Fuel gauge 90 300TDi

Landyfox · Dec 8, 2017

can anyone confirm what shares the earth with fuel gauge?

Since filling the old girl up a few month ago, the gauge reads stone empty. Everything else appears to be working. The gauge literally sits at the bottom below the empty mark and never moves. It does illuminate, although I expect that is on a separate circuit.

Also, I’ve fitted a later TD5 bonnet to my early 300TDi. Although it looks exactly the same from the outside, there are some differences underneath. Firstly, I can’t figure out how to fit the bonnet stay as there is nowhere to bolt it on. And finally, it doesn’t shut fully, the coolant reservoir appears to hit the underside preventing it from sitting flush like my old bonnet. I can’t lower the reservoir as it hits the suspension capping in the wing.

Anyone else had similar experiences?

jamesmartin · Dec 8, 2017

td5 bonnet stay is mounted to rad frame
non reading at all suggest other than poor earth

Roaming Wombat · Dec 8, 2017

sounds like could be your fuel sender unit, check the connections on top of your fuel tank, then check the interconnect in the engine bay by the bulkhead to make sure the connection there isn't loose.

Checking the sender can be done by measuring the resistance across one of the pins and the earth pin. The sender is easy enough to remove, just remove the driver's seat and chap the lock ring round to release the sender.

You can also try swapping the connection on the back of the fuel gauge with the connection on the coolant gauge. The needle on the coolant gauge should move with ignition on.

if the sender is duff its worth noting the pins may not necessarily be in the same matching order on the new unit (easier enough to work out with an multimeter).

Landyfox · Dec 9, 2017

Roaming Wombat said:
sounds like could be your fuel sender unit, check the connections on top of your fuel tank, then check the interconnect in the engine bay by the bulkhead to make sure the connection there isn't loose.

Checking the sender can be done by measuring the resistance across one of the pins and the earth pin. The sender is easy enough to remove, just remove the driver's seat and chap the lock ring round to release the sender.

You can also try swapping the connection on the back of the fuel gauge with the connection on the coolant gauge. The needle on the coolant gauge should move with ignition on.

if the sender is duff its worth noting the pins may not necessarily be in the same matching order on the new unit (easier enough to work out with an multimeter).

Thanks RW - I will try this on Sunday and feed back

Landyfox · Dec 9, 2017

jamesmartin said:
td5 bonnet stay is mounted to rad frame
non reading at all suggest other than poor earth

Ah bugger. I’ve only got a 300TDi stay, is there a way to retro fit it, or can you direct me to the part. Thanks James

Kwakerman · Dec 9, 2017

Landyfox said:
Ah bugger. I’ve only got a 300TDi stay, is there a way to retro fit it, or can you direct me to the part. Thanks James

There are two types of stay, my 300 CSW uses the top style, is that what you have?

Roaming Wombat · Dec 9, 2017

I use a piece of 2x4 (came complimentary with my Landy)

Landyfox · Dec 9, 2017

Kwakerman said:
There are two types of stay, my 300 CSW uses the top style, is that what you have?View attachment 136417

Great thank you

Just need to figure out how to make it close properly now.

Kwakerman · Dec 9, 2017

Landyfox said:
Great thank you

Just need to figure out how to make it close properly now.

Do you need any pics of how the scissor one fits?

Landyfox · Dec 9, 2017

Kwakerman said:
Do you need any pics of how the scissor one fits?

Thanks K - It would seem you can’t fit the scissor one to the TD5 bonnet (huffing)... I’m amayzed that the bonnets are different. But if you’ve got pics showing how I can do it, then; YES PLEASE!

Kwakerman · Dec 9, 2017

Landyfox said:
Thanks K - It would seem you can’t fit the scissor one to the TD5 bonnet (huffing)... I’m amayzed that the bonnets are different. But if you’ve got pics showing how I can do it, then; YES PLEASE!

Ok, will see what I can do tomorrow

Landyfox · Dec 12, 2017

Roaming Wombat said:
sounds like could be your fuel sender unit, check the connections on top of your fuel tank, then check the interconnect in the engine bay by the bulkhead to make sure the connection there isn't loose.

