Breakdown - P0191 Fuel Rail Pressure Sensor

[shamirj]

Travelling just cruising and suddenly no power, car came to a complete stop, D4 2011 Tdv6 got towed out got car home, hooked up the icarsoft reader to find error code PO191 = fuel rail pressure sensor range/performance. Assume this maybe the low or high pressure fuel pumps from my readings, now have to wait till after new year when mechanics are all back to work. bummer.

two dash lights are always on, i can manipulate the vehicle to crank over but that's all, just cranks no start. anything i can try at home???

[josh.huber]

You might get lucky with a rail pressure sensor. That code you read should have a dash number p0910-23 example. The dash number relates to the type of failure. Example voltage above threshold etc

[shamirj]

1. pretty sure this is the fuel sensor worth changing at approx $100 ex UK but they come in two thread types thin and thicker apparently so in order to order a new one i needed to remove my old one. removed all bits n pieces for better access.

2. spanner does not fit, tried all types of spanners but the closest is this 1/2 inch which is still not the correct size, that damn nut is so tight unable to move it at all.

packed up for today will look at it tomorrow, need a diff size spanner yet thin enough to give me access. any suggestions please

[josh.huber]

That spanner is 1/2 Whitworth, which from memory is about 19mm . Yes they are tight they are generally a tapered thread for fuel rail pressure. Like npt air lines. They usually put a bit of high pressure sealant on them in the factory which sets better then super glue

[scarry]

That spanner is 1/2 Whitworth, which from memory is about 19mm . Yes they are tight they are generally a tapered thread for fuel rail pressure. Like npt air lines. They usually put a bit of high pressure sealant on them in the factory which sets better then super glue

Best place to find Whitworth spanners is the local markets.
They are difficult to get from the usual places at times.

[Graeme]

The size will be metric, not Whitworth and that spanner has been modified so the Whitworth size isn't much of a guide.

[shamirj]

1. got the hammer and chisel onto it this morning and managed to get it out that way. finally... funny thing is there was no fuel (diesel) pouring out of this opening surely the rail should be full of diesel and some should of poured out. thinking now might be another issue such as the low press fuel pump in the tank but have ordered a new sensor to try that first from the UK

2. said sensor come in two diff thread sizes this is the thicker thread 55PP19-02 the other one fitted are the 55PP19-01 which has the thinner thread. Now to wait for the replacement part to arrive from Uk approx $130 and see if this solves my problem or whether i need to drop the tank.

i could crank her over to see if diesel squirts out of the remaining hole where the sensor fits, that should tell me if the intank pump works or not?

[shamirj]

Just tested by cranking over the engine, only a very small amount of diesel came out of the sensor opening, i would of thought this should be under immense pressure and diesel would squirt everywhere but it didn't so not sure what to make of this, whether that's normal or i have a faulty pump in the tank or another issue blocking fuel supply to the rail.

[josh.huber]

There is a shraeder valve on top of the engine. You can put an improvised gauge on there. I suggest buying the manual to find out required pressures.

[BradC]

Just tested by cranking over the engine, only a very small amount of diesel came out of the sensor opening, i would of thought this should be under immense pressure and diesel would squirt everywhere but it didn't so not sure what to make of this, whether that's normal or i have a faulty pump in the tank or another issue blocking fuel supply to the rail.

You're conflating volume with pressure. The HPFP can generate huge pressures, but it's limited in volume. The HPFP can (at absolute best) generate 0.8ml per revolution. It's geared at ~5/6 of the crank speed so even if you were cranking at 300RPM it'd pump 200ml/minute at best. That's with both valves wide open, which they aren't when cranking. 3.3ml/second through a hole that size isn't going to "squirt" anywhere. More like a prostate constrained dribble.

If you can beg, borrow or steal a low pressure gauge you can test the low pressure pump at the schrader prior to the HPFP. The LPFP is rated at ~70L/hr and ~0.5 bar (~7.xPSI). If you see anywhere vaguely near 1L/minute and > 3psi at the schrader then it's not the LPFP causing your no-start.

