Low Petrol Warning Light ?

[Nickleback]

Since I have had my car (18 months) the low petrol warning light has never worked.

Firstly, would I be right in assuming that when the ignition light is on before starting the car, this light would also be on ? if yes, then it is not.

I have replaced the bulb with one which definitely works, have checked the bulb holder earth - both are OK.
I have checked in the bulb holder with a multimeter for live feed in which is 12v and all OK.
I have also checked wiring connections / colours against diagram back to the harness and all appear to be OK.

So why wont it work with the ignition light on
or does it only come on when the petrol is low so there is no other way of checking it first

[Gfhug]

Mike, I can't claim to have ever seen it come on when turning on the ignition, but it definitely works on my car, with about 1 1/2 gallons left in the tank.
Maybe you'll just have to run low and be prepared to push the car home if the light doesn't work

Cheers
Geoff

[kingzetts]

Mike,
In the S1, the bulb is f d 12V when the ignition is on, and is earthed via contacts in the fuel level transmitter assembly when the level gets low enough. It is not earthed via the bulb holder and the bulb will not come on with the ignition light. The S2 is probably the same. The giveaway will be two wires to the bulb holder - only one needed if the holder provides the earth.

Options to check - run the fuel down as Geoff suggests, or remove the boot boards and remove the fuel level unit from the tank.

[Nickleback]

Definitely two wires go into the back of the bulb holder, one green & the other green / black from memory.
I guess it looks like I need run it really low and carry a spare fuel can to test / check
Thanks guys

[1954Etype]

Mike, remove lh boot board, remove white/green and with ign on, earth out the lead. The low warning light should come on. This will prove the circuit works. If it does, my money would be on the low indicator working as well.

[cactusman]

Think the wire from the bulb to the tank sensor is white with green stripe. Try grounding the wire at the sender and check the bulb lights? As you run low the bulb will start to light briefly under breaking as the petrol sloshed to the front. Once it is permanently lit you are on vapours!!! Mine works fine.

[Nickleback]

Well, I earthed out the white /green lead on the sender and the light now works, thank you gentlemen

So the original problem was a blown bulb, bent and loose collar around bulb holder which was not located in the speedo as it was " swinging in the breeze" behind the dashboard, no wonder I could'nt see it !

[chrisfell]

I have a light that won't go out at all. The sender is at fault. I have a replacement, but I'm waiting until winter fettling to sort it out.

[cactusman]

Easy job. Six small bolts to remove and out comes the sender. Don't forget to isolate the battery first and its worth while changing the gasket at the same time. Takes twenty mins to change....do it.

[1954Etype]

Julian, hmmmm not so sure. Isolate battery. Disconnect contacts. Remove soft headed cheese screws taking care not to chew up the heads. Assuming they all come out, anneal or replace the copper sealing washers making note of which ones were doubled up and where the earth tag was fitted. Clean gasket faces on tank and sender unit. Fit new cork gasket (we use silicone sealant). Screw sender down evenly tightening as you go. Take care not to over tighten or the gasket might spread. Leave for 30 mins then check tightness of screws. Re connect 3 wires and battery. Finally check for leaks.

[PeterCrespin]

Silicone works OK in the short term but is not really impervious to fuel.

Pete

[Heuer]

If the gasket is rubber then red rubber grease works as it is impervious to petrol or oil. Hylomar would also work but silicone is a big no-no where fuel is concerned.

[Nickleback]

I used Hylomar Blue, works a treat near petrol.

[1954Etype]

Pete, the stuff we use is recommended for sealing inlet manifolds so l assume it is ok.

[Heuer]

When I had the leaking submersible fuel pump I tried sealing the cable gland with silicone. It lasted about 48 hours before fuel started to seep back up the cable. I could simply pull the silicone away in bits.

[cactusman]

Well Andrew. I have removed and refitted mine in less than 30 mins. Obviously if things go wrong then, yes, it may take longer . Providing you have the correct tools, a new gasket and a camera to photo if you are unsure where the earth tag goes then it really is not tricky. The screws are not done to any significant torque so providing the copper washers are not mis sharpen or cracked then they can be 're used . I think annealing is going a bit far. A smear of gasket sealant e.g. hylomar if you like but the thing is at the top of the tank so probably not needed. I did not bother and there is n o hint of fumes or leaks. Many a job on an e is tricky and time consuming but imo removing the sender is one of the simpler tasks.

[PeterCrespin]

Pete, the stuff we use is recommended for sealing inlet manifolds so l assume it is ok.

Many modern inlet manifolds never see petrol, breathing only air until just upstream of the valve, or not even then if direct injection. And since half the cars are diesel it applies even more.

Room Temp Vulcanizing silicone works on sealing air and water passages. Even around an inlet port the main gasket face should not see fuel, but it's not right for petrol and petrol does pool in the base of the runner where the gasket is narrowest. Fuel doesn't pool on a running engine and hardly at all on a downward-angled E manifold, but still....

Blue Hylomar, Red Hermetite etc. are what I'd use, even if 95% of the time there'd be no difference.

[cactusman]

I always have a tube of blue hylomar in stock