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Identifying a fuel leak?

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Falco
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FredTheHorse



Joined: 26 Nov 2015
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PostPosted: 19:28 - 11 Jan 2017    Post subject: Identifying a fuel leak? Reply with quote

And so it begins! Neutral

Noticed some fuel leaking onto/around tap when starting this morning. While cleaning it, it seemed to resolve itself.

Rode it 25 miles and left it for a couple of hours and there was nothing under the bike when I got back. Struggled to start needing choke and throttle despite short period of inactivity. Once going it was fine except for a tendency to idle too low and stall at the start of the journey (bigger bikes take longer to warm up? Not sure if relevant).

However I had to refuel before coming home despite having filled up yesterday and covering only 75 miles since (the gauge was firmly in the red and the tank was fairly empty).

Noticed a petrol smell a couple of times when riding and around the bike generally. Taken the tank off and the tap seems fine so I am a bit of a loss now, what are the likely culprits? Worth running with the tank off to see if its the carbs that are leaking?
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mudcow007
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PostPosted: 19:43 - 11 Jan 2017    Post subject: Reply with quote

is a float sticking open an its flowing out the carbs?

fuel evaporates so might not see a puddle

check oil level - as you may have a crankcase full of oily petrol

what bike?
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Falco
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PostPosted: 19:56 - 11 Jan 2017    Post subject: Reply with quote

mudcow007 wrote:
is a float sticking open an its flowing out the carbs?

fuel evaporates so might not see a puddle


Possibly, when it leaked, I noticed it on the tap, I don't recall any on the carbs. How would I check? Does the carburetor need to come out to check this?

mudcow007 wrote:
check oil level - as you may have a crankcase full of oily petrol

what bike?


Via the dipstick? Oil level looked high this morning.

Sorry, must have edited out the make when removing extraneous information from the post, its an ER5.

EDIT: just realised I don't have a dipstick....
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mudcow007
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PostPosted: 20:13 - 11 Jan 2017    Post subject: Reply with quote

have you got a centre stand? if so stick it on centre stand take a note of level, leave it a while with fuel in check later.

Personally if in doubt i would dump the oil an change it now - for the sake of a few quid its cheaper than an engine

Maybe a thought to whip the tank off so you can see underneath/ tap fully?

I know my Bandit had a pin hole (rust) in the tank under the seat which was barely noticeable but stunk of fuel


http://justkdx.dirtrider.net/images/needle.gif

thats what would be causing the leak (if its through the carbs)
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Falco
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FredTheHorse



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PostPosted: 20:56 - 11 Jan 2017    Post subject: Reply with quote

mudcow007 wrote:
have you got a centre stand? if so stick it on centre stand take a note of level, leave it a while with fuel in check later.

Personally if in doubt i would dump the oil an change it now - for the sake of a few quid its cheaper than an engine

Maybe a thought to whip the tank off so you can see underneath/ tap fully?

I know my Bandit had a pin hole (rust) in the tank under the seat which was barely noticeable but stunk of fuel


http://justkdx.dirtrider.net/images/needle.gif

thats what would be causing the leak (if its through the carbs)


It does have a centre stand, but I can't check the oil level as its over the top of the sight glass...

It's due an oil change anyway, guess it's going to be a cold one.

The tank is off, the tap looks fine, clean and dry even after almost 2 hours off the bike, thought it might be the hoses but apparently not.

No holes in the tank that I can see. Looks like carbs are the most likely culprit?
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Tawny
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PostPosted: 21:23 - 11 Jan 2017    Post subject: Reply with quote

It's most likely to be either the hose(s) around the fuel tap or a failed fuel tap.

Before you do anything, remove the oil filler cap and sniff it immediately. If it smells of petrol, then the bike has been dumping petrol into the oil sump (this will have been caused by a failed fuel tap eventually causing the carb float to fail or stick open). If it doesn't smell of petrol and the oil level is fine, that's good. If it smells of petrol and the sump is overfull, don't start the bike until this issue has been fixed.

Next, you will note that there are several hoses going to the vacuum fuel tap. Imagine you wanted to access the engine. You would need to remove the fuel tank. The proper way is to disconnect the vacuum hose and the fuel hose going to the carbs, and then twist the fuel tap so that it pulls out along with the tank. This is very awkward, so, unfortunately, there's also an improper shortcut to removing the fuel tank, and that's to pop off the 2 hoses going from the tank to the fuel tap. Do this more than once or twice, and the hoses fail... It's quite likely that this has happened. Look very closely and you might be able to see a crack in a hose at the top of the fuel tap, where it connects to the fuel tap. If so, there's your problem.

