40 Deluxe fuel gauge

M

magzboy

Junior Member
Hi guys. Fitted a new Drake fuel tank and sender unit. After a year of working not too bad (drops to quarter tank and stops there) it now just goes to full upon switching on and stays there Any help would be appreciated before new gauge or sender is bought. Kiwi dollar only buying US .60c so that exchange rate and the exorbitant postage these days make for careful purchases.
 
You can buy or make an adapter that will allow you to install the OEM gas tank sending unit to the DRAKE tank.
THE OEM GAS GAUGE WILL NOT WORK ACCURATELY USING THE DRAKE SENDING UNIT so don't take the chance on damaging your OEM fuel gauge by trying to install a gas tank sending unit that works on the Ohms principle. The OEM fuel gauge and the OEM gas tank sending unit were both made by King-Sealy and were made to work together with each other.
 
Agree, the original gauge will never be accurate with an aftermarket sender. But maybe you can get it back to where it was, needle moves but with inaccurate readings.

Gauge needle going to full indicates a direct short somewhere in the sender sub-circuit. Look for a place where sender wire (yellow) is going to ground.
Or...could be an internal short within the sender itself. Don't know how you could fix that. But maybe worth a try to pull the sender and look at it.

Edit: Disconnect the wire at the sender and see what the needle is doing. If still going full, short is in the wiring. If it stays at empty, short is in the sender.
 
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A full reading all the time indicates a loss of ground on the sending unit. Happens all the time on these old cars. Run a jumper wire from one of the sender mounting bolts to a good ground.
 
Planojc said:
A full reading all the time indicates a loss of ground on the sending unit.
Click to expand...
Planojc, One of us is wrong, has the thinking backwards.

On the temperature gauge a loss of ground on the sender will produce full gauge reading. I think opposite is true on the fuel gauge.
 
Thanks to all you guys for the advice. Scuff plates were installed recently and maybe a screw has nicked a wire. Off i go investigating.
 
Planojc. Found that the scuff plate had squished the wire down and created a 'ground'. Problem solved thanks to all you guys advice. I now have a NOS fuel gauge coming that will join all the other parts on the shelf, as in Burt Munro's words, "offerings to the god of speed ". One happy Kiwi again. Thanks you all.
 
19FORDY. Talking to Drake and they only do an adaptor for 33/35 tanks. Problem was a grounded wire after scuff plate install. Thanks.
 
I found this thread while testing an original '40 sending unit and gauge.

I opened up the sending unit, took the mechanism out and cleaned the points.

I read about the principle behind it, still can't quite understand it, but seems I got the unit going. Also adjusted it by the small toothed wheel. Seems to display the different positions correctly.

However, is it correct the gauge isn't steady? Its seems to 'pulsate' around it's approximate position: small current flows, the needle moves. Then the current stops and the needle drops a little bit. Current flow again, etc., etc.

I have a video, but that's probably too large too post.

Dennis

Verstuurd vanaf mijn SM-S931B met Tapatalk
 
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