How many fuel tank senders ?

Sonic ZS · 17th August 2020, 16:48

Hi all, could someone confirm whether all 75/ZT's had two fuel tank sender units, or was the N/S unit dropped later in production ?

I have a friend telling me he only has one (O/S) in a late model ZTT 1.8, or poss 1.8T ??

Is the N/S unit difficult to see or something, maybe housed within the filter so not immediately obvious ?

Many thanks

Ched · 17th August 2020, 16:56

Yes there are 2, Ive just replaced a complete system twice, both from different era's and both have two sets of floats.
It is very possible that the float assy on the n/s has become detached or not even put back in the correct place hence it not being seen

T-Cut · 17th August 2020, 17:22

Quote:

Originally Posted by Sonic ZS

I have a friend telling me he only has one (O/S) in a late model ZTT 1.8, or poss 1.8T ??

If his gauge is reasonably accurate against the juice he puts in the tank, then both floats are working. If one wasn't, the gauge would tell a different story.

Quote:

Is the N/S unit difficult to see or something, maybe housed within the filter so not immediately obvious?

Both have an external float arm attached which operates a rheostat. The combined resistance of the rheostats determines the indicated contents of the tank.

TC

Sonic ZS · 17th August 2020, 22:23

Many thanks for the replies gents, I will get back to him tomorrow and tell him to find the N/S unit. Apparently the gauge is reading empty all the time with the fuel warning light on, so looks like it may be the N/S sender that's at fault

T-Cut · 17th August 2020, 23:12

There's a simple check he can make to confirm whether the rheostat is faulty or if it's the float that's jammed/not floating correctly. The RHS module has the connector for the wiring harness. With that detached, measure the resistance across the pins indicated in this diagram.

This will inform you about the state of the system.

TC

Sonic ZS · 17th August 2020, 23:20

That's excellent, thank you. I'll pass on the info tomorrow, hopefully he'll be able to get the gauge working again

T-Cut · 18th August 2020, 08:19

Problems with the floats are typically the result of someone taking the float or pump module out of the tank for some reason. They can be very fiddly to refit. The filter module may also require the orange clip, so it's worth checking that out at the same time. If the filter needs the clip it should be fitted while everything's opened up.

The floats can be compromised by faulty refitting, so it doesn't swing freely across the range. Sometimes the rheostat contact brush wears through the windings or lifts off in certain positions. There's a HowTo on this somewhere.

TC

picky747 · 18th August 2020, 11:05

Never sits well with me seeing exposed electrical components sat in a tank of fuel but it seems to work!!!

T-Cut · 18th August 2020, 16:22

Quote:

Originally Posted by picky747

Never sits well with me seeing exposed electrical components sat in a tank of fuel but it seems to work!!!

It's counterintuitive because you see the obvious likelyhood of a spark, especially on the rheostat brush or within the pump. The pump armature and brushes are submerged in petrol. But even if there was a spark (and I dare say it happens), it's perfectly safe because there's no oxygen in the tank to allow a fire. Fire needs three things at the same time (fuel, heat and oxygen). Remove one and no fire is possible.

TC

Sonic ZS · 18th August 2020, 23:53

Just to update on this one, I took along the details today and found out that a previous quick look at the top of the N/S unit showed no wiring, hence the assumption there was no sender !

Anyway, checked the wiring connections in the pump side (which seemed reversed to the diagram strangely), but resistance values were within tolerence - thanks again

so the investigation is now moving to the wires in the loom, to see if there's a break somewhere

17th August 2020, 16:48	#1
Sonic ZS Posted a thing or two 75 Conn CDT Tourer, 75 Conn SE V6, 75 Conn V6, 75 Conn CDTi Tourer, ZS 180 Join Date: Jan 2014 Location: Devon Posts: 1,986 Thanks: 1,287 Thanked 963 Times in 534 Posts	How many fuel tank senders ? Hi all, could someone confirm whether all 75/ZT's had two fuel tank sender units, or was the N/S unit dropped later in production ? I have a friend telling me he only has one (O/S) in a late model ZTT 1.8, or poss 1.8T ?? Is the N/S unit difficult to see or something, maybe housed within the filter so not immediately obvious ? Many thanks __________________