If you had a valve core removal tool you could pop the core from the schrader and put a bit of hose over it to time the delivery volumes. You really need a gauge to check the pressure, but frankly I can run my TDV6 with the LPFP fuse removed, so it's not likely that is the issue.

These figures are all based on a 2.7L TDV6 in a D3, but there close enough to the D4 to provide diagnostic assistance.

[loanrangie]

Check the pump belt hasn't snapped.

[shamirj]

you talking about the HPFP belt at rear of the engine which is almost impossible to get at or is there another belt you are referring to?

[Tombie]

you talking about the HPFP belt at rear of the engine which is almost impossible to get at or is there another belt you are referring to?

He is. It’s not impossible to get at. Take a look in the Good Oil; I think there’s a write up on changing it with body on that will help.

[loanrangie]

Correct amundo.

[RANDLOVER]

…………………………………. but frankly I can run my TDV6 with the LPFP fuse removed, so it's not likely that is the issue.

These figures are all based on a 2.7L TDV6 in a D3, but there close enough to the D4 to provide diagnostic assistance.

Pray tell us more, as I actually bought a spare LP pump (they didn't seem to be an off the shelf item) as I could hear mine whine sometimes on cold mornings in the garage which worried me. I hate these single point of failure things. On
my D2 TD5 I had an external one fitted, like the ones used on Bowler's. I actually rang Drew Bowler for the details, he was very helpful, a nice guy, unfortunately he has passed away now. The external pump also became noisy, making a whine when I test ran it every so often, I discovered that I could just use it for priming, then switch it off, as the cam driven injectors would suck the fuel through the pump, had to keep the rev's up though, which I found was quite fun, as involved more driving skill.

Am I to understand that the HP/Injector pump will suck fuel from the tank through the LPFP, much like the above arrangement?

Cheers,
Randy

[BradC]

Pray tell us more

....
Am I to understand that the HP/Injector pump will suck fuel from the tank through the LPFP, much like the above arrangement?

Yep. Not saying I recommend the practice, and it did set a fault code (although no visible indication of it) when I really planted the boot, but I drove it around the block a couple of times with the LPFP fuse out while monitoring the pressures at the schraeder (not surprisingly a fairly good vacuum when getting the right boot down).

I did it as part of my "fairly extensive and masochistic" diagnostic prior to replacing the HPFP to prove the fault wasn't caused by a blocked fuel filter or dicey LPFP. The reason I would not recommend the practice is it can cause cavitation in the feed pump and that could well lead to more extensive damage to the HPFP, but mine will certainly start and run at nearly full noise with the LPFP not functioning at all.

The HPFP is 2 pumps in one. It's a brass vane feed pump coupled to (and feeding) the triple piston high pressure pump. The VCV controls the volume of fuel going to the piston pump by bleeding fuel from between the two pumps back into the input of the feed pump.

The LPFP serves a few roles.
A) The pressure regulator in the tank bypasses a significant amount of its output which is used to operate the scavenging venturi in the tank to ensure a reliable fuel supply at most sane angles of operation and diesel levels.
B) It ensures positive pressures as the fuel filter progressively impedes flow
C) By keeping a positive pressure at the input of the HPFP it ensures the system is mostly self bleeding
D) By keeping a positive pressure at the input of the HPFP it inhibits cavitation in the feed pump

When properly primed up, the vane feed pump could comfortably suck a golf ball through a straw, so with insufficient pressure on its input it'll boil diesel nicely.

If all the stars are in perfect alignment, your tank is full, filter is clear and all the pipes are nicely open you should be able to pootle around town with no LPFP, with the caveat you might well be damaging the HPFP.

Put a gauge on it and make sure it's working. I see a vacuum on mine at full noise, up hill in third gear. Pretty much at all other times there is a positive pressure (albeit sometimes it's quite small).

All that is to say that provided you have fuel in the tank and a relatively clear filter, a non-functional LPFP should not be the cause of a no-start.

[goz007]

have u checked the fuel filter? when was the last time the fuel filter was replaced?

