Unplugging fuel pump connector?

gnu · 27th December 2021, 13:21

Pretty basic, but I'm trying to unplug the connector on the ZT fuel pump so I can take some resistance readings i.a.w. T-Cut's diagram. The connector top sleeve slides towards the o/s door about 10mm, but the connector won't pull off. I'm being gentle as I don't want to break anything. Am I misunderstanding how this connector works? Has anyone a video/ pics of how it disconnects?

Why am I doing this? The instrument panel gauge is reading wrong again, some times past the full mark!
The IPK test indicates ~
6.0 000 (this would normally be something like the 6.2 reading)
6.2 545

The tank is pretty full atm so 54 litres could be correct. I was wanting to check whether the variable resistor is giving a realistic reading on both sides...

COLVERT · 28th December 2021, 09:33

Have a look in the clubs general forum.---Some info there that might be of help to you with your fuel gauge problem.

Under--Fuel gauge fault.--Yours could be the same.--

T-Cut · 28th December 2021, 10:22

Quote:

Originally Posted by gnu

Pretty basic, but I'm trying to unplug the connector on the ZT fuel pump so I can take some resistance readings i.a.w. T-Cut's diagram. The connector top sleeve slides towards the o/s door about 10mm, but the connector won't pull off. I'm being gentle as I don't want to break anything. Am I misunderstanding how this connector works? Has anyone a video / pics of how it disconnects?

Hello Michael, addly enough I've never had reason to disconnect the pump, so all I can tell you is what Haynes says:
Release the locking catch and disconnect the wiring connector.

Not very informative, but releasing a catch seems different from sliding the connector top sleeve. Is the sleeve a protective cover rather than a catch? I've no idea.
I'm sure someone here will know exactly how to do it.

TC

gnu · 28th December 2021, 16:32

Thanks TC. I got the connector off no problem today, when it wasn’t pouring with rain and I wasn’t kneeling in a puddle! I sprayed with contact cleaner, and that broke whatever was bonding it in place.

In the checks: Pin 1/4 in spec (177ohms). Pin 5/2 in spec. Pin 6/3 open circuit. The open circuit might explain the 6.0 ipk reading being 000, although the reading sometimes changes to something like the 6.2 reading (544) whist driving around.

The problem could be a bad connection or broken cable to the fuel filter sender in the tank. As the tank is pretty full, nothing I can do atm. I’ll monitor and maybe try to fix when emptier.

Gauge is reading 7/8, which is plausible, but sometimes goes well past 8/8, even when ignition is switched off. I’ve read that there is some sort of algorithm in the control unit that decides what the gauge reads depending on the sender input and applies some ‘damping’ to stop sloshing affecting it. This is my first 75/ ZT and the only car I’ve had which the fuel gauge can’t be trusted.

COLVERT · 28th December 2021, 20:51

My post 2 no interest to you then??------

gnu · 28th December 2021, 22:08

Quote:

Originally Posted by COLVERT

My post 2 no interest to you then??------

Yeah thanks read the posts on similar probs and used the fuel pump pin diagram to test resistance.

27th December 2021, 13:21	#1
gnu Gets stuck in MG ZT Join Date: Apr 2018 Location: Bristol Posts: 695 Thanks: 332 Thanked 164 Times in 133 Posts	Unplugging fuel pump connector? Pretty basic, but I'm trying to unplug the connector on the ZT fuel pump so I can take some resistance readings i.a.w. T-Cut's diagram. The connector top sleeve slides towards the o/s door about 10mm, but the connector won't pull off. I'm being gentle as I don't want to break anything. Am I misunderstanding how this connector works? Has anyone a video/ pics of how it disconnects? Why am I doing this? The instrument panel gauge is reading wrong again, some times past the full mark! The IPK test indicates ~ 6.0 000 (this would normally be something like the 6.2 reading) 6.2 545 The tank is pretty full atm so 54 litres could be correct. I was wanting to check whether the variable resistor is giving a realistic reading on both sides... __________________ gnu

28th December 2021, 09:33	#2
COLVERT This is my second home R75 Saloon. Join Date: Feb 2009 Location: France/or Devon. Posts: 14,003 Thanks: 3,851 Thanked 2,167 Times in 1,816 Posts	Have a look in the clubs general forum.---Some info there that might be of help to you with your fuel gauge problem. Under--Fuel gauge fault.--Yours could be the same.-- Last edited by COLVERT; 28th December 2021 at 09:36..

28th December 2021, 16:32	#4
gnu Gets stuck in MG ZT Join Date: Apr 2018 Location: Bristol Posts: 695 Thanks: 332 Thanked 164 Times in 133 Posts	Thanks TC. I got the connector off no problem today, when it wasn’t pouring with rain and I wasn’t kneeling in a puddle! I sprayed with contact cleaner, and that broke whatever was bonding it in place. In the checks: Pin 1/4 in spec (177ohms). Pin 5/2 in spec. Pin 6/3 open circuit. The open circuit might explain the 6.0 ipk reading being 000, although the reading sometimes changes to something like the 6.2 reading (544) whist driving around. The problem could be a bad connection or broken cable to the fuel filter sender in the tank. As the tank is pretty full, nothing I can do atm. I’ll monitor and maybe try to fix when emptier. Gauge is reading 7/8, which is plausible, but sometimes goes well past 8/8, even when ignition is switched off. I’ve read that there is some sort of algorithm in the control unit that decides what the gauge reads depending on the sender input and applies some ‘damping’ to stop sloshing affecting it. This is my first 75/ ZT and the only car I’ve had which the fuel gauge can’t be trusted. __________________ gnu

28th December 2021, 20:51	#5
COLVERT This is my second home R75 Saloon. Join Date: Feb 2009 Location: France/or Devon. Posts: 14,003 Thanks: 3,851 Thanked 2,167 Times in 1,816 Posts	My post 2 no interest to you then??------