Petrol Tank
Forum rules
By using this site, you agree to our rules. Please see: Terms of Use
By using this site, you agree to our rules. Please see: Terms of Use
Petrol Tank
Hello,
I am recommissioning my G reg Minor Convertible after some years off the road. Decided to replace the petrol tank with a new one as old one was rusty and loads of gunge coming through to the carb.
Does anyone know whether the fuel pick up internal to the tank is fixed or does it move around on the end of flexi style pipe?
The reason I ask is because having put about a third of a tank of petrol in I still seem to be sucking in air.
Diagnostics are that if I disconnect the fuel line at the tank union and place that in a can of petrol the fuel pump runs OK and after a few seconds it cuts off and I can see fuel pumps through to an in-line filter between pump and carb.
As part of the commissioning I painted the fuel tank before installing it and it was upended and turned every which way; could this have dislodged the internal tank pick-up into a weird position?
Many thanks,
Gil.
I am recommissioning my G reg Minor Convertible after some years off the road. Decided to replace the petrol tank with a new one as old one was rusty and loads of gunge coming through to the carb.
Does anyone know whether the fuel pick up internal to the tank is fixed or does it move around on the end of flexi style pipe?
The reason I ask is because having put about a third of a tank of petrol in I still seem to be sucking in air.
Diagnostics are that if I disconnect the fuel line at the tank union and place that in a can of petrol the fuel pump runs OK and after a few seconds it cuts off and I can see fuel pumps through to an in-line filter between pump and carb.
As part of the commissioning I painted the fuel tank before installing it and it was upended and turned every which way; could this have dislodged the internal tank pick-up into a weird position?
Many thanks,
Gil.
-
stuffedpike20
- Minor Addict
- Posts: 888
- Joined: Thu Jul 26, 2018 7:40 pm
- MMOC Member: Yes
Re: Petrol Tank
The internal pipe is held in place by a metal tab that is bent over the pipe.
The pipe should not move even if you have moved the tank around a lot.
Maybe the copper pipe from the tank to the carb is not seating properly at the tank end?
I have found that if you do not use a tube nut spanner on the pipe to tank union, the union distorts and is hard to do up, or remove.
The pipe should not move even if you have moved the tank around a lot.
Maybe the copper pipe from the tank to the carb is not seating properly at the tank end?
I have found that if you do not use a tube nut spanner on the pipe to tank union, the union distorts and is hard to do up, or remove.
Re: Petrol Tank
Thanks for the confirmation of it being fixed in place
- svenedin
- Minor Legend
- Posts: 4741
- Joined: Fri Aug 29, 2014 9:27 am
- Location: Surrey
- MMOC Member: Yes
Re: Petrol Tank
I am not familiar with the term tube nut spanner. Do you mean a flare nut spanner as used on brake unions?stuffedpike20 wrote: ↑Wed Mar 25, 2026 9:15 am The internal pipe is held in place by a metal tab that is bent over the pipe.
The pipe should not move even if you have moved the tank around a lot.
Maybe the copper pipe from the tank to the carb is not seating properly at the tank end?
I have found that if you do not use a tube nut spanner on the pipe to tank union, the union distorts and is hard to do up, or remove.
What I would suggest to the OP is to disconnect the union from the tank and try again. Push the pipe into its seat and hold it firmly against the seat before tightening up the nut. As with plumbing compression fittings around the house (which have caused me much grief on microbore copper plumbing) there must be no strain on the pipe. It must enter its seat absolutely true with no sideways pull on it. Also check for any debris on the fitting on pipe and tank which might be preventing a seal. A bit of metal swarf, dirt etc. The Kunifer (cupronickel) fuel pipes need to be quite a lot tighter than the copper ones as the metal is harder and not so malleable, same with brake pipes.
Good luck. I also have a 1969 convertible (G) by the way. Last year of convertible production which ended in June 1969. What month was yours made? Mine was built in March.
Stephen
1969 1098cc Convertible “Xavier” which I have owned since 1989.
Stephen
Stephen
-
stuffedpike20
- Minor Addict
- Posts: 888
- Joined: Thu Jul 26, 2018 7:40 pm
- MMOC Member: Yes
Re: Petrol Tank
Yes Stephen, a flare nut spanner. I could not remember the correct name.svenedin wrote: ↑Wed Mar 25, 2026 8:24 pmI am not familiar with the term tube nut spanner. Do you mean a flare nut spanner as used on brake unions?stuffedpike20 wrote: ↑Wed Mar 25, 2026 9:15 am The internal pipe is held in place by a metal tab that is bent over the pipe.