[shamirj]

doubt its the fuel filter that was just done in last 1000kms. my bet is it could be the hpfp belt but unlikely even though its had 100,000kms on it without a timing belt change as yet. more likely to be one of the two fuels pumps possibly the one in the tank at a guess if my sensor is cleared of faults. just waiting on the delivery of the new sensor but have doubts even this is the problem. it was worth a shot replacing this part. will report back once new sensor fitted re outcome but guessing it wont cure my problem...

[shamirj]

got the new sensor for the fuel pressure line and fitted which made no difference, still will not start. cranks but does not start.

thinking now it has to be either of the two fuel pumps, either the cheaper pump in the fuel tank, or the more expensive pump in rear of engine. the HPFP belt could also be snapped but unlikely to me.

upon ignition on, there is no fuel pump noise or any evidence the pump is actually pumping fuel through the system, my guess is that is the role of the LPFP in the tank? based on this i think it might be the in tank fuel pump that has died.

upon further investigation with my code reader, the fuel pressure in the rail was found to be 'high' which kinda doesn't make sense to me if the pump is dead. Could there be some other explanation as to how could the system have higher then normal readings for the pressure in the fuel lines. This was the code read from the hand held car reader. looks to be a tow to the mechanic to sort out as i have no idea.

[DiscoJeffster]

Good luck. Money on it’s not the LPFP.

[BradC]

got the new sensor for the fuel pressure line and fitted which made no difference, still will not start. cranks but does not start.

thinking now it has to be either of the two fuel pumps, either the cheaper pump in the fuel tank, or the more expensive pump in rear of engine. the HPFP belt could also be snapped but unlikely to me.

upon ignition on, there is no fuel pump noise or any evidence the pump is actually pumping fuel through the system, my guess is that is the role of the LPFP in the tank? based on this i think it might be the in tank fuel pump that has died.

upon further investigation with my code reader, the fuel pressure in the rail was found to be 'high' which kinda doesn't make sense to me if the pump is dead. Could there be some other explanation as to how could the system have higher then normal readings for the pressure in the fuel lines. This was the code read from the hand held car reader. looks to be a tow to the mechanic to sort out as i have no idea.

Have someone depress the valve on the schrader in the engine bay and turn the key on. You should get 20(ish) seconds of good diesel flow if the low pressure pump is working at all.
There is a fuse and relay for it in the engine bay fusebox, but I can't help much further than that as I have D3. The wiring diagram is pretty straightforward though.

If you don't get fuel then I'd be looking at bypassing the fuse & relay with a jumper wire as a check first. Could also be the connector or associated wiring harness. I've heard of one that even had a rat chew the harness, but that manifested issues with the fuel gauge as well.

You can get a high pressure code if the PCV jams closed. A sticky PCV is one of the reasons for HPFP failure, although sticking open (low pressure) seems to be more common. I manually generated a high pressure code by jamming the PCV closed with a battery while testing. I got the engine running but it didn't like it much. Probably not one of the brightest things I've done. It did show the valve was working though.

If you have the 2.7 V6 I'd have thought you should be able to crack the top of the belt cover and have a look in with a mirror or have a feel about. That'd tell you if it was the belt that went. The fact you said you had fuel while it was cranking (even though it wasn't a lot) might indicate otherwise though.

[shamirj]

assessment has come in, fuel contamination...

[BradC]

assessment has come in, fuel contamination...

So HPFP and potentially injectors?

[theelms66]

MMM with what?

[shamirj]

fuel came back very cloudy diesel. off to the experts to have the sample of fuel tested, lodged an insurance claim and still with the mechanics doing a full report on whats needed to be fixed incl but not limited to two fuel pumps and injectors as a minimum. just have to wait it out now. positives are will be a great tourer once more with two new fuel pumps, my timing belts were due anyway so will get them to do the rear belt as they do the pump. funny thing was the exact same thing happened to a mate with a RRS and they replaced his HPFP which he later sold and replaced with an Audi 4wd which i think he regrets now. he had 10yrs with his rangie no problems.

