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Are there two fuel pressure regulators? (4.2L)

Old Nov 4, 2024 | 08:52 AM
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Default Are there two fuel pressure regulators? (4.2L)

2003 S-Type, 4.2L, V8-base.

I know there's one

fuel pressure regulator sensor on the fuel rail, but is there a secondary that I'm not aware of?
 
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Old Nov 4, 2024 | 09:36 AM
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The fuel pressure is regulated by the PCM/ECM and the sensor on the fuel rail.

What is the issue with the vehicle?
 
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Old Nov 4, 2024 | 11:21 AM
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About four months ago out of the blue my car began having difficulty starting. It would take 4 separate cranking attempts to get it started (one odd quark was that if I let the car sit overnight it would start on first attempt, but everytime after that it would take 4 attempts). Had it at 5 different shops, no one could figure it out.

Along the way trying to get it figured out we've replaced a lot of sensors and parts at the recommendation of various shops as they sought to diagnosis and fix it: fuel pump, fuel filter, engine coolant temp sensor, fuel pressure sensor, spark plugs, MAF, PCV, injectors (3 different sets), etc.

After a few times at one particular shop (and $1000+ later...) they said they replaced the secondary fuel pump regulator VOILA, it's now starting on first attempt.I'm wondering where this secondar fuel pump regulator is and how I or the other shops missed this.

*Of course I've got some misfire issues going on cylinders 4 and 5 but at least the car fires up now.
 
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Old Nov 5, 2024 | 07:59 AM
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Originally Posted by mikesbaron
After a few times at one particular shop (and $1000+ later...) they said they replaced the secondary fuel pump regulator VOILA, it's now starting on first attempt...
Was there any sort of part number on the invoice? That might help identify what was actually replaced.
 
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Old Nov 5, 2024 | 08:33 AM
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No I haven't seen the invoice yet. They told me to take the car to drive it a few days before settling the bill. Of course in that time period the car through misfire codes 4/5 which I'm trying to resolve on my own before deciding if I need to take it back to them and settle the bill/invoice.
 
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Old Nov 12, 2024 | 03:54 PM
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Ok so here is what the latest shop said they replaced, which seemed to fix my intermittent starting problem. I want to find out where this item is located, because I previously had replaced my fuel pressure sensor (on the fuel rail) and it didn't fix my starting problem. Several times in and out of this shop and a few thousand $$$ later they replaced this part and now my car starts up regularly.

AJ8 7977 Fuel Pressure Regulator 1 @ $205.61

Where is it locatd on the car?

https://www.jaguarparts.com/oem-part...ulator-aj87977


 
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Old Nov 12, 2024 | 04:21 PM
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The fuel pressure sensor is located on the fuel rail. Here is an illustration from SNG Barratt's website:



 
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Old Nov 12, 2024 | 04:31 PM
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Ok yes that's one of the first ones I replaced when my car began having issues. Are there two of them on the car or one? Because the shop said it was a "secondary fuel regulator" that they replaced. To me that sounds as if there is another one. Or is the primary one part of the fuel pump or fuel line system?
 
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Old Nov 12, 2024 | 05:23 PM
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That is the only one I've ever seen.
 
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Old Nov 13, 2024 | 07:40 AM
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DOH! Then I'm the most staunch advocate for never using other than OEM or high quality name brand parts for all cars. This regulator is one that I initially had replaced at the beginnig of the debacle. Instead of paying for the oem part or at least a good quality brand I opted for a no brand one and here I am....4 months later, 5 different shops and several thousand $$ poorer when I could have simply bought the higher quality part. Instead me and several shops went chasing our tales.
 
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