The pipe should not move even if you have moved the tank around a lot.
Maybe the copper pipe from the tank to the carb is not seating properly at the tank end?
I have found that if you do not use a tube nut spanner on the pipe to tank union, the union distorts and is hard to do up, or remove.
What I would suggest to the OP is to disconnect the union from the tank and try again. Push the pipe into its seat and hold it firmly against the seat before tightening up the nut. As with plumbing compression fittings around the house (which have caused me much grief on microbore copper plumbing) there must be no strain on the pipe. It must enter its seat absolutely true with no sideways pull on it. Also check for any debris on the fitting on pipe and tank which might be preventing a seal. A bit of metal swarf, dirt etc. The Kunifer (cupronickel) fuel pipes need to be quite a lot tighter than the copper ones as the metal is harder and not so malleable, same with brake pipes.
Good luck. I also have a 1969 convertible (G) by the way. Last year of convertible production which ended in June 1969. What month was yours made? Mine was built in March.
Stephen
I have found in the past that using an open ended spanner can distort the nut and make it a bit oval. Then it becomes hard to remove, or do up tightly.
-
stuffedpike20
- Minor Addict
- Posts: 888
- Joined: Thu Jul 26, 2018 7:40 pm
- MMOC Member: Yes
Re: Petrol Tank
svenedin wrote: ↑Wed Mar 25, 2026 8:24 pmI am not familiar with the term tube nut spanner. Do you mean a flare nut spanner as used on brake unions?stuffedpike20 wrote: ↑Wed Mar 25, 2026 9:15 am The internal pipe is held in place by a metal tab that is bent over the pipe.
The pipe should not move even if you have moved the tank around a lot.
Maybe the copper pipe from the tank to the carb is not seating properly at the tank end?
I have found that if you do not use a tube nut spanner on the pipe to tank union, the union distorts and is hard to do up, or remove.
What I would suggest to the OP is to disconnect the union from the tank and try again. Push the pipe into its seat and hold it firmly against the seat before tightening up the nut. As with plumbing compression fittings around the house (which have caused me much grief on microbore copper plumbing) there must be no strain on the pipe. It must enter its seat absolutely true with no sideways pull on it. Also check for any debris on the fitting on pipe and tank which might be preventing a seal. A bit of metal swarf, dirt etc. The Kunifer (cupronickel) fuel pipes need to be quite a lot tighter than the copper ones as the metal is harder and not so malleable, same with brake pipes.
Good luck. I also have a 1969 convertible (G) by the way. Last year of convertible production which ended in June 1969. What month was yours made? Mine was built in March.
Stephen
Last edited by stuffedpike20 on Fri Mar 27, 2026 5:51 am, edited 1 time in total.
-
stuffedpike20
- Minor Addict
- Posts: 888
- Joined: Thu Jul 26, 2018 7:40 pm
- MMOC Member: Yes
Re: Petrol Tank
Yes Stephen, a flare nut spanner. I forgot the proper name.
I have found in ther past that using an open ended spanner can make the nut a bit oval. Then it is hard to remove, or do up tightly.
I have found in ther past that using an open ended spanner can make the nut a bit oval. Then it is hard to remove, or do up tightly.
-
stuffedpike20
- Minor Addict
- Posts: 888
- Joined: Thu Jul 26, 2018 7:40 pm
- MMOC Member: Yes
Re: Petrol Tank
Yes, a flare nut spanner. I forgot the proper name.
I have found that using an open ended spanner van make the tube nut oval. Then it becomes hard to remove, or do up tightly.
I have found that using an open ended spanner van make the tube nut oval. Then it becomes hard to remove, or do up tightly.
-
stuffedpike20
- Minor Addict
- Posts: 888
- Joined: Thu Jul 26, 2018 7:40 pm
- MMOC Member: Yes
Re: Petrol Tank
Yes, a flare nut spanner. I forgot the proper name.
I have found that using an open ended spanner can make the tube nut oval. Then it becomes hard to remove, or do up tightly.
I have found that using an open ended spanner can make the tube nut oval. Then it becomes hard to remove, or do up tightly.
-
stuffedpike20
- Minor Addict
- Posts: 888
- Joined: Thu Jul 26, 2018 7:40 pm
- MMOC Member: Yes
Re: Petrol Tank
Yes Stephen, I forgot the name of the spanner.
I have found in the past that using an open ended spanner on the union tends to distort it and make it oval. It is then hard to remove the union, or do it up tightly.
