reads senders backwards from most manufacturers. They do that so you have to buy only their products.

 

[geddron1976]

Re: fuel gauge troubles! can anyone help me out here?

Do you think there is anyway to open up the gauges and reverse it from in there? if im going to bin it, it might be worth a try before i do.

 

[Don S]

Re: fuel gauge troubles! can anyone help me out here?

No..

 

[UncleWillie]

Re: fuel gauge troubles! can anyone help me out here?

Common Fuel Sender Resistance....

Ohms/Resistance (Empty - Full)

240-33.5 - Industry Standard
0-200 - Honda
0-90 Ohms - GM cars, 1965 to present
0-30 Ohms - GM cars 1965 and Earlier
73-10 Ohms - Ford 1989 and Earlier & many Chryslers
16-158 Ohms - Fords, 1989 to present

 

[geddron1976]

Re: fuel gauge troubles! can anyone help me out here?

The sender I have is made by WEMA. I'm fairly certain it works on 0 - 190 Ohms.

When i go to buy a new gauge, is there anything specific i should ask for?

I mean, if the only difference in the honda gauge is that it reads 0 - 200 Ohms, is this why it reads backwards or is it just the internal workings that make it read backwards?
I wouldn't want to pay for another one and find it reads the same, the wife would kill me!

 

[Silvertip]

Re: fuel gauge troubles! can anyone help me out here?

Twenty bucks and your wife would kill you for that? Good heavens you better pray you never have an engine problem. Go right here on iBoats or if you are really not particular, try Great Lakes Skipper for NOS stuff including tons of instruments. And just so you know, reversing the electrical connections at the sender accomplishes nothing because the sender is a resistive element. As such it doesn't matter which way current flows through it, it ends up at the
"S" terminal of the gauge at the same value it did before.

 

[Don S]

Re: fuel gauge troubles! can anyone help me out here?

If you want to keep your Honda gauge so it matches everything else, just get a teleflex sender from here at iboats.

Then you can just turn the sender over so it will work with that gauge.