17th August 2020, 22:23	#4
Sonic ZS Posted a thing or two 75 Conn CDT Tourer, 75 Conn SE V6, 75 Conn V6, 75 Conn CDTi Tourer, ZS 180 Join Date: Jan 2014 Location: Devon Posts: 1,986 Thanks: 1,287 Thanked 963 Times in 534 Posts	Many thanks for the replies gents, I will get back to him tomorrow and tell him to find the N/S unit. Apparently the gauge is reading empty all the time with the fuel warning light on, so looks like it may be the N/S sender that's at fault __________________

17th August 2020, 23:20	#6
Sonic ZS Posted a thing or two 75 Conn CDT Tourer, 75 Conn SE V6, 75 Conn V6, 75 Conn CDTi Tourer, ZS 180 Join Date: Jan 2014 Location: Devon Posts: 1,986 Thanks: 1,287 Thanked 963 Times in 534 Posts	That's excellent, thank you. I'll pass on the info tomorrow, hopefully he'll be able to get the gauge working again __________________

18th August 2020, 23:53	#10
Sonic ZS Posted a thing or two 75 Conn CDT Tourer, 75 Conn SE V6, 75 Conn V6, 75 Conn CDTi Tourer, ZS 180 Join Date: Jan 2014 Location: Devon Posts: 1,986 Thanks: 1,287 Thanked 963 Times in 534 Posts	Just to update on this one, I took along the details today and found out that a previous quick look at the top of the N/S unit showed no wiring, hence the assumption there was no sender ! Anyway, checked the wiring connections in the pump side (which seemed reversed to the diagram strangely), but resistance values were within tolerence - thanks again so the investigation is now moving to the wires in the loom, to see if there's a break somewhere __________________

17th August 2020, 16:56	#2
Ched I really should get out more....... MG ZT V8, MGZT 135 derv ,MG TF 135 Join Date: Dec 2011 Location: Romsey Posts: 2,293 Thanks: 553 Thanked 573 Times in 385 Posts	Yes there are 2, Ive just replaced a complete system twice, both from different era's and both have two sets of floats. It is very possible that the float assy on the n/s has become detached or not even put back in the correct place hence it not being seen

17th August 2020, 23:12	#5
T-Cut This is my second home Rover75 and Mreg Corsa. Join Date: Nov 2006 Location: Sumweer onat mote o'dust (Sagin) Posts: 21,753 Thanks: 341 Thanked 3,660 Times in 2,924 Posts	There's a simple check he can make to confirm whether the rheostat is faulty or if it's the float that's jammed/not floating correctly. The RHS module has the connector for the wiring harness. With that detached, measure the resistance across the pins indicated in this diagram. This will inform you about the state of the system. TC

18th August 2020, 08:19	#7
T-Cut This is my second home Rover75 and Mreg Corsa. Join Date: Nov 2006 Location: Sumweer onat mote o'dust (Sagin) Posts: 21,753 Thanks: 341 Thanked 3,660 Times in 2,924 Posts	Problems with the floats are typically the result of someone taking the float or pump module out of the tank for some reason. They can be very fiddly to refit. The filter module may also require the orange clip, so it's worth checking that out at the same time. If the filter needs the clip it should be fitted while everything's opened up. The floats can be compromised by faulty refitting, so it doesn't swing freely across the range. Sometimes the rheostat contact brush wears through the windings or lifts off in certain positions. There's a HowTo on this somewhere. TC

18th August 2020, 11:05	#8
picky747 Gets stuck in ROVER Join Date: Sep 2008 Location: Vera Posts: 746 Thanks: 56 Thanked 111 Times in 85 Posts	Never sits well with me seeing exposed electrical components sat in a tank of fuel but it seems to work!!!