Checking the sender can be done by measuring the resistance across one of the pins and the earth pin. The sender is easy enough to remove, just remove the driver's seat and chap the lock ring round to release the sender.

You can also try swapping the connection on the back of the fuel gauge with the connection on the coolant gauge. The needle on the coolant gauge should move with ignition on.

if the sender is duff its worth noting the pins may not necessarily be in the same matching order on the new unit (easier enough to work out with an multimeter).

Right I’ve braved the snow and ice and still can’t figure the bugger out.

I checked the resistance across the pins and it was zero. I then swapped the green cable over to the coolant gauge and nothing. Didn’t budge. No fuse are blown and all the connections seem clean with good contact.

Is it looking like the sender has had it?

Also, has anyone fitted a new heater cable, the one which controls the fan. The sheath has completely come away from mine. Must get some heating sortedin this weather lol

Roaming Wombat · Dec 12, 2017

Are you getting continuity between the sender and the cable on the back of the gauge?

Looks like the sender is goosed if the connections are all there (I got caught out by the ones in the engine bay), sender's are about £20 (paid £22inc. VAT for mine) and as you probably noticed its a quick job, just double check the pins on the new one for which is which.

jamesmartin · Dec 12, 2017

Landyfox said:
Right I’ve braved the snow and ice and still can’t figure the bugger out.

I checked the resistance across the pins and it was zero. I then swapped the green cable over to the coolant gauge and nothing. Didn’t budge. No fuse are blown and all the connections seem clean with good contact.

Is it looking like the sender has had it?

Also, has anyone fitted a new heater cable, the one which controls the fan. The sheath has completely come away from mine. Must get some heating sortedin this weather lol

if you earth feed wire to sender does gauge rise

Landyfox · Dec 12, 2017

Sorry schoolboy error. When I swapped wires over on the fuel/coolant gauge, I only swapped over the green wire (female connectors). Tonight there, I've noticed that at the bottom right of the fuel gauge there is a green/black wire (male spade connector). I've swapped that one over to the coolant gauge and started the ignition, it quickly went up to halfway. I swapped it back and connected up to the fuel gauge, nothing, didn't move at all. Turned ignition back off and on and it moved up to just below the empty line. Switched ignition back off and on again.... nothing, again it didn't move. I tried this 3 more times with no movement then once again it moved up just past the Empty line and touching the orange. Switched on and off again 7 times and nothing. Tank is 3/4 full.

I'm completely at a loss!!!!

Roaming Wombat · Dec 12, 2017

Sender is fine then, and the connections, last thing before condemning the fuel gauge would be to clean up the terminals.
Giving the the connectors on the back of the gauge a good "twiddle" could yield something but really it looks like your gauge is goosed.

Final check would be James Martin's suggestion of earthing the sender feed wire at the sender.

Landyfox · Dec 12, 2017

Roaming Wombat said:
Sender is fine then, and the connections, last thing before condemning the fuel gauge would be to clean up the terminals.
Giving the the connectors on the back of the gauge a good "twiddle" could yield something but really it looks like your gauge is goosed.

Final check would be James Martin's suggestion of earthing the sender feed wire at the sender.

So does James mean just pull the black wire off the sender and connect a direct earth to the neg battery terminal to test. Then remove the green wire at the Sender end and earth that directly? I'm assuming the ignition still needs to be on? How thick am I feeling!!!

James and RW I really appreciate this help, thanks

jamesmartin · Dec 12, 2017

Landyfox said:
So does James mean just pull the black wire off the sender and connect a direct earth to the neg battery terminal to test. Then remove the green wire at the Sender end and earth that directly? I'm assuming the ignition still needs to be on? How thick am I feeling!!!

James and RW I really appreciate this help, thanks

just put live from gauge at the sender green to earth chassis or body

Landyfox · Dec 12, 2017

jamesmartin said:
just put live from gauge at the sender green to earth chassis or body

When doing this James what should I expect to happen? I will do it first thing in the morning and report back. Hope it is fixable, I could do without HAVE to fork out for a replacement gauge at this time of year!

jamesmartin · Dec 12, 2017

gauge to rise to full

Fuel gauge 90 300TDi

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