Manual fuel tap issues.

[Lucky Phil]

Some of you may be aware of my ongoing frustration with these things. Briefly I've had one that refused to close off and another that has leaked when in the open position. Time to investigate. I suspected that the issue was junk seals and it turned out I was correct. I carefully removed the crimped section of the aluminium operating knob so I could screw it off the body and remove the internal plunger. The seals were toast which was causing the leaking in the open position. Bearing in mind that this thing gets used once in a blue moon the seals shouldn't have an issue really. So seals removed measured up and left in fuel overnight. I also tested a seal from an elcheapo kit I bought at the local Aldi store for comparison. No idea what the Aldi seal is made of but it was almost an identical size to the original. The first image shows the two seals after 24 hours in fuel ( the originals hadn't seen fuel for a week or so) As you can see the original has swelled a lot, around 1 mm in dia.

So if your manual tap is difficult to open and shut and needs pliers to do so here's your reason. Garbage non fuel compatible seals. My cheap control seal is fine and hasn't swelled at all. This sort of thing drives me nuts, to save pennies they use rubbish seals and to compound the issue they aren't replaceable.......until now,hopefully.

The difference in the seal sizes is quite obvious after 24 hrs in fuel.

    

So what we need is Viton or FKM seals which I suspect will need to be 10 mm ID X 2.4 mm CS. I'll confirm this soon.

The problem is what to do now with the the tap and its lack of open stop since we have removed the crimped section from the knurled nut. The issue for me is the lack of equipment. I've got plenty of nice ideas but dont have a mill which would allow me to do it properly. What I came up with is in the following image. I drilled and tapped the plunger for a 4 mm grub screw that can be inserted into its hole through the tap outlet. This grub screw when installed now forms the down stop for the plunger internally by it striking the inner bottom edge of the outlet hole replacing the crimped section of the aluminium knurled nut. The only issue I had was that I drilled and tapped the plunger hole about 1 mm too high which caused issues when the tap was closed. I resolved this by opening up the throat of the outlet port up near the closed seal face. Downside? a reduction in outlet area but i doubt it would be an issue as the inlet and filter screen are smaller than the tap outlet spigot ID.Next time I'd drill and tap a 6mm access hole on the tap body opposite the outlet port and make the 4mm hole in the plunger all the way through. I'd then have a 4mm stainless grub screw with the stop end turned down to 2 mm and it would be accessed through the 6 mm body screw from the opposite side. This would be much neater and minimise the loss of outlet area. The 6 mm access screw hole would need to be sealed with some thread sealer but the tap could be easily pulled apart for seal replacement and servicing.Note here only 1 seal is fitted to the plunger.   

I give this idea to the greater Guzzi community and forego retiring in luxury on the Caribbean on the obvious fiscal benefits I could derive from patenting etc.

Ciao 

   

[MartyNZ]

Good idea for a repair. My tap needs polygrips to open or close it, so your scheme might be on the horizon.

Do you want some DuPont Krytox grease to use when you assemble the tap? I can send a squeeze over to you.

[Lucky Phil]

17 minutes ago, MartyNZ said:

Good idea for a repair. My tap needs polygrips to open or close it, so your scheme might be on the horizon.

Do you want some DuPont Krytox grease to use when you assemble the tap? I can send a squeeze over to you.

Haven't thought about the final assembly yet but that's an idea. My Aldi seals are a little small on the CS at 2.1 mm so I'm going to order some 2.4 and 2.5 Viton seals this week and test them out. 

Ciao

[knumbnutz]

Hey Phil, 

Just a question since you have it apart, would drilling and threading at the small end in a lathe and putting a stop in along the axis work?

Could be adjusted for height this way.

 

[Lucky Phil]

18 minutes ago, knumbnutz said:

Hey Phil, 

Just a question since you have it apart, would drilling and threading at the small end in a lathe and putting a stop in along the axis work?

Could be adjusted for height this way.

 

The issue there is that the plastic strainer threads into the body ID. Do you mean a stop that somehow uses the top surface of the body on the tank side? If so you would need to leave the strainer off and you would also lose inlet flow.

I thought of a better solution initially but you need a Mill. Drill a 6 mm hole in the body opposite the outlet and use a screw with a 3mm spigot/projection machined at the end maybe 4 or 5 mm long that engages a 3 mm wide x 2 mm deep x 6 mm long slot machined into the plunger minor diameter. Insert the screw with the spigoted end which engages the slot in the plunger and you have your down stop and a guide to prevent the plunger rotating and you lose no flow at all. Its then dismantleable and all thats needed is a drop of sealer on the stop screw.

My only real issue is machining the slot in the plunger.

Ciao   

Edit, sorry just saw your modification in the image. Good idea but as above serious flow issues and loss of the strainer.

[Lucky Phil]

Ok so I ordered some Orings. My first preference was 10.3 x 2.4 Viton but they were special order at $3 something dollars each min 25 which would be ok except this is proof of concept so I went with 10X2.5 vitons. I'll need to widen the o ring grooves as well because they are too narrow even for the std orings. I fitted or tried to fit one of the std rings on the plunger after being in fuel and it was hopeless way too big everywhere, no wonder they generally hold fuel but you cant operate them.

I also thought bugger it and had an attempt at modifying the unit to my preferred design. I slotted the plunger by hand with a tiny cutter and a porting tool. Turned out better than I expected and works perfectly. So now the stop is internal and the unit can be serviced. I'll use a 4 mm stainless grub screw with a hex socket instead of the steel button head in the image which I had laying around. Some blue loctite on that will seal it and prevent loosening.

Seriously someone like Chuck with his skills and machinery could do this mod a lot better and with greater accuracy in under an hour.

