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mrodey



Member Since: 18 May 2023
Location: Svedala
Posts: 32

Sweden 2009 Defender 110 Puma 2.4 CSW Scotia Grey
2.4 Puma losing fuel prime?
So I've been working on this for months and still can't figure out the problem. My 2008 Defender 2.4 suddenly stopped starting. She turns over fine, battery is new, new filter, starter recently replaced, etc.

The ONLY way I can get it to start it to use an air compressor to blow air into the fuel tank (wife) while I press the air release valve on the fuel line in the engine compartment until fuel comes out then quickly start up the car and after 30 seconds she will fire up. If I shut it off then after 10 seconds she wont start again till I pressurize the tank.

I've inspected all fuel lines but see no fuel leaks or cracks. Any suggestions from people who have this problem of what could cause fuel to drain back into the tank? Can a bad fuel tank vent breather hose allow air in as I'm guessing that is a one way air valve?

I'm out of ideas.
Post #1058966 30th Jan 2025 11:16am
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landy andy



Member Since: 15 Feb 2009
Location: Ware, Herts
Posts: 5789

2006 Defender 110 Td5 USW Zermatt Silver
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.
Post #1058970 30th Jan 2025 11:32am
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blackwolf



Member Since: 03 Nov 2009
Location: South West England
Posts: 17540

United Kingdom 2007 Defender 110 Puma 2.4 DCPU Stornoway Grey
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.
Post #1058971 30th Jan 2025 11:32am
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cretesimon



Member Since: 01 Nov 2021
Location: heraklon
Posts: 55

Greece 
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
Post #1059037 30th Jan 2025 8:42pm
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andy63



Member Since: 30 Jun 2023
Location: north east
Posts: 592

United Kingdom 
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..
Post #1059069 31st Jan 2025 8:59am
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John P



Member Since: 26 Dec 2013
Location: West Sussex
Posts: 326

United Kingdom 2012 Defender 90 Puma 2.2 SW Corris Grey
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.
Post #1059092 31st Jan 2025 11:02am
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landy andy



Member Since: 15 Feb 2009
Location: Ware, Herts
Posts: 5789

2006 Defender 110 Td5 USW Zermatt Silver
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.
Post #1059093 31st Jan 2025 11:26am
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mrodey



Member Since: 18 May 2023
Location: Svedala
Posts: 32

Sweden 2009 Defender 110 Puma 2.4 CSW Scotia Grey
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.
Post #1059105 31st Jan 2025 1:47pm
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blackwolf



Member Since: 03 Nov 2009
Location: South West England
Posts: 17540

United Kingdom 2007 Defender 110 Puma 2.4 DCPU Stornoway Grey
Thumbs Up Very Happy
Post #1059108 31st Jan 2025 2:15pm
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jim4244



Member Since: 13 Apr 2014
Location: Bedfordshire
Posts: 831

England 2007 Defender 90 Puma 2.4 CSW Zermatt Silver
This sort of thing is what I love about this forum. The knowledge base and peoples willingness to help is just outstanding! Thumbs Up

Jim
Post #1059109 31st Jan 2025 2:32pm
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Caterham



Member Since: 06 Nov 2008
Location: Birmingham
Posts: 6316

England 2011 Defender 110 Puma 2.4 XS CSW Stornoway Grey
/\ exactly Thumbs Up

and a great deal of that knowledge will go if ever Blackwolf decides to pack his bags and walk Bow down
Post #1059112 31st Jan 2025 3:26pm
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