I have found in the past that using an open ended spanner on the union tends to distort it and make it oval. It is then hard to remove the union, or do it up tightly.
-
stuffedpike20
- Minor Addict
- Posts: 888
- Joined: Thu Jul 26, 2018 7:40 pm
- MMOC Member: Yes
Re: Petrol Tank
Yes Stephen, I forgot the name of the spanner.
I have found in the past that using an open ended spanner on the union tends to distort it and make it oval. It is then hard to remove the union, or do it up tightly.
I have found in the past that using an open ended spanner on the union tends to distort it and make it oval. It is then hard to remove the union, or do it up tightly.
-
stuffedpike20
- Minor Addict
- Posts: 888
- Joined: Thu Jul 26, 2018 7:40 pm
- MMOC Member: Yes
Re: Petrol Tank
Yes Stephen, I forgot the name of the spanner.
I have found in the past that using an open ended spanner on the union tends to distort it and make it oval. It is then hard to remove the union, or do it up tightly.
I have found in the past that using an open ended spanner on the union tends to distort it and make it oval. It is then hard to remove the union, or do it up tightly.
-
stuffedpike20
- Minor Addict
- Posts: 888
- Joined: Thu Jul 26, 2018 7:40 pm
- MMOC Member: Yes
Re: Petrol Tank
Yes Stephen, I forgot the name of the spanner.
I have found in the past that using an open ended spanner on the union tends to distort it and make it oval. It is then hard to remove the union, or do it up tightly.
I have found in the past that using an open ended spanner on the union tends to distort it and make it oval. It is then hard to remove the union, or do it up tightly.
-
stuffedpike20
- Minor Addict
- Posts: 888
- Joined: Thu Jul 26, 2018 7:40 pm
- MMOC Member: Yes
Re: Petrol Tank
Yes Stephen, I forgot the name of the spanner.
I have found in the past that using an open ended spanner on the union tends to distort it and make it oval. It is then hard to remove the union, or do it up tightly.
I have found in the past that using an open ended spanner on the union tends to distort it and make it oval. It is then hard to remove the union, or do it up tightly.
- svenedin
- Minor Legend
- Posts: 4741
- Joined: Fri Aug 29, 2014 9:27 am
- Location: Surrey
- MMOC Member: Yes
Re: Petrol Tank
Very sensible! Good idea.stuffedpike20 wrote: ↑Thu Mar 26, 2026 5:54 amYes Stephen, a flare nut spanner. I could not remember the correct name.svenedin wrote: ↑Wed Mar 25, 2026 8:24 pmI am not familiar with the term tube nut spanner. Do you mean a flare nut spanner as used on brake unions?stuffedpike20 wrote: ↑Wed Mar 25, 2026 9:15 am The internal pipe is held in place by a metal tab that is bent over the pipe.
The pipe should not move even if you have moved the tank around a lot.
Maybe the copper pipe from the tank to the carb is not seating properly at the tank end?
I have found that if you do not use a tube nut spanner on the pipe to tank union, the union distorts and is hard to do up, or remove.
What I would suggest to the OP is to disconnect the union from the tank and try again. Push the pipe into its seat and hold it firmly against the seat before tightening up the nut. As with plumbing compression fittings around the house (which have caused me much grief on microbore copper plumbing) there must be no strain on the pipe. It must enter its seat absolutely true with no sideways pull on it. Also check for any debris on the fitting on pipe and tank which might be preventing a seal. A bit of metal swarf, dirt etc. The Kunifer (cupronickel) fuel pipes need to be quite a lot tighter than the copper ones as the metal is harder and not so malleable, same with brake pipes.
Good luck. I also have a 1969 convertible (G) by the way. Last year of convertible production which ended in June 1969. What month was yours made? Mine was built in March.
Stephen![]()
I have found in the past that using an open ended spanner can distort the nut and make it a bit oval. Then it becomes hard to remove, or do up tightly.
Stephen
1969 1098cc Convertible “Xavier” which I have owned since 1989.
Stephen
Stephen
-
stuffedpike20
- Minor Addict
- Posts: 888
- Joined: Thu Jul 26, 2018 7:40 pm
- MMOC Member: Yes
Re: Petrol Tank
As you can see....I tried to reply a few times yesterday, but the site was all over the place!
Obviously it's all gone on today.
Obviously it's all gone on today.
Re: Petrol Tank
Hmmm
Here is the hole and
I have these bits to go back onto the tank which makes me believe the old tank has been in and out before!

