Help Needed : Leak From Fuel Filter M750

motomartin11 · 29-05-2022, 06:58 AM

I've just fitted a re-sprayed black tank to my bike with new aftermarket fuel lines and filter. The bike has passed its MOT and I thought I was ready for the riding season. However I can't get the fuel filter / fuel pipe to seal and the constant drip / smell of fuel is driving to distraction! Any ideas please? Am I best to call MR and order up a new OE filter ,pipes and clips? The clips I'm using are used and I've no idea if they are the correct type or size.

350TSS · 29-05-2022, 07:34 AM

If you are using Jubilee hose clamps to seal the petrol pipes they have to be the right size in that the radius beneath the tightening screw must be an exact match for the OD of the petrol pipe, if not then the clamp when tightened distorts the rubber hose and prevents it sealing to the internal pipe. If you can get them the spring clip type are better as they apply an even pressure to the rubber pipe, they are also re-usable, downside is the tangs are ugly and in confined places can scratch the back of your hand.

Albie · 29-05-2022, 10:31 AM

Dont use jubilee clips on fuel lines. 1 they are bulky. 2 they cut into the pipe and 3 they dont always keep round.
Use petrol pipe clips the correct size.

Mr Gazza · 29-05-2022, 12:13 PM

I would recommend getting the right filter and hoses, and obviously endorse Moto Rapido as the best supplier.

On those models with Vacuum taps, pumps, and external filter, the fuel hoses are quite specific. There is one in particular that is moulded and reduces in size from one end to the other. so if you are using generic hose I reckon that might be where the problem is. Where the spigot diameter steps down?

Flip posted up a picture of the spares catalogue with all the hoses on, which would explain it beautifully, but I can't find it.. Sorry.

Mr Gazza · 29-05-2022, 02:03 PM

I found a thread with the pipe diagram.
http://www.ukmonster.co.uk/monster/s...ad.php?t=59503
Look at post 18... Might be familiar?

motomartin11 · 29-05-2022, 06:38 PM

Thanks to all.
Oops Gary, yes I had a senior moment and quite forgot about some of the replies to my previous thread but it was nearly 9 months ago.
I'm not using jubilee clips though if I was royalist maybe I should this week?
Going to order the 2 small fuel pipes from the tank to the filter and filter to the tap and the clips. The clips I'm using are the ones that can be re-used but I question the quality of the ones I've used. As has been pointed out I hope it's the using of generic pipe as opposed to the moulded OE type that's been my downfall and I was given the "heads up" in my earlier thread.
I'll call Luke and Craig tomorrow.

motomartin11 · 30-05-2022, 05:30 PM

MR only have some of the parts I need. The others are NLA. I think they have the fuel hose (which is leaking) and most of the clips although I appreciate after-market types can be used. I ordered an OE fuel filter as well just in case. Some of the parts are having to be ordered from Italy. I may have to use one of the old fuel hoses which are OE types but a little age hardened but not split as far as I can tell.

jamminbmx · 02-06-2022, 06:24 AM

I had exactly the same issue on my M600. Ended up using a 6mm line from tank to a straight filter. Then an 8mm line from filter to fuel tap. The filter was stepped to accept both sizes. It was not elegant but it does work. I'm going to buy the OEM parts though when I next order stuff. The original set up is much neater.

motomartin11 · 02-06-2022, 06:37 PM

Still waiting for my order to come from Moto Rapido. Getting frustrated that I can't ride my Monster now summer has eventually arrived! Luckily I do have other bikes I can use but none is as enthralling as my Monster.

motomartin11 · 05-06-2022, 10:48 AM

Right, I've received my parts order from MR .I'm having to re-use one of the old OE fuel pipes (the one from the filter to the tap which seems to be OK) but have a new one from the tank outlet to the filter. As it's been 9 months since I stripped down these parts I'm struggling to work out the orientation of the filter and pipes. I know the filter has a spring steel securing ring which goes around the body of the filter and screws to a thread on the underside of the tank but I can't work out what goes where. The Haynes manual doesn't really help nor does having to work upside down with the empty fuel tank propped up on a piece of timber. Can anyone point me in the right direction please?

Flip · 05-06-2022, 11:23 AM

Fuel filter orientation is as per the schematic for the pipework that Mr G kindly referenced from a post I put up some time ago.

But here it is again if you can't find it:

If the bike has been stood around for as long as you say, my advice would be to also look at the vacuum fuel pump as the insides of mine had definitely seen better days before Ethanol took it's toll but luckily it's rebuildable.

Also worth a look is the vaccum fuel tap, which unfortunately isn't rebuildable but doesn't cost a fortune either- about £35 I am guessing.

Going on from those if you haven't done so already, would be to replace both vacuum pipes from the inlet manifolds as any air getting in will stop things operating as they should.

