 | Home > Puma (Tdci) > 2.4 Puma losing fuel prime? |
 
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| landy andy Member Since: 15 Feb 2009 Location: Ware, Herts Posts: 5859  
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The fuel tank breather WILL allow air into the tank, but that is correct. To me your description indicates that the air leak is fuel supply pipework at the front / engine end of the system and it allow the fuel to run back to the tank.
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30th Jan 2025 12:32pm |
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| blackwolf Member Since: 03 Nov 2009 Location: South West England Posts: 17711  
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The obvious thing that springs to mind would be a leak in the bleed valve (the valve you are using when pressurising the tank) allowing fuel to drain back into the tank when the engine is not running.
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30th Jan 2025 12:32pm |
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| cretesimon Member Since: 01 Nov 2021 Location: heraklon Posts: 57 
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Once had one where the plastic fuel sender unit had cracked inside and letting air in to the diesel when trying to find the fault I started engine side by bypass the fuel system and running it on a fuel can straight to the pump
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30th Jan 2025 9:42pm |
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| andy63 Member Since: 30 Jun 2023 Location: north east Posts: 687
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Does the 2.4 have the same schrader type bleed valve as the 2.2.. on the lp fuel line to the hp pump??
If that's the valve you are using to bleed air it should have a green plastic cap and that has a rubber seal as well so should provide a bit extra security if the valve itself isn't seating.. Another likely candidate for air ingress would be the filter housing ..can't think of an easy way to check that other than removal, inspection and replacing to see if it helps.. |
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31st Jan 2025 9:59am |
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| John P Member Since: 26 Dec 2013 Location: West Sussex Posts: 342 
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I assume you have replaced the fuel filter? As there is no pump in the tank on the 2.4, I had to bleed my system to get it to run. This involved getting a bleeding kit, and sucking the fuel from the tank into the engine. After this my 2.4 started and ran no problem.
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31st Jan 2025 12:02pm |
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| landy andy Member Since: 15 Feb 2009 Location: Ware, Herts Posts: 5859
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If you suspect joints on the system you can smear some grease, or Vaseline over the joint which will temporarily stop the air going in. Possibly this might help with you diagnostics.
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31st Jan 2025 12:26pm |
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| mrodey Member Since: 18 May 2023 Location: Svedala Posts: 32  
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Blackwolf was correct! It was the schrader valve (yes Andy63 it's missing the green cap) that had gone bad. It was honestly the one thing I didn't try and now I feel so dumb. Some duct tape and zip tie to seal it off and the fuel stopped draining back into the tank. For now, some plumbers tape and an M12 capnut to replace the missing green plastic cap (been driving it for a long time with that missing and no problems). I'll order a new fuel line so I don't have a dodgy valve there.
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31st Jan 2025 2:47pm |
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| blackwolf Member Since: 03 Nov 2009 Location: South West England Posts: 17711
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31st Jan 2025 3:15pm |
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| jim4244 Member Since: 13 Apr 2014 Location: Bedfordshire Posts: 922  
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This sort of thing is what I love about this forum. The knowledge base and peoples willingness to help is just outstanding!
Jim |
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31st Jan 2025 3:32pm |
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| Caterham Member Since: 06 Nov 2008 Location: Birmingham Posts: 6324 
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/\ exactly
and a great deal of that knowledge will go if ever Blackwolf decides to pack his bags and walk  |
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31st Jan 2025 4:26pm |
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| andy63 Member Since: 30 Jun 2023 Location: north east Posts: 687
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Yes..any time I've been goggling an issue on my defender, it's odds on it will link to a thread thats been discussed on here at some point over the years
Invaluable info, and blackwolf and ianh have nearly always figured in the supply of information... Big thanks to you all.. 👍 |
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31st Jan 2025 5:58pm |
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| andy63 Member Since: 30 Jun 2023 Location: north east Posts: 687
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I was recently trying to find a connector for that bleed point to connect a pressure gauge to it.. I'm pretty sure that a standard m12 nut would not thread on fully.. I'm not at home and don't have access to me normal thread gauges etc so can't be sure of the thread pitch ..it might even be the m12 fine or another imperial with a close pitch.. with so few threads on the fitting the thread angle may not come in to play and make it more difficult to decide... if you are sure you have the right nut please let me know?? |
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1st Feb 2025 10:59am |
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| andy63 Member Since: 30 Jun 2023 Location: north east Posts: 687
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Well no response to that querry, and I'm home so have checked..
The thread fitting on the bleed point on the lp pressure line, that has a schrader type valve , is a bit of an odd ball... It has a 1.5 mm pitch.. so it's likely an m12 fine, although my little zeus data book has m12 fine down as a 1.25mm pitch.. May be of benefit to someone wanting to make up a connector..  Click image to enlarge |
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24th Feb 2025 1:16pm |
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| Ianh Member Since: 17 Sep 2018 Location: Essex Posts: 2248
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M12 standard is 1.75 and fine can be 1.25 or 1.5. Noting that some call 1.25 extra fine. So as long as you specify M12 1.5 you should be ok.
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24th Feb 2025 2:53pm |
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