Fuel sender unit problem

[pupinabox]

Got my tank pulled and cleaned and coated with POR15. Replaced the sender unit as the fuel gauge never showed more than about 3/4 full. Before I put the new sender in I hooked it up and moved it up and down and CRAP..it does not go over 3/4 full!!

I think I saw on here a while ago someone said they just moved the needle on the gauge to full when the tank was full(?) Can you do this? I guess I will make sure all the electrical connections are good and clean, but after that, I am at a loss.

PS: I don't know if it means anything, but the low fuel light never came on when I was moving the sender arm up and down. Maybe the bulb is out. Just another clue.

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[jclay (RIP 2018)]

I had the same problem. Now replace the gauge!

There is a delay system in the line. If you don't wait for a while, the light will not come on.

Clay

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[pupinabox]

will check that delay as tank is still empty.[:(!] I guess I only gave it the time to move the arm then crawl out from under the car and look.

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[jclay (RIP 2018)]

If the tank is empty, then the light should come on. The delay unit is attached to the instrument cluster on one of the upper corners. There are 4 wires attached to it.



According to Odd it's:

T = Green/Orange
L = Light-Green/Red
E = Black
B = Green

Basically, it's a bimetallic strip that bends when heated to make an electrical circuit with an adjustable contact.



Clay

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[FI Spyder]

<blockquote id="quote"><font size="1" face="Century Gothic, Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by pupinabox</i>

I guess I will make sure all the electrical connections are good and clean, but after that, I am at a loss.
<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">

The sender is a rheostat that varies the resistance as the arm moves. Any dirty connection, bad connection to wire contact either at the sender end or the gauge end will introduce resistance that will affect the needle position. Short of that there is always the possibility of the connecting wire may have broken strands. If none of these then it is the guage faulty. You can try moving the needle as, if it breaks you had to get a new one anyways (if you want an accurate reading).


TR7 Spider - 1978 Spifire - 1976 Spitfire - 1988 Tercel 4X4 - Kali on Integra - 1991 Integra

[Odd]

You want the gauge to read correctly when the tank is <u>almost</u> empty - the 'full' end is of less importance...

[Hasbeen]

I'm with you Odd.

None of my 7s have ever read more than a touch over 3/4, when full.

As they all took a little over 25L to fill with the gauge around
half, I reckon they are about right from there down to empty, &
that's the important end.

I have no idea if the low fuel light still works, the fuel has not
got below 3/8Ths full in years.

Hasbeen

[FI Spyder]

<blockquote id="quote"><font size="1" face="Century Gothic, Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Odd</i>

You want the gauge to read correctly when the tank is <u>almost</u> empty - the 'full' end is of less importance...
<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">

True but I like my gauge to read full when full and empty when empty. (It does). My low fuel light came on when needle was on or pretty on E (I was lowering level in preperation of removing tank.) I usually never let my fuel tank go below half way to minimize condensation. Always done it except for long drives in my Javelin 304 which had a small tank and one time the gauge stuck at 1/4 in the middle of the night and I ran out of fuel in the middel of nowwhere. Luckily there was a Motel a 1/4 mile back that I could call an all night garage station for a tow truck to come out with gallon gas can. Onjly time it ever happened.

Anyway, my sender reads 18.9 ohms at one end (I imagine that's full needle deflection...full). What's yours read?


TR7 Spider - 1978 Spifire - 1976 Spitfire - 1988 Tercel 4X4 - Kali on Integra - 1991 Integra

[Beans]

In my Sprint the fuel warning light went on only once.
And when I pulled into a fuel station only 2 miles further down the road the engine cut out ...
The tank indeed was very empty, I managed to put nearly 62 litres of fuel in.

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