'96 M750 Stupid Question Fuel Tap

motomartin11 · 19-09-2021, 03:44 PM

I'm in the process of draining down my fuel tank as I have a leak to fix. I've accessed the fuel tap which is situated directly under the hinge at the back but I can't for the life of me see any means of turning the off fuel at the tap? Am I missing something really obvious? I've looked online and searched on here but can't see anything to help.

Jam911 · 19-09-2021, 04:10 PM

After suffering two massive fuel leaks over the past few months, I am pretty sure you can't turn it off

manwithredbike · 19-09-2021, 04:39 PM

It's a vacuum tap. Fuel shouldn't flow through it when the engine is stopped.
Mine was faulty and i replaced it with a spurious brand tap. I also fitted an in-line tap on the fuel line just as a sure way to lock of the flow if needed.

motomartin11 · 19-09-2021, 04:49 PM

Thank you.
It could be faulty then as fuel starts dribbling when I undo one of the pipes.
I don't trust these vacuum taps-my old KH500 had one and I remember spending a Christmas eve desperately draining the tank after it leaked. Think I will replace with one you can manually turn on and off for peace of mind. Anyone recommend something that will do the job please?

manwithredbike · 19-09-2021, 06:30 PM

fuel should only dribble from the pipe that comes off the tank outlet.
It's a while ago now so i can't remember the exact details but I replaced mine with a cheap vacuum tap that cost less than a tenner online. The Ducati replacement was something like 70 quid or so I think.
I also fitted a simple universal in-line fuel tap down stream of the vacuum tap where i can reach it easily. I just searched online, think I ended up getting both on ebay.

motomartin11 · 19-09-2021, 06:33 PM

Thanks. What confused me is the Haynes manual says before removing the tank to turn off the fuel!

utopia · 19-09-2021, 07:00 PM

Earlier monsters had a manual fuel tap.
Not sure exactly when they changed over but if your '96 750 has a vacuum tap I'd guess its one of the first to have one.
Or else a previous owner has swapped over.

motomartin11 · 19-09-2021, 07:26 PM

Quote:

Originally Posted by utopia

Earlier monsters had a manual fuel tap.
Not sure exactly when they changed over but if your '96 750 has a vacuum tap I'd guess its one of the first to have one.
Or else a previous owner has swapped over.

Thank you-yes I thought it should have been a manual one from my limited investigations.

Albie · 20-09-2021, 07:01 AM

Quote:

Originally Posted by motomartin11

Thank you-yes I thought it should have been a manual one from my limited investigations.

Early ones had the knurled round tap. Rotate it to shut off like a tap. Later had the black plastic switch one in the frame space above the rear brake pedal clutch side.

enbee23 · 20-09-2021, 08:21 AM

I'm pretty sure the vacuum tap is correct for the bike. There would have been mounting lugs on the frame if it had a manual tap from the factory which are not there.

Nickj · 20-09-2021, 03:27 PM

Quote:

Originally Posted by motomartin11

Thank you.
It could be faulty then as fuel starts dribbling when I undo one of the pipes.
I don't trust these vacuum taps-my old KH500 had one and I remember spending a Christmas eve desperately draining the tank after it leaked. Think I will replace with one you can manually turn on and off for peace of mind. Anyone recommend something that will do the job please?

Lucky .. I remember finding the crank cases full of fuel on a KH I'd got for cheap that had been standing for 18 months or so. It was pre ethanol days and after it was drained it was very clean but very dry so a bit good and a bit more bad really

Flip · 20-09-2021, 04:27 PM

I’ve never had the vacuum tap leak (touch wood) on my 1997 900 but I did replace it when it was about eighteen years old as part of a fuel system refresh I did to combat the effects of modern fuel (the fuel pump diagrams were completely shot) as my bike began suffering from a vapour lock in very hot weather/heavy traffic conditions that caused it to cut out due to fuel starvation.

I Know people have changed them in favour of a manual tap but at less than thirty quid (that’s some price increase if they’re £70 now) from Moto Rapido and given the original had been reliable I didn’t see much point in deviating from that set up and I’ve had no issues since no matter how hot it’s got or how or where it’s ridden.

It’s this fella you’re talking about yes?

Remember one pipe (not fitted in the photo) is the feed from the fuel tank so fuel will flow from there as you undo it, then the centre is the supply to the vacuum fuel pump and the last, smaller diameter one on the side is the vacuum pipe from the cylinder inlet manifold.

motomartin11 · 20-09-2021, 05:00 PM

Quote:

Originally Posted by Flip

I’ve never had the vacuum tap leak (touch wood) on my 1997 900 but I did replace it when it was about eighteen years old as part of a fuel system refresh I did to combat the effects of modern fuel (the fuel pump diagrams were completely shot) as my bike began suffering from a vapour lock in very hot weather/heavy traffic conditions that caused it to cut out due to fuel starvation.

I Know people have changed them in favour of a manual tap but at less than thirty quid (that’s some price increase if they’re £70 now) from Moto Rapido and given the original had been reliable I didn’t see much point in deviating from that set up and I’ve had no issues since no matter how hot it’s got or how or where it’s ridden.

It’s this fella you’re talking about yes?

Remember one pipe (not fitted in the photo) is the feed from the fuel tank so fuel will flow from there as you undo it, then the centre is the supply to the vacuum fuel pump and the last, smaller diameter one on the side is the vacuum pipe from the cylinder inlet manifold.