Like I said before, I did the lot when I went through mine as it was getting on for twenty years old and I didn't want to keep having issues- so far I haven't and so the time and money spent back then was all worth it not to keep getting interrupted with similar issues.

motomartin11 · 05-06-2022, 12:00 PM

Yes thanks for posting. I've been searching this forum for similar posts.

Fortunately the PO Nick (Enbee) rebuilt the vacuum fuel pump with a Mikuni kit just before I got the bike so that should be OK.

He also provided me with another tap which I've fitted. I may however look at getting a new OE or aftermarket one.

I think I will look at replacing the vacuum pipes (and perhaps the tap) over the winter when I drain the fuel system down again.

I'll get back in the workshop now and try to figure out what goes where following your post.

motomartin11 · 05-06-2022, 01:08 PM

All sorted thanks. Now the fuel pipes are in their correct orientation and the clamps are tightened. Just got to put fuel in the tank and start it up.

motomartin11 · 05-06-2022, 03:30 PM

Oh no....can't now get the fuel pipe from the filter to the tap to seal-or the tap itself is leaking, I can't tell which .The fuel pipe is the old one which is NLA so I'll have to use an aftermarket one. The original is as you would expect hard and think that may be the problem as it's too inflexible to seal around the tap joint.I may have to bite the bullet and order a new tap from MR.

Mr Gazza · 05-06-2022, 03:42 PM

I once heard that you can soften old rubber by gently heating it in White vinegar.
I tried it once with a seal many years ago, but let it boil dry, so I can't vouch for whether it works or not if done properly.
Might be worth a try if it's no good anyway?

29-05-2022, 06:58 AM	#1
motomartin11 Registered User Join Date: Sep 2010 Location: stourbridge Bike: M750 Posts: 352	Help Needed : Leak From Fuel Filter M750 I've just fitted a re-sprayed black tank to my bike with new aftermarket fuel lines and filter. The bike has passed its MOT and I thought I was ready for the riding season. However I can't get the fuel filter / fuel pipe to seal and the constant drip / smell of fuel is driving to distraction! Any ideas please? Am I best to call MR and order up a new OE filter ,pipes and clips? The clips I'm using are used and I've no idea if they are the correct type or size.

29-05-2022, 07:34 AM	#2
350TSS Too much time on my hands member Join Date: Jan 2013 Location: Shipbourne Bike: M900 Posts: 1,419	If you are using Jubilee hose clamps to seal the petrol pipes they have to be the right size in that the radius beneath the tightening screw must be an exact match for the OD of the petrol pipe, if not then the clamp when tightened distorts the rubber hose and prevents it sealing to the internal pipe. If you can get them the spring clip type are better as they apply an even pressure to the rubber pipe, they are also re-usable, downside is the tangs are ugly and in confined places can scratch the back of your hand. Last edited by 350TSS; 29-05-2022 at 07:36 AM..

29-05-2022, 10:31 AM	#3
Albie Fanactical volunteer Join Date: Oct 2003 Location: Kent Bike: M900 Posts: 9,030	Dont use jubilee clips on fuel lines. 1 they are bulky. 2 they cut into the pipe and 3 they dont always keep round. Use petrol pipe clips the correct size. __________________ http://albies93m900.blogspot.co.uk/

29-05-2022, 12:13 PM	#4
Mr Gazza Lord of the Rings Join Date: May 2013 Location: Norwich Bike: M900sie Posts: 5,795	I would recommend getting the right filter and hoses, and obviously endorse Moto Rapido as the best supplier. On those models with Vacuum taps, pumps, and external filter, the fuel hoses are quite specific. There is one in particular that is moulded and reduces in size from one end to the other. so if you are using generic hose I reckon that might be where the problem is. Where the spigot diameter steps down? Flip posted up a picture of the spares catalogue with all the hoses on, which would explain it beautifully, but I can't find it.. Sorry. __________________

29-05-2022, 02:03 PM	#5
Mr Gazza Lord of the Rings Join Date: May 2013 Location: Norwich Bike: M900sie Posts: 5,795	I found a thread with the pipe diagram. http://www.ukmonster.co.uk/monster/s...ad.php?t=59503 Look at post 18... Might be familiar? __________________

29-05-2022, 06:38 PM	#6
motomartin11 Registered User Join Date: Sep 2010 Location: stourbridge Bike: M750 Posts: 352	Thanks to all. Oops Gary, yes I had a senior moment and quite forgot about some of the replies to my previous thread but it was nearly 9 months ago. I'm not using jubilee clips though if I was royalist maybe I should this week? Going to order the 2 small fuel pipes from the tank to the filter and filter to the tap and the clips. The clips I'm using are the ones that can be re-used but I question the quality of the ones I've used. As has been pointed out I hope it's the using of generic pipe as opposed to the moulded OE type that's been my downfall and I was given the "heads up" in my earlier thread. I'll call Luke and Craig tomorrow.

