 | Home > Puma (Tdci) > Low pressure fuel line pressure |
 
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| andy63 Member Since: 30 Jun 2023 Location: north east Posts: 579  
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I was reading a thread a while back where the differences between 2.4 and 2.2 lp fuel systems were been discussed and this would likely be best added to that thread but can't find which one it was now๐ซ
I've been meaning to check out my 2.2 for a while and was trying to get a connector to fit that bleed point under the green cap on the lp fuel line to the hp pump.. those efforts failed..even asking a couple of dealers they couldn't say they had ever used the point for test purposes.. I'm not at home but managed to lash up a little adapter that did for now and allowed the connection of a pressure transducer.. So, I knew the in tank electric pump cut out after about 10 seconds after the ignition was switched on and I had thought it just ran to prime a mechanical lift pump.. That assumption appears wrong and in fact when the engine started the electric pump does run , supplying about 7.5 psi on the lp line to the hp pump..  Click image to enlarge Click image to enlarge Another trace taken over a longer time base showing the pump current in red, with the pressure trace in blue above Click image to enlarge |
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10th Jan 2025 8:58pm |
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| andy63 Member Since: 30 Jun 2023 Location: north east Posts: 579
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I posted this a few days ago ..and shortly after noticed the picture of combined current and pressure was showing a current between a positive and negative value...because of the time base is had used it just appears a huge thick mass of red..with an upper and lower value
Anyway..before taking the trace I had done a quick voltage drop test over the pump inline fuse and the mv value did suggest a current around 5 or 6 amps, so I've been trying to find out why my current trace is the way it is.. Fortunately a lad who knows scopes suggested I must have been pressing the zero button on the current clamp while the scope was running, thus the bad trace..I've yet to try and confirm this by replicating the fault but I do remember doing just that.. Been back to check the current, and be a bit more careful. ๐๐ Also brought the time base right down to get some more detail.. In the attached photo you can see a repeating pattern, which suggests an 8 segment commutator , which isn't to bad in terms of condition, and shows a pump speed of around 5000rpm.... The current is in the range the fuse voltage drop reading suggested.. Click image to enlarge |
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12th Jan 2025 8:04pm |
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| andy63 Member Since: 30 Jun 2023 Location: north east Posts: 579
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An essential bit of kit for correct diagnosis of any modern vehicles..
IMHO... I post on another lr forum as well and very few are interested๐ซ๐คฃ, but i find it interesting and post just in case it helps others or indeed anyone can add anything to help me.. Like my odd current values in the photo i posted above..but hopefully got that sorted now ๐๐ |
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13th Jan 2025 11:05am |
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| MK Member Since: 28 Aug 2008 Location: Santiago Posts: 2436  
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I think the only way to go is with the picoscope. A bit pricey though and the entry level pico struggles with some measurements. Puma 110" SW
............................................................. Earth first. Other planets later |
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13th Jan 2025 11:13am |
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| andy63 Member Since: 30 Jun 2023 Location: north east Posts: 579
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I know what you mean..pico have established themselves and I believe are the go to people for a lot of the automotive industry...
But many garages and mechanics use scopes from other manufacturers.. Hantek. Rotkee. owon ..and most of the scan tools at the high end have scopes built in which really does make their set up and use more convenient.. I'm not sure i go with your thoughts that you need the high end pico.. even basic scopes and not even specific automotive are capable for just about all automotive work..it just means you have to be prepared to get the thing out and use it as much as possible..preferably on known good to start with..in fact a lot of scope diagnosis is based on comparisons with known good results, and experience of course..๐ |
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13th Jan 2025 1:58pm |
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