No fuel delivery....Air in fuel pipe

[johnny650]

Sounds like the vent in the petrol cap is blocked, take the cap off and listen for a rush of air entering the tank and also observe if the column of air in the pipe reduces/disappears.

please see the last line in my initial post

The position of the banjo wont make any difference what so ever as it is lower than the tank exit in whatever position its in.

Correct .........but the banjo will only fit on one way .........facing out so its academic

You could check the circular gauze that sits behind the banjo just to make sure thats clear.

I have 6x jetex carbs which are cycled with different jets slides etc and there are still air locks so its unlikely to be the gauze filter in all of them............. besides the question we should be asking is ' How and Where is the air entering a closed system.

I’ve had problems with jetex carb banjo’s touching the engine mount, simple solution i found was to stuff some rubber between the tank and the strap raising it up slightly.

that is a very good idea .............however this is not a vertical height problem.............. its a horizontal one . The petrol tap knuckle joint is jammed against the side of the carb slide pivot . Either the carb needs pulling outwards or the manifold needs to be longer or the tank needs moving sideways to make sufficient clearance.

[Scooterdude]

Sounds like the vent in the petrol cap is blocked, take the cap off and listen for a rush of air entering the tank and also observe if the column of air in the pipe reduces/disappears.

please see the last line in my initial post

The position of the banjo wont make any difference what so ever as it is lower than the tank exit in whatever position its in.

Correct .........but the banjo will only fit on one way .........facing out so its academic

You could check the circular gauze that sits behind the banjo just to make sure thats clear.

I have 6x jetex carbs which are cycled with different jets slides etc and there are still air locks so its unlikely to be the gauze filter in all of them............. besides the question we should be asking is ' How and Where is the air entering a closed system.

I’ve had problems with jetex carb banjo’s touching the engine mount, simple solution i found was to stuff some rubber between the tank and the strap raising it up slightly.

that is a very good idea .............however this is not a vertical height problem.............. its a horizontal one . The petrol tap knuckle joint is jammed against the side of the carb slide pivot . Either the carb needs pulling outwards or the manifold needs to be longer or the tank needs moving sideways to make sufficient clearance.

Oh dear, looks like I rattled someones cage there then

Regarding the position of the jetex banjo its an easy enough thing to file/dremmel the three flat sides of the positioning square to get it to were you want it, so no the position isn’t academic.

And despite me posting a couple of days ago nobody has mentioned my mistake when i said put some rubber under the tank to raise it away from the banjo, haha, it was a long hard day and i was thinking of the petrol tap contacting the engine mount and not the banjo lol.

[wrecklessrobbie]

Can you put a photo up of the fuel tap knuckle, carb etc.

My origianl fuel tap on my s2 was broken. So i bought a replacement. Also a rear exit fast flow tap.
The new fuel tap rod was from a gp/s3. It was much longer. So i was able to alter the fuel tap into the frame more taking up the slack of the fuel tap. It then avoids fouling on the carb.
Maybe a longer fuel tap will give you more adjustment.

[johnny650]

Oh dear, looks like I rattled someones cage there then

Regarding the position of the jetex banjo its an easy enough thing to file/dremmel the three flat sides of the positioning square to get it to were you want it, so no the position isn’t academic.

And despite me posting a couple of days ago nobody has mentioned my mistake when i said put some rubber under the tank to raise it away from the banjo, haha, it was a long hard day and i was thinking of the petrol tap contacting the engine mount and not the banjo lol.
[/quote]


I may be a little irritated its true but i do get exasperated when people don't bother to read the initial post and the rest of the thread. Plus my back is constantly going into spasm which is excruciatingly painful so I probably haven't got much patience at the moment I'm afraid.


The Jetex Banjo will fit on the carb facing any direction you want it to

BUT that is no use when it is impossible to fit the fuel hose onto the banjo when its facing down or up due to the proximity of the mag housing and the engine mount. I have explained all this previously in this thread if you go and look .

I believe that a slight leak on the fuel hose connections to the petrol tap , banjo or inline fuel filter is allowing some fuel to leak ot of the fuel line over night which is getting replaced with air . That air is causing an airlock for the fuel.