30-05-2022, 05:30 PM	#7
motomartin11 Registered User Join Date: Sep 2010 Location: stourbridge Bike: M750 Posts: 352	MR only have some of the parts I need. The others are NLA. I think they have the fuel hose (which is leaking) and most of the clips although I appreciate after-market types can be used. I ordered an OE fuel filter as well just in case. Some of the parts are having to be ordered from Italy. I may have to use one of the old fuel hoses which are OE types but a little age hardened but not split as far as I can tell.

02-06-2022, 06:24 AM	#8
jamminbmx Registered User Join Date: Mar 2016 Location: oxford Bike: M600 Posts: 131	I had exactly the same issue on my M600. Ended up using a 6mm line from tank to a straight filter. Then an 8mm line from filter to fuel tap. The filter was stepped to accept both sizes. It was not elegant but it does work. I'm going to buy the OEM parts though when I next order stuff. The original set up is much neater.

02-06-2022, 06:37 PM	#9
motomartin11 Registered User Join Date: Sep 2010 Location: stourbridge Bike: M750 Posts: 352	Still waiting for my order to come from Moto Rapido. Getting frustrated that I can't ride my Monster now summer has eventually arrived! Luckily I do have other bikes I can use but none is as enthralling as my Monster.

05-06-2022, 10:48 AM	#10
motomartin11 Registered User Join Date: Sep 2010 Location: stourbridge Bike: M750 Posts: 352	Right, I've received my parts order from MR .I'm having to re-use one of the old OE fuel pipes (the one from the filter to the tap which seems to be OK) but have a new one from the tank outlet to the filter. As it's been 9 months since I stripped down these parts I'm struggling to work out the orientation of the filter and pipes. I know the filter has a spring steel securing ring which goes around the body of the filter and screws to a thread on the underside of the tank but I can't work out what goes where. The Haynes manual doesn't really help nor does having to work upside down with the empty fuel tank propped up on a piece of timber. Can anyone point me in the right direction please?

05-06-2022, 11:23 AM	#11
Flip Registered User Join Date: Mar 2010 Location: Beachtown Bike: M900 Posts: 2,188	Fuel filter orientation is as per the schematic for the pipework that Mr G kindly referenced from a post I put up some time ago. But here it is again if you can't find it: If the bike has been stood around for as long as you say, my advice would be to also look at the vacuum fuel pump as the insides of mine had definitely seen better days before Ethanol took it's toll but luckily it's rebuildable. Also worth a look is the vaccum fuel tap, which unfortunately isn't rebuildable but doesn't cost a fortune either- about £35 I am guessing. Going on from those if you haven't done so already, would be to replace both vacuum pipes from the inlet manifolds as any air getting in will stop things operating as they should. Like I said before, I did the lot when I went through mine as it was getting on for twenty years old and I didn't want to keep having issues- so far I haven't and so the time and money spent back then was all worth it not to keep getting interrupted with similar issues. __________________ You're perfect, yes, it's true- But without me you're only you!

05-06-2022, 12:00 PM	#12
motomartin11 Registered User Join Date: Sep 2010 Location: stourbridge Bike: M750 Posts: 352	Yes thanks for posting. I've been searching this forum for similar posts. Fortunately the PO Nick (Enbee) rebuilt the vacuum fuel pump with a Mikuni kit just before I got the bike so that should be OK. He also provided me with another tap which I've fitted. I may however look at getting a new OE or aftermarket one. I think I will look at replacing the vacuum pipes (and perhaps the tap) over the winter when I drain the fuel system down again. I'll get back in the workshop now and try to figure out what goes where following your post.

05-06-2022, 01:08 PM	#13
motomartin11 Registered User Join Date: Sep 2010 Location: stourbridge Bike: M750 Posts: 352	All sorted thanks. Now the fuel pipes are in their correct orientation and the clamps are tightened. Just got to put fuel in the tank and start it up.

05-06-2022, 03:30 PM	#14
motomartin11 Registered User Join Date: Sep 2010 Location: stourbridge Bike: M750 Posts: 352	Oh no....can't now get the fuel pipe from the filter to the tap to seal-or the tap itself is leaking, I can't tell which .The fuel pipe is the old one which is NLA so I'll have to use an aftermarket one. The original is as you would expect hard and think that may be the problem as it's too inflexible to seal around the tap joint.I may have to bite the bullet and order a new tap from MR.

05-06-2022, 03:42 PM	#15
Mr Gazza Lord of the Rings Join Date: May 2013 Location: Norwich Bike: M900sie Posts: 5,795	I once heard that you can soften old rubber by gently heating it in White vinegar. I tried it once with a seal many years ago, but let it boil dry, so I can't vouch for whether it works or not if done properly. Might be worth a try if it's no good anyway? __________________