Unable to Stop the Fuel

[Craig Shelley]

Hi,

We had a bit of a surprise while changing the on-engine fuel filter today. I thought I'd share it to hopefully prevent someone else from having the same mishap.

 

Despite turning off the tank fuel valve, fuel kept flowing from the engine fuel filter.

It turned out that the fuel tank had been over filled above the height of the fuel return line, which doesn't have a shut off valve. We believe the fuel was back-feeding through the injector pump.

I can't find anything in the BSS which mitigates against this scenario as in my opinion being unable to stop a fuel supply is a hazard.

The fuel had recently been filled, but the level appears to be sensible. Looking at the side of the tank, it's obvious that the level is above the fuel return line entry point.

 

Is there supposed to be a shut off valve or check valve in the fuel return line to prevent this?

 

Regards,

Craig

[Chewbacka]

I have a shut off valve in both fuel feed & return lines for this very reason.  I would fit one  when the fuel level has dropped to a safe level.

 

added - my views on the bss, as per your comment above, shows this is yet another example of the poor way in which the bss is written.  The bss does require all fuel feed lines to comply with emergency shut-off requirements as per 2.13.1.  It seems reasonable to argue that a return is not a feed especially as it fails to define a fuel feed line, therefore is not included in this requirement.  But in your case a return line under certain circumstances becomes a feed, at which point in my opinion it must be included because it is now a feed.  It seems the bss did anticipate this by stating later in that section that ALL fuel lines below the top of the tank must comply with this section.

 

Basically the section heading is wrong.

 

Probably the result of committee edits and a failure to adequately proof read before issue.

Edited September 26, 2019 by Chewbacka

[ditchcrawler]

4 hours ago, Chewbacka said:

I have a shut off valve in both fuel feed & return lines for this very reason.  I would fit one  when the fuel level has dropped to a safe level.

 

 

Same here 

4 hours ago, Chewbacka said:

 

 

added - my views on the bss, as per your comment above, shows this is yet another example of the poor way in which the bss is written.  The bss does require all fuel feed lines to comply with emergency shut-off requirements as per 2.13.1.  It seems reasonable to argue that a return is not a feed especially as it fails to define a fuel feed line, therefore is not included in this requirement.  But in your case a return line under certain circumstances becomes a feed, at which point in my opinion it must be included because it is now a feed.  It seems the bss did anticipate this by stating later in that section that ALL fuel lines below the top of the tank must comply with this section.

 

Basically the section heading is wrong.

 

Probably the result of committee edits and a failure to adequately proof read before issue.

Maybe tying with another point where they say takeoffs should be as high a practical, in a lot of cases this is via the top of the tank with an upstanding loop, mine are about 2 inches down due to extended tank for more capacity.

[Mike Adams]

I don't agree with a fuel shut off in the return/leak off line. If is shut off in error pressure could build up causing a pipe/fitting to fail with the potential to cause a fire. Much better to have the reurn on the top of the tank or connected into the fuel filler line above the tank.

[ditchcrawler]

Just now, Mike Adams said:

I don't agree with a fuel shut off in the return/leak off line. If is shut off in error pressure could build up causing a pipe/fitting to fail with the potential to cause a fire. Much better to have the reurn on the top of the tank or connected into the fuel filler line above the tank.

From looking at my boat I dont see how pressure could build up as the same line is connected to the top of the filters

[Ex Brummie]

If you have no shut off in the return, disconnect the flexi from the filter and lift above the fuel tank level. Can you guess how I know?

[Craig Shelley]

Would fitting a non-return check valve instead of another manual shut-off valve, be an acceptable solution?

[Chewbacka]

18 minutes ago, Craig Shelley said:

Would fitting a non-return check valve instead of another manual shut-off valve, be an acceptable solution?

The bss is not clear, it lists methods which are acceptable, but is not clear if there are others not listed that would be acceptable.  However my feeling is that the intention was to require one of the options given.  A check valve is not one of the options.  So my opinion is no.

 

As an aside an anti-siphon valve can be used, but must have been installed by the boat builder.  But under the regs, if you do a diy fit out you are considered to be the builder, so I could fit one to my boat.  In your case from your description it is not a siphon effect, more an overflow as the connection to the tank is simply too low, so an anti siphon device would not be appropriate.

Edited September 26, 2019 by Chewbacka

[blackrose]

I don't really understood this? I don't have a shut off valve on my return line. I must have changed my water separator/sediment trap and fuel filter 10 times on this boat and it's never been a problem. What am I doing differently to the OP and why do I need a shut off valve on the return?

