"Low Fuel Pressure" warning message intermittently.

[Fill]

Hi all,
Just wondering if anybody has had "Low Fuel Pressure" message come up whilst driving? No other warning messages or warning lights come on and has no change in performance. Its intermittent aswell with no sort of pattern to it. Starts fine and only happens whilst driving.
The fuel filter was 18 month old and only covered 20k miles but i have replaced it again anyways. Always use shell or BP fuel and normally put Vpower diesel in once a month.
Any help would be greatly appreciated as we have a road trip coming up and want to get it sorted before we leave.
Thanks in advance.

[metalworker0]

model, year, engine size?

all the best.mark

[Fill]

Sorry, my bad!
It’s a 2019 transit custom 2.0 manual.
Thanks.

[Fill]

Diesel obviously

[metalworker0]

I don't exactly know what the dash is telling you .. as could be low on the high pressure side from the injector pump to the injectors or low on the low pressure side - from the pump in the tank to the high pressure pump.

That's what we have going on with the lack of info from the dash. hard to know.

Right now, i should be telling you to plug in diagnostic code reader and read the codes... that will give you the detail you need to know where the problem is.

Here they recommend a FREE program that you load onto a windows laptop called forscan.
its proven as the best method of diagnoses for all fords

once you established which side the fault is on, high or low side, the software will tell you the desired pressure and the actual pressure . and where it's at fault.

all the best.mark

[Fill]

I have used FORScan today and pulled DTC P008A from engine ecu. It’s saying a general signal failure on the low fuel pressure system, pressure sensor.
Looking at live data the fuel pressure looks close to the desired on the low side (nearly 5.5 bar). Trouble is it is running fine and only faults intermittently. It’s a shame the data saved when the fault occurs doesn’t show fuel pressure readings.
Think I might have to look at live data on a good run out and try and see if it will fault and then look what the low fuel pressure readings are. Guessing it could be the pressure sensor reading incorrect or a wiring issue with the term “ general signal failure” associated with the fault code.

[metalworker0]

OK it's the low side

Consists of.
Fuel lines
Pump inside the tank - often called the "SENDER" note - also has it's own mesh filter
Fuel module above tank - often called many names including relay and unit
The wiring
Fuel filter

Not to be overlooked: blockage in fuel breather system

Fuel module
Not pointing to the fuel pump relay as at fault--- its just something else to check... this is just info i picked up on it last time i looked into it,
Location on top of the tank - accessible without dropping tank
The part number is 5336501, confirmed as is located above tank on the parts diagram...fits several ford cars as well as mk8 and custom ecoblues

On ebay can be found with 5336501

Some call it a relay .. some call it a module .. some call it a unit ...that's were the confusion comes in even ford who advertise on ebay don't know what to call it .

Parts diagram calls it "control assy - fuel pump drive"

Also known as F1FA9D370GA - which is the number that is printed on the actual part

if that's at fault
Can be had for as little as £15 used - £64 from ford.

all the best.mark

[Fill]

I’m going to put FORScan on again at the weekend and have a pull and tug on wiring/connectors and see if I can replicate the fault message. Will probably give it a drive aswell to see what’s happening with live data to see if the fuel pressure on the low side is actually dropping.
I’ve replaced the fuel filter this week but still happening so can rule that out.
If there was something failing I’d expect some sort of feeling with the way the engine is running but it drives without fault. That’s why I’m wondering if it’s a bad fuel pressure sensor or a wire issue.
Thanks for the info so far Mark. Much appreciated.

[Fill]

So after a week without fault, several drives with FORScan connected looking at live data and everything looking as expected it decided to show its face again and flash up the low fuel pressure message on the dash on a normal drive ( no FORScan connected though ). There just doesnt seem to be any pattern to it. With our drive up through scotland coming up im thinking of replacing the low side fuel pressure sensor to see if it cures it. Has nobody had similar issues with this message popping up with no change in engine performance or any other warning lights coming on?

[metalworker0]

i would say with it being like that it is a wiring or multiplug fault .. this could be anywhere .. at the pcm or at the sensor or in the middle of a loom ..

if the multplugs are covered in oil, they need cleaning

sometimes the pins corrode inside -- then you need this

im sure this actual item used to be cheaper than this last year - like im sure it was £4.99 inc delivery... search other sources - amazon, temu etc .. i picked the cheapest one .. but ebay seems to be getting very expensive.

https://www.ebay.co.uk/itm/286159553541?


all the best.mark

[Fill]

Its looking more like an electrical issue somewhere given the intermittent nature with no running issue. Guess i'm going to have to trace the wiring on everything related to the low fuel pressure system and i will try some of that contact clean/lube.
Thanks for your help Mark.

[Fill]

Can anyone tell me what readings you would expect to see from the fuel pump %, fuel pump monitor % when using FORScan?
Thanks

[metalworker0]

cant find them in the manual

found pumps on ebay witrh specs

that's if you Believe the sellers info is right

50 gallons per hour

0.5 bar (7.25 psi)

google AI says something different
The low-pressure fuel pump (lift pump) on a Ford Transit 2.0 EcoBlue typically operates at approximately 4 to 5 bar (roughly 58–72 psi). The system often shows a desired pressure of around 4.47 bar, and low pressure (often indicated by fault code P008A) can cause starting issues, stalling, or hesitation

and a picture for you showing location of low pressure sensor .. no idea if fwd or rwd, number 2 on diagram

[Fill]

I can see when the fault is triggered now. The first warning with no engine running difference is when the fuel pressure isn’t being met when demanded and gradually you can see the pressure dropping to the 4.47 bar lower limit and then the spanner light comes on causing the same P008a fuel pressure fault but description is saying a component blockage or restriction.
Strange thing is we are currently driving through Scotland and the hills are no problem for the van but we cannot go over 2k rpm due to limp mode. So still providing the fuel pressure up to the high pressure pump no problem. Just not enough for the engine ecu to be happy.
I’m wondering if the controller is at fault, the pump is getting weak or there is a blockage at the pickup on the pump.
You can see the pump is working and % rate is changing but then goes to a fixed 46.99% when the fuel pressure is starting to drop.
I’ve changed the fuel filter and the low pressure sensor and not sorted it.
Have heard that the high pressure pumps can break up and leave particles in tank which caused restrictions but on higher mileage vehicles.

[Fill]

And it generally starts after about 45 mins of driving now.