It's a good idea to replace all your hoses anyway, as they're cheap. If the hose is leaking fuel, a cheapskate easy fix is to remove the hoses attaching to the top of the fuel tap (which go to the petrol tank) from the fuel tap, like the previous owner probably did (have a clamp ready as you will get splashed in the face), then cut an inch off the end of the hose with a razor blade, then press it back down hard and reattach it to the fuel tap.

If it isn't a hose, and you've got a fuel tap problem, let us know.
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cresad
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PostPosted: 21:31 - 11 Jan 2017    Post subject: Reply with quote

Hi

I had a tank that leaked on a cg clone that turned out to be coming from the fuel level sender unit under the tank , I'm not saying that's where yours is but I noticed a strong fuel smell regularly and it did leave a stain on the floor ( not wet ) when left over night.
I also found that fuel was running down the inside of the tank and getting blown onto my left hand side boot , it was worse with a full tank as the weight of the fuel opened the gap more. After rewilding the flange and trying half a dozen different sealing compounds I gave it up as a bad tank and 1 changed the bike and 2 needed to change the tank.

Good luck , Adam
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Falco
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FredTheHorse



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PostPosted: 21:49 - 11 Jan 2017    Post subject: Reply with quote

Tawny wrote:
It's most likely to be either the hose(s) around the fuel tap or a failed fuel tap.

Before you do anything, remove the oil filler cap and sniff it immediately. If it smells of petrol, then the bike has been dumping petrol into the oil sump (this will have been caused by a failed fuel tap eventually causing the carb float to fail or stick open). If it doesn't smell of petrol and the oil level is fine, that's good. If it smells of petrol and the sump is overfull, don't start the bike until this issue has been fixed.


It's hard to tell because everything on the bike smells of petrol (more on that in a moment). Worth checking the carbs anyway, you reckon?
The bike has been ridden like this before I even realised it was in the oil....around 50 miles today, how much damage is that likely to have done?



Tawny wrote:
Next, you will note that there are several hoses going to the vacuum fuel tap. Imagine you wanted to access the engine. You would need to remove the fuel tank. The proper way is to disconnect the vacuum hose and the fuel hose going to the carbs, and then twist the fuel tap so that it pulls out along with the tank. This is very awkward, so, unfortunately, there's also an improper shortcut to removing the fuel tank, and that's to pop off the 2 hoses going from the tank to the fuel tap. Do this more than once or twice, and the hoses fail... It's quite likely that this has happened. Look very closely and you might be able to see a crack in a hose at the top of the fuel tap, where it connects to the fuel tap. If so, there's your problem.

It's a good idea to replace all your hoses anyway, as they're cheap. If the hose is leaking fuel, a cheapskate easy fix is to remove the hoses attaching to the top of the fuel tap (which go to the petrol tank) from the fuel tap, like the previous owner probably did (have a clamp ready as you will get splashed in the face), then cut an inch off the end of the hose with a razor blade, then press it back down hard and reattach it to the fuel tap.

If it isn't a hose, and you've got a fuel tap problem, let us know.



I'll have a look at the hoses tomorrow morning, if this is the culprit, are there any places that list the pipe diameters? I found a similar query but are both the same dimensions?

To say that getting the fuel tap out of the engine frame is awkward is an understatement. That is why the whole bike smells of petrol, (that and I took off one of the pipes going to the tap from the tank like a numpty and got petrol everywhere).

I don't think the tap has failed, at least not in the sense that it is allowing fuel through all the time. The tank has been off the bike for most of the evening and no fuel has come out through the tap once it was disconnected.
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Tawny
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PostPosted: 22:10 - 11 Jan 2017    Post subject: Reply with quote

Falco wrote:
It's hard to tell because everything on the bike smells of petrol (more on that in a moment). Worth checking the carbs anyway, you reckon?


The diagnostic order I would choose would be: first check hoses, then check fuel tap, then check carbs.
The reason for this order is that when the fuel tap goes, the carb may or may not follow. Whereas if the carb has a dodgy or sticking float but your fuel tap is working, this wouldn't make your bike stink of petrol at rest, because petrol wouldn't be flowing into the carb at rest.