 

Ciao    

[Lucky Phil]

So I got my FKM seals in the not preferred 10x2.5 dimension and they dont work. Just too big. Sizing up orings on a piston into a bore is quite a complicated thing even after I used a sizing programme. My preferred size per the programme is 10.3 x 2.4 but they wanted me to order 25 but when I called today they said that they can get as many as I like overnight no min order....Geeze.

So I'm going the Lucky Phil non tech route and getting about 4 different sizes and seeing what works. At 30 cents each for the NBR and $2 each as it turns out for the FKM's I'll just use the scatter gun approach and hopefully be able to learn something and pass it on. My machinist mate recons that with a cheap little XY vice attachment on the pedestal drill and a 2 fluted mill drill you can cut the slot accurately in the plunger.  

The object here is to develop a process that people can do at home with basic tools to rebuild and upgrade this tap assy.

Ciao      

[LowRyter]

Mine was leaking and replaced by an emergency repair with plumbing "L" fitting and  a cork in the tankbag. 

I purchased an outboard boat fuel tank quickconnect.  I mean to install it sometime hopefully without a huge mess.  It's about 3 in long so I could have issues fitting it under the tank and might have a vapor lock issue with inadequate heat protection. 

By comparison, the little cork doesn't seem too bad.

[Lucky Phil]

6 hours ago, LowRyter said:

Mine was leaking and replaced by an emergency repair with plumbing "L" fitting and  a cork in the tankbag. 

I purchased an outboard boat fuel tank quickconnect.  I mean to install it sometime hopefully without a huge mess.  It's about 3 in long so I could have issues fitting it under the tank and might have a vapor lock issue with inadequate heat protection. 

By comparison, the little cork doesn't seem too bad.

I would welcome any other solution than the tap in reality. A std readily available QD is 5/16 (8mm) and the V11 outlet is 1/2" (12mm). The other issue is space under there specifically length. There isn't much if any spare distance between the tap outlet and the pump inlet for a 1/2 inch tube with its lack of flexibility to bend in an S shape. Most QD's take up 50mm of more which doesnt leave any room for the hose to bend. half inch rubber hose is way less flexible than 5/16. I spent a lot of time trying to source extra flexible 1/2' hose without luck.

Ciao  

[LowRyter]

Phil, there's always the cork.

[Lucky Phil]

On 4/9/2020 at 8:31 AM, LowRyter said:

Phil, there's always the cork.

Well after messing about with different seal size variations and not having a lot of luck in the body sealing I decided to crack check the body with the dye check kit and yep it's cracked. Once I had the location I could see it with the 10x glass. Explains why it wouldnt hold suction in the open position ( I used the time honoured block all the open ports and suck on the one left and seal it with the tongue) but would in the "almost closed" position which is pretty useless to me. The location of the crack was near the closed end. This is a good designed tap let down by I suspect cheap Chinese reproduction. Cant imagine the OEM using non fuel proof seals and the housing cracking.

Ciao  

[MartyNZ]

2 hours ago, Lucky Phil said:

... I decided to crack check the body with the dye check kit and yep it's cracked...

A new one for €33.

 https://www.ebay.it/itm/MOTO-GUZZI-1100-Sport-cali-3-IE-Daytona-Contingente-V11-Benzina-Carburante/352055765103?hash=item51f828a86f:g:uscAAOSw241YbR67&redirect=mobile

[Lucky Phil]

15 hours ago, MartyNZ said:

A new one for €33.

 https://www.ebay.it/itm/MOTO-GUZZI-1100-Sport-cali-3-IE-Daytona-Contingente-V11-Benzina-Carburante/352055765103?hash=item51f828a86f:g:uscAAOSw241YbR67&redirect=mobile

Thanks Marty cheaper than MG cycles when you consider the postage costs. I'd love to use something of better quality but the 1/2" outlet is the issue. Having said that I pulled the original electric tap out and removed the solenoid and lo and behold although the barb is 1/2" or 12 mm if you like the actual feed hole is only 5mm. So the only reason for the 12mm barb is to keep the hose a consistent size for the 12mm pump inlet not for flow purposes. There a a number of 8mm or 5/16 outlet taps out there with 16x1mm threads but it would mean machining up a 12mm to 8mm step down adaptor. You could then use std 5/16 or 8mm hose for 90% of the fuel line to the pump which is way more flexible and takes up less room. Things to consider.

Ciao  

[Kiwi_Roy]

Perhaps just mount a quick connect in the bottom of the tank, there's really no need to shut the fuel off on a FI bike.

Do you have an in tank or outside fuel pump?

Personally I never had a problem with the Electric Petcock.

[Lucky Phil]

46 minutes ago, Kiwi_Roy said:

Perhaps just mount a quick connect in the bottom of the tank, there's really no need to shut the fuel off on a FI bike.

Do you have an in tank or outside fuel pump?

Personally I never had a problem with the Electric Petcock.

Yes Roy I've never had an issue with the electric one either. Problem with the QD solution is the outlet is 1/2" or 12mm which is not a readily available QD although the electronic unit uses a 12mm hose as well but the actual outlet hole is only 5mm. So you could use a 5/16 outlet tap and convert to a 5/16 hose with a 5/16 to 1/2" reducer at the pump inlet but even the 5/16 QD connector takes up about 50 mm of length in the hose and if you look at the installation you dont have the distance/length for a QD and get a nice S shape from the outlet to the pump inlet. The distance is too short esp if you use a reducer as well and lose more bend distance.

The manual tap is a nice design let down by poor execution and componentry. What we get from suppliers now is a cheap copy of the original and people put up with needing to use a pair of pliers to open and close it. 

Ciao