The fuel pipe has an olive on it which does form a tight seal when inserted into the union in top of picture and done up tightly using nut in middle of picture. However I doubt whether when those are then inserted into the hole a good seal is made onto what is on the inside of that union in the tank. Am I missing something here as these bits came off the old tank and worked fine.
Oh and here’s the bulkhead plate to try and answer the what month question as I don’t have a clue on that sorry.
![Image]()
Here is the hole and
I have these bits to go back onto the tank which makes me believe the old tank has been in and out before!

The fuel pipe has an olive on it which does form a tight seal when inserted into the union in top of picture and done up tightly using nut in middle of picture. However I doubt whether when those are then inserted into the hole a good seal is made onto what is on the inside of that union in the tank. Am I missing something here as these bits came off the old tank and worked fine.
Oh and here’s the bulkhead plate to try and answer the what month question as I don’t have a clue on that sorry.
- Attachments
-
- IMG_2585.jpeg (3.43 MiB) Viewed 4516 times
-
- IMG_2603.jpeg (1.97 MiB) Viewed 4516 times
-
- IMG_2604.jpeg (3.07 MiB) Viewed 4516 times
- svenedin
- Minor Legend
- Posts: 4741
- Joined: Fri Aug 29, 2014 9:27 am
- Location: Surrey
- MMOC Member: Yes
Re: Petrol Tank
I don't have a reference list of car numbers against build dates but what I can say from your car number as opposed to mine is it suggests that your car is right at the very end of production, possibly even the last month of convertible production which is June 1969. If you look carefully at the car number you will see there is a lightly embossed "M" at the very end which signifies the car was made at Cowley.
Regarding the fuel pipe, have a look at this new one on the ESM website which might help identify the connectors: https://www.morrisminorspares.com/fuel- ... mp-p830609
It looks to me like first the top union in your picture is secured to the tank and then the part with the pipe on it is attached. I have had the connectors weep at the pump end and I just used some Permatex No 3 aviation sealant (which is designed for fuel). The part of yours that has a thread either end is going to have to seal against a washer surely if it isn't a tapered thread (presumably a fibre washer like at the pump end)? Or maybe it is a tapered thread on one end?
If it is a washer missing I'm not quite sure whether it will be AUA1442 or AUA1405. Both of these washers are used at the pump end for similar connectors (see parts diagram https://sucarb.co.uk/su-fuel-pumps-spar ... c-diagrams) I think it's AUA1442
Stephen
Regarding the fuel pipe, have a look at this new one on the ESM website which might help identify the connectors: https://www.morrisminorspares.com/fuel- ... mp-p830609
It looks to me like first the top union in your picture is secured to the tank and then the part with the pipe on it is attached. I have had the connectors weep at the pump end and I just used some Permatex No 3 aviation sealant (which is designed for fuel). The part of yours that has a thread either end is going to have to seal against a washer surely if it isn't a tapered thread (presumably a fibre washer like at the pump end)? Or maybe it is a tapered thread on one end?
If it is a washer missing I'm not quite sure whether it will be AUA1442 or AUA1405. Both of these washers are used at the pump end for similar connectors (see parts diagram https://sucarb.co.uk/su-fuel-pumps-spar ... c-diagrams) I think it's AUA1442
Stephen
1969 1098cc Convertible “Xavier” which I have owned since 1989.
Stephen
Stephen
Re: Petrol Tank
These are the connectors you need, The nipple is soldered on the end of the fuel pipe. They are available on eBay. Image from Moss.
Fuel Tank Pipe Nut and Nipple: Part No: ACA 5128 & ACA5129
Fuel Tank Pipe Nut and Nipple: Part No: ACA 5128 & ACA5129
- Attachments
-
- Screenshot 2026-04-09 095927.jpg (12.83 KiB) Viewed 4445 times
Re: Petrol Tank
Thanks both Stephen and MM1949.
Unfortunately the picture from ESM shows the tank end covered with the black plastic protector.
I’m pretty comfortable with the pipe connecting into that union - it’s when that connects into the tank that I believe the problem lies.
Possible solution is the washer you suggest Stephen AUA1405 as that seems to be the closest match to the unions/connectors I have on my bench in front of me.
Plus of course a healthy dose of sealant!
Unfortunately the picture from ESM shows the tank end covered with the black plastic protector.
I’m pretty comfortable with the pipe connecting into that union - it’s when that connects into the tank that I believe the problem lies.
Possible solution is the washer you suggest Stephen AUA1405 as that seems to be the closest match to the unions/connectors I have on my bench in front of me.
Plus of course a healthy dose of sealant!