If you want to do a quick and dirty check for carbs dumping fuel into the airbox, there should be two overflow pipes going out of the airbox and coming down the right hand side of the bike, near the swingarm. One of them should be stoppered. If you remove the bung and a substance comes out, if it's a few drops of water that's normal, but if it's petrol then yes, you have an overflowing carb.

Quote:
The bike has been ridden like this before I even realised it was in the oil....around 50 miles today, how much damage is that likely to have done?


All we know at this stage is that it stinks of petrol and you suspect it has leaked a lot. On a full tank you should have been able to travel much further.

It's purely hypothetical, but supposing petrol had gone into your sump, it would have done it in a typically large quantity (litres) and thinned out the oil a lot. This can cause catastrophic engine failure very, very quickly. Or massive amounts wear and tear without causing the engine to fail there and then, but shortly thereafter.

However, there's no need to speculate on this. You've just bought the bike so you should have engine oil and a new oil filter available to hand. You'll see or smell if there is petrol in the oil, when you dump the old oil (petrol will make it smell and cause visible emulsion effects, and engine damage will look like silver glitter).

Quote:
I'll have a look at the hoses tomorrow morning, if this is the culprit, are there any places that list the pipe diameters? I found a similar query but are both the same dimensions?


For the fuel hoses, you need petrol-suitable hose, about a metre of it, with a diameter of 8 or 9 mm (EDIT: 6.5mm internal like the other poster said, sounds right). Both of these will be a snug fit over the fuel tap.

Quote:
I don't think the tap has failed, at least not in the sense that it is allowing fuel through all the time. The tank has been off the bike for most of the evening and no fuel has come out through the tap once it was disconnected.


That's good. Check the airbox then, and replace all your hoses. With any luck it's just a cracked hose.
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Falco
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FredTheHorse



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PostPosted: 22:48 - 11 Jan 2017    Post subject: Reply with quote

Tawny wrote:
The diagnostic order I would choose would be: first check hoses, then check fuel tap, then check carbs.
The reason for this order is that when the fuel tap goes, the carb may or may not follow. Whereas if the carb has a dodgy or sticking float but your fuel tap is working, this wouldn't make your bike stink of petrol at rest, because petrol wouldn't be flowing into the carb at rest.

If you want to do a quick and dirty check for carbs dumping fuel into the airbox, there should be two overflow pipes going out of the airbox and coming down the right hand side of the bike, near the swingarm. One of them should be stoppered. If you remove the bung and a substance comes out, if it's a few drops of water that's normal, but if it's petrol then yes, you have an overflowing carb.


Cheers, I've already got the side panels off for the tank, so take the airbox cover off tomorrow and see if there is anything in there as well as the hoses.

Tawny wrote:
All we know at this stage is that it stinks of petrol and you suspect it has leaked a lot. On a full tank you should have been able to travel much further.

It's purely hypothetical, but supposing petrol had gone into your sump, it would have done it in a typically large quantity (litres) and thinned out the oil a lot. This can cause catastrophic engine failure very, very quickly. Or massive amounts wear and tear without causing the engine to fail there and then, but shortly thereafter.

However, there's no need to speculate on this. You've just bought the bike so you should have engine oil and a new oil filter available to hand. You'll see or smell if there is petrol in the oil, when you dump the old oil (petrol will make it smell and cause visible emulsion effects, and engine damage will look like silver glitter).


Shocked Might be well on the way to that. It started to tap/clatter quite noticeably on the way home.... Filter should be turning up tomorrow or friday, oil ready to go. Was planning to do oil/coolant/spark plug ect changes at the weekend. I'll suppose I'll know when the oil gets drained.

Tawny wrote:
For the fuel hoses, you need petrol-suitable hose, about a metre of it, with a diameter of 8 or 9 mm (EDIT: 6.5mm internal like the other poster said, sounds right). Both of these will be a snug fit over the fuel tap.


Yeah it's 6.5mm, just went and checked it.

Tawny wrote:
That's good. Check the airbox then, and replace all your hoses. With any luck it's just a cracked hose.