Yes that's the one.
Looks a bit like a shrunken horn. I take it this is the type you can't turn off?
The fuel pump was serviced by the PO Nick (enbee23).

motomartin11 · 20-09-2021, 05:04 PM

Quote:

Originally Posted by Nickj

Lucky .. I remember finding the crank cases full of fuel on a KH I'd got for cheap that had been standing for 18 months or so. It was pre ethanol days and after it was drained it was very clean but very dry so a bit good and a bit more bad really

Yes even the old fuel used to dry up and crystallise in the carbs if left long enough as well.

motomartin11 · 20-09-2021, 05:10 PM

Quote:

Originally Posted by enbee23

I'm pretty sure the vacuum tap is correct for the bike. There would have been mounting lugs on the frame if it had a manual tap from the factory which are not there.

Thanks Nick. It's been 12 months since I bought the bike and I have to say I'm still very pleased I did. I don't think I've ever owned a bike with more character than this!

19-09-2021, 03:44 PM	#1
motomartin11 Registered User Join Date: Sep 2010 Location: stourbridge Bike: M750 Posts: 352	'96 M750 Stupid Question Fuel Tap I'm in the process of draining down my fuel tank as I have a leak to fix. I've accessed the fuel tap which is situated directly under the hinge at the back but I can't for the life of me see any means of turning the off fuel at the tap? Am I missing something really obvious? I've looked online and searched on here but can't see anything to help.

19-09-2021, 04:10 PM	#2
Jam911 Registered User Join Date: Jun 2021 Location: Stratford Upon Avon Bike: Multiple Monsters Posts: 288	After suffering two massive fuel leaks over the past few months, I am pretty sure you can't turn it off Last edited by Jam911; 19-09-2021 at 04:12 PM..

19-09-2021, 04:39 PM	#3
manwithredbike aka Phil Join Date: Nov 2005 Location: derry Bike: M900 Posts: 376	It's a vacuum tap. Fuel shouldn't flow through it when the engine is stopped. Mine was faulty and i replaced it with a spurious brand tap. I also fitted an in-line tap on the fuel line just as a sure way to lock of the flow if needed. __________________ .. ~

19-09-2021, 06:30 PM	#5
manwithredbike aka Phil Join Date: Nov 2005 Location: derry Bike: M900 Posts: 376	fuel should only dribble from the pipe that comes off the tank outlet. It's a while ago now so i can't remember the exact details but I replaced mine with a cheap vacuum tap that cost less than a tenner online. The Ducati replacement was something like 70 quid or so I think. I also fitted a simple universal in-line fuel tap down stream of the vacuum tap where i can reach it easily. I just searched online, think I ended up getting both on ebay. __________________ .. ~

20-09-2021, 04:27 PM	#12
Flip Registered User Join Date: Mar 2010 Location: Beachtown Bike: M900 Posts: 2,188	I’ve never had the vacuum tap leak (touch wood) on my 1997 900 but I did replace it when it was about eighteen years old as part of a fuel system refresh I did to combat the effects of modern fuel (the fuel pump diagrams were completely shot) as my bike began suffering from a vapour lock in very hot weather/heavy traffic conditions that caused it to cut out due to fuel starvation. I Know people have changed them in favour of a manual tap but at less than thirty quid (that’s some price increase if they’re £70 now) from Moto Rapido and given the original had been reliable I didn’t see much point in deviating from that set up and I’ve had no issues since no matter how hot it’s got or how or where it’s ridden. It’s this fella you’re talking about yes? Remember one pipe (not fitted in the photo) is the feed from the fuel tank so fuel will flow from there as you undo it, then the centre is the supply to the vacuum fuel pump and the last, smaller diameter one on the side is the vacuum pipe from the cylinder inlet manifold. __________________ You're perfect, yes, it's true- But without me you're only you! Last edited by Flip; 20-09-2021 at 04:38 PM..

19-09-2021, 04:49 PM	#4
motomartin11 Registered User Join Date: Sep 2010 Location: stourbridge Bike: M750 Posts: 352	Thank you. It could be faulty then as fuel starts dribbling when I undo one of the pipes. I don't trust these vacuum taps-my old KH500 had one and I remember spending a Christmas eve desperately draining the tank after it leaked. Think I will replace with one you can manually turn on and off for peace of mind. Anyone recommend something that will do the job please?

19-09-2021, 06:33 PM	#6
motomartin11 Registered User Join Date: Sep 2010 Location: stourbridge Bike: M750 Posts: 352	Thanks. What confused me is the Haynes manual says before removing the tank to turn off the fuel!

19-09-2021, 07:00 PM	#7
utopia No turn left unstoned Join Date: Jun 2010 Location: leicester Bike: M750 Posts: 4,545	Earlier monsters had a manual fuel tap. Not sure exactly when they changed over but if your '96 750 has a vacuum tap I'd guess its one of the first to have one. Or else a previous owner has swapped over.

20-09-2021, 08:21 AM	#10
enbee23 Registered User Join Date: Sep 2020 Location: Nairn Bike: S4r Posts: 99	I'm pretty sure the vacuum tap is correct for the bike. There would have been mounting lugs on the frame if it had a manual tap from the factory which are not there.