I believe that the air is getting drawn in through the petrol tap due to the seals and gaskets being distorted and damaged because the petrol tap shaft is being at such a sharp angle.

i shan't be able to check this until my back stops going into spasm probably about 2x weeks time so its all speculation at the moment but thanks for your input and suggestions .

[johnny650]

Oh dear, looks like I rattled someones cage there then

Regarding the position of the jetex banjo its an easy enough thing to file/dremmel the three flat sides of the positioning square to get it to were you want it, so no the position isn’t academic.

And despite me posting a couple of days ago nobody has mentioned my mistake when i said put some rubber under the tank to raise it away from the banjo, haha, it was a long hard day and i was thinking of the petrol tap contacting the engine mount and not the banjo lol.

I may be a little irritated its true , my back is constantly going into spasm which is excruciatingly painful so I probably haven't got much patience at the moment I'm afraid.


The Jetex Banjo will fit on the carb facing any direction you want it to

BUT that is no use when it is impossible to fit the fuel hose onto the banjo when its facing down or up due to the proximity of the mag housing and the engine mount. I have explained all this previously in this thread if you go and look .

I believe that a slight leak on the fuel hose connections to the petrol tap , banjo or inline fuel filter is allowing some fuel to leak ot of the fuel line over night which is getting replaced with air . That air is causing an airlock for the fuel.

I believe that the air is getting drawn in through the petrol tap due to the seals and gaskets being distorted and damaged because the petrol tap shaft is being at such a sharp angle.

i shan't be able to check this until my back stops going into spasm probably about 2x weeks time so its all speculation at the moment but thanks for your input and suggestions .
[/quote]

[johnny650]

Can you put a photo up of the fuel tap knuckle, carb etc.

My origianl fuel tap on my s2 was broken. So i bought a replacement. Also a rear exit fast flow tap.
The new fuel tap rod was from a gp/s3. It was much longer. So i was able to alter the fuel tap into the frame more taking up the slack of the fuel tap. It then avoids fouling on the carb.
Maybe a longer fuel tap will give you more adjustment.

This sounds like a good idea . I have been looking for an image but I have backed up all hard drive a few days ago so its going to take a bit of searching for.

This wasn't such a problem on the previous engine using the same tap, carb and lever so it must be something to do with the length of the 22mm manifold which is a replacement for the original 18mm . The 22mm manifold must be shorter .
I think I will probably try and weld an extension on the manifold so that the carb has more clearance to the petrol tap and mount

[wrecklessrobbie]

Would it not be easier to take the manifold off.
Check it against another manifold to see if it is shorter. before trying to weld it.
Sorry i dont really have the answers you need.
But one thing i have found.
If my scooters p155 me off or im in a black dog period...i walk away from them.
Leave them til i am in a better frame of mind or feel capable if doing the jobs i need to do

[HxPaul]

The position of the banjo wont make any difference what so ever as it is lower than the tank exit in whatever position its in.

Correct .........but the banjo will only fit on one way .........facing out so its academic ;


So is the petrol pipe

[johnny650]

The position of the banjo wont make any difference what so ever as it is lower than the tank exit in whatever position its in.

Correct .........but the banjo will only fit on one way .........facing out so its academic ;


So is the petrol pipe

sorry its not clear what point you are making ?...........

Please read the rest of the thread where I have explained this in n'th detail, it should be clear by now surely

Allow me to repeat it one last time .

1. The banjo will fit on the carb in any one of 4x planes ie up, down, back and forward .

2. The fuel pipe will not fit onto the banjo in any position except with the banjo facing forwards.

This means that although one can physically fit the banjo in any position it would be pointless to do so because one could not get a fuel pipe to fit due to the proximity of the mag housing and the engine mounting .

[johnny650]

Would it not be easier to take the manifold off.
Check it against another manifold to see if it is shorter. before trying to weld it.

No its a lot easier to measure the manifold in situ first

Sorry i dont really have the answers you need.
But one thing i have found.

If my scooters p155 me off or im in a black dog period...i walk away from them.
Leave them til i am in a better frame of mind or feel capable if doing the jobs i need to do

very good idea except I do not have the choice at the moment

see my earlier post today

'Plus my back is constantly going into spasm which is excruciatingly painful so I probably haven't got much patience at the moment I'm afraid'