I hope so, but when measuring the ID of the fuel pipe I had a look, no cracks that I could make out Sad I'll try shortening the pipes once the oil change is done (pipes won't be here before Monday I expect).
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davebike
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PostPosted: 07:41 - 12 Jan 2017    Post subject: Reply with quote

I bet the oil level is high
The vacume tap is sticking open and on ER5's if that happens the carbs flood !

pull the pipe from the tap to the carbs off without the engine running and see if fuel continues to drip if so a repair kit may! fix it or fit a second in line tap and use it when parked up !
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Falco
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FredTheHorse



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PostPosted: 10:12 - 12 Jan 2017    Post subject: Reply with quote

Looked in the airbox this morning and found that the filter smells strongly of petrol so whatever else it may be as well, it's also the carbs.
There was also a small amount of oil in the bottom of the airbox and a decent amount came out of the bunged up breather tube. Indicative of anything?

davebike wrote:
I bet the oil level is high
The vacume tap is sticking open and on ER5's if that happens the carbs flood !

pull the pipe from the tap to the carbs off without the engine running and see if fuel continues to drip if so a repair kit may! fix it or fit a second in line tap and use it when parked up !


I don't think the tap is failing. There was no leaking from the tube when I took it off and it's been disconnected all night with no sign of leakage.
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Falco
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FredTheHorse



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PostPosted: 15:11 - 13 Jan 2017    Post subject: Reply with quote

Opened and cleaned the float bowls today, a little gunk on the bottom but otherwise clean. One float needle looks a bit worn (I think?), also had some gunk in the valve seat:

http://s27.postimg.org/utk1lxppv/DSC00448.jpg

Does this even count as wear?:

http://s27.postimg.org/iud4sd9ir/DSC00449.jpg

They have both been replaced anyway because the replacements arrived early.

Drained the oil, definitely a petrol smell to it, but (by some miracle) no obvious metal flakes/chunks/dust. Perhaps the engine will survive this after all.
Some emulsion but I am going to have a good stir about when I put the carbs back on, to check for debris.

http://s27.postimg.org/4vgffwk8j/DSC00445.jpg

Next up is to replace oil and filter (with cheap Wilkos stuff, to be replaced with the actual proper oil when/if the leaks stop, and then run it for 5 minutes to check for leaks.
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mudcow007
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PostPosted: 16:17 - 13 Jan 2017    Post subject: Reply with quote

those valves do look a bit worn, but for 6 or what ever they are its worth doing

I use Wilko oil in my Bandit, have done for years - its fine

You will always get a bit of emulsion from cold starts etc, a longish ride will clear it all anyways
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Falco
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FredTheHorse



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PostPosted: 19:28 - 13 Jan 2017    Post subject: Reply with quote

[EDIT]: Got it started! For some reason it wouldn't start with the choke on full, only on half?

Still got a distressingly pronounced tapping sound exactly like this actually, am I being paranoid, is that a noise it should make (bearing in mind that the ticking stays when the revs go up)

mudcow007 wrote:
those valves do look a bit worn, but for 6 or what ever they are its worth doing

I use Wilko oil in my Bandit, have done for years - its fine

You will always get a bit of emulsion from cold starts etc, a longish ride will clear it all anyways


Yeah, for the cost I figured it was as well to replace them.

The oil is just sacrificial; oil, once the bike starts I'll let it get around the engine and drain it off to remove any vestiges of petrol that didn't come out the 1st time.
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Tawny
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PostPosted: 21:00 - 13 Jan 2017    Post subject: Reply with quote

Falco wrote:
Still got a distressingly pronounced tapping sound [url=https://www.youtube.com/watch?v=-1rEwDd-5fU]exactly like this actually


That one sounds exactly how it's supposed to sound, except very slightly lopey (maybe it's just been started from cold, or the carbs need balancing). The high-pitched, resonant, bell-metallic sound is normal.
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Falco
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PostPosted: 11:07 - 15 Jan 2017    Post subject: Reply with quote

Tawny wrote:
Falco wrote:
Still got a distressingly pronounced tapping sound [url=https://www.youtube.com/watch?v=-1rEwDd-5fU]exactly like this actually


That one sounds exactly how it's supposed to sound, except very slightly lopey (maybe it's just been started from cold, or the carbs need balancing). The high-pitched, resonant, bell-metallic sound is normal.


Cheers, I guess even bigger bikes with tappets sound clacky. Took me a while to get used to it on the CG, I expect I'll get used to it on this as well.

Got a fuel tap rebuild kit arriving next week and I'll put the new pipes onto the tank. Might try putting a couple of those spring loaded couplers into the lines, so taking off the tank isn't such a ball ache in the future.

http://www.bits4motorbikes.co.uk/images/PartAccessoriesImages/Motorbike-Accessories/Quick-release-fuel-line-coupler-6mm.jpg
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