Edited September 26, 2019 by blackrose

[WotEver]

8 minutes ago, blackrose said:

I don't really understood this? I don't have a shut off valve on my return line. I must have changed my water separator/sediment trap and fuel filter 10 times on this boat and it's never been a problem. What am I doing differently to the OP and why do I need a shut off valve on the return?

Your return is above the level of the diesel in the tank

[Chewbacka]

9 minutes ago, blackrose said:

I don't really understood this? I don't have a shut off valve on my return line. I must have changed my water separator/sediment trap and fuel filter 10 times on this boat and it's never been a problem. What am I doing differently to the OP and why do I need a shut off valve on the return?

Probably because your return pipe connection to the tank does not have a dip tube and is above the fuel level.  

 

Added - if by design it can not be a feed it does not need a valve, but if it could ‘feed’ but you just don’t fill your tank high enough, then you should have a valve.

Edited September 26, 2019 by Chewbacka

[blackrose]

3 minutes ago, WotEver said:

Your return is above the level of the diesel in the tank

Can't be. The top of the tank is the underside of the deck and my tank is generally kept full.

4 minutes ago, Chewbacka said:

Probably because your return pipe connection to the tank does not have a dip tube and is above the fuel level.  

No I don't think so.

[Craig Shelley]

5 hours ago, blackrose said:

Can't be. The top of the tank is the underside of the deck and my tank is generally kept full.

No I don't think so.

Perhaps your fuel injection pump has a different design. In our case the fuel must have been back flowing through the pump.

Another thing worth noting is that the fuel which has back-flowed through the system has effectively bypassed all 3 fuel filters.

The filter we were attempting to change was the on-engine filter, which is the last in the chain.

[ditchcrawler]

10 hours ago, Chewbacka said:

 

 

As an aside an anti-siphon valve can be used, but must have been installed by the boat builder.  But under the regs, if you do a diy fit out you are considered to be the builder, so I could fit one to my boat.  In your case from your description it is not a siphon effect, more an overflow as the connection to the tank is simply too low, so an anti siphon device would not be appropriate.

Which regulation is this?

 

[Alan de Enfield]

26 minutes ago, ditchcrawler said:

Which regulation is this?

 

The BSS (mentioned  several posts ago)

 

An effective emergency shut‐off must be installed in all fuel feed lines. Any of
the following methods are acceptable:
• a manual shut‐off valve or cock; or,
• all fuel lines, including those on the engine, being above the level of the top of the
tank; or,
• an anti‐siphon valve at the tank, providing it was installed by the boat builder; or,
• an electrically operated valve at the tank activated to open only during
engine starting or running, provided that a manual emergency operating or
bypassing device is present.
NOTE – if an examiner cannot verify a claim from an owner that the emergency shut‐off facility is provided
by way of an anti‐siphon valve or an electrically operated valve, they should contact the BSS Office for help
verifying the claim.
Advice to owners – when purchasing solenoid controlled shut‐off valves an assurance should be sought from
the supplier as to their suitability for use with the fuel in use.

[Chewbacka]

1 hour ago, ditchcrawler said:

Which regulation is this?

 

Recreational craft directive defines who is responsible for ce marking as builder or importer.

[Ex Brummie]

Having encountered the problem, wait until your fuel is lower than a convenient place for a valve, and fit one. If your feed and return pipes run side by side, then adjacent to the existing pipe is best.

[ditchcrawler]

4 hours ago, Alan de Enfield said:

The BSS (mentioned  several posts ago)

 

An effective emergency shut‐off must be installed in all fuel feed lines. Any of
the following methods are acceptable:
• a manual shut‐off valve or cock; or,
• all fuel lines, including those on the engine, being above the level of the top of the
tank; or,
• an anti‐siphon valve at the tank, providing it was installed by the boat builder; or,
• an electrically operated valve at the tank activated to open only during
engine starting or running, provided that a manual emergency operating or
bypassing device is present.
NOTE – if an examiner cannot verify a claim from an owner that the emergency shut‐off facility is provided
by way of an anti‐siphon valve or an electrically operated valve, they should contact the BSS Office for help
verifying the claim.
Advice to owners – when purchasing solenoid controlled shut‐off valves an assurance should be sought from
the supplier as to their suitability for use with the fuel in use.

Thanks for that Alan.