Trouble with electric oil pressure gauge

[VYMAD]

I just fitted a Calibre oil pressure gauge and am not getting a reading, when engine starts the needle shoots up to 20 PSI, then straight back down to zero and stays there. I have spent hours mucking around with different earth points on the engine and on the chassis, but either way, there's no reading.
Any ideas? Faulty gauge/sender?

[wamboin23]

does it go all the way to full pressure when the key is on, the go back down once the engine starts? if yes, sounds like the sender unit you have is actually a switch.

did you fit the sender that came with the gauge or did you just tap into what is already there? because the stock one is just a switch.

[VYMAD]

I fitted the sender that came with the gauge.
The needle only goes up to twenty PSI, on a 140 PSI gauge for a second, then back to zero.

[VYMAD]

OK, me so happy! I took the gauge and sender back to the shop, swapped for another set and hey presto, all working.

[nalchlan]

hey you wouldnt happen to be able to post a pic of your diagram or briefly tell me where which wires go were? i got the crappiest diagram that is for an air/fuel anyway....