[shamirj]

insurance company had fuel tested and yes its common to have contaminated fuel in sydney according to the insurance assessor.
approval rec'd for works to be carried out including the following; total cost of repairs $17500 of which approx $3000 is labour costs.
items replaced include fuel injectors 6k, fuel pipes, fuel rails either side 1k, HPFP over 2k, timing belt rear, tank fuel pump $600. Parts come in at over 12k. big job to complete and will be getting the front timing belt done at my cost. now the wait till the car returns home. Looking forward to getting my LR back. Never experienced fuel contamination before only ever heard of this in the bush with older petrol stations or older tanks. I think there was also talk from the assessor to write off the vehicle but thank the lord we have approval for the repairs instead.

[INter674]

OMG is there any way of tracing the supplier...they should be made to pay! !

Fuel in Aus is a total rip off without this sort of crap outcome on top😐

And....How do avoid it happening again?

[letherm]

insurance company had fuel tested and yes its common to have contaminated fuel in sydney according to the insurance assessor.
approval rec'd for works to be carried out including the following; total cost of repairs $17500 of which approx $3000 is labour costs.
items replaced include fuel injectors 6k, fuel pipes, fuel rails either side 1k, HPFP over 2k, timing belt rear, tank fuel pump $600. Parts come in at over 12k. big job to complete and will be getting the front timing belt done at my cost. now the wait till the car returns home. Looking forward to getting my LR back. Never experienced fuel contamination before only ever heard of this in the bush with older petrol stations or older tanks. I think there was also talk from the assessor to write off the vehicle but thank the lord we have approval for the repairs instead.

Obviously without naming and shaming but which suburb or area did you buy the fuel from?

Martin

[DiscoJeffster]

Obviously without naming and shaming but which suburb or area did you buy the fuel from?

Martin

What’s the relevance?

[RANDLOVER]

Yep. Not saying I recommend the practice, and it did set a fault code (although no visible indication of it) when I really planted the boot, but I drove it around the block a couple of times with the LPFP fuse out while monitoring the pressures at the schraeder (not surprisingly a fairly good vacuum when getting the right boot down)…………..

…………………………….
All that is to say that provided you have fuel in the tank and a relatively clear filter, a non-functional LPFP should not be the cause of a no-start.
[/LEFT]

Brad Looks like your theory has been proven correct in real world circumstances.



……………………………..
The other occasion was most recently when the in tank pump failed, but we were still able to roll along at 70kph for 250k's on the injector pump pulling enough fuel to get us to Kalgoorlie...…….

[letherm]

What’s the relevance? To avoid buying fuel in that area.

[DiscoJeffster]

To avoid buying fuel in that area.

“Area”. So every station in the area is tarnished with the same brush because of one incident?

Is the issue a tank issue at the premises, a batch issue that could affect more than one? And has the bad batch gone by now?

Etc. If you don’t name the place then it’s pretty pointless. At the very least you might avoid one site in a town but more than that .....

[letherm]

“Area”. So every station in the area is tarnished with the same brush because of one incident?

Is the issue a tank issue at the premises, a batch issue that could affect more than one? And has the bad batch gone by now?

Etc. If you don’t name the place then it’s pretty pointless. At the very least you might avoid one site in a town but more than that .....


So every station in the area is tarnished with the same brush because of one incident?
No, but it does mean that you will avoid the one that did sell bad fuel.

Is the issue a tank issue at the premises, a batch issue that could affect more than one? And has the bad batch gone by now?
Don't know so I would prefer not to take the chance.

Etc. If you don’t name the place then it’s pretty pointless. At the very least you might avoid one site in a town but more than that .....
Which is why I asked about suburb/area to avoid which is sufficient in and of itself to mitigate the risk of getting a bad tank of fuel. I agree that if you're in a small town it's a waste of but I'm not and have the option to go elsewhere if I want to.

[RANDLOVER]

Might not have been a bad batch, as there is also the theory of not buying fuel after a tanker delivery, as that stirs up all the sediment and water in and underground tank.

[Tombie]

Avoiding a suburb to avoid bad fuel is statistically not viable.

What was good today can easily be bad tomorrow depending on the root cause.

Best “rule of thumb” is to buy from high turnover stations of known brands. Obviously this can’t stop bad fuel either but fresh fuel is more likely to be in their tanks.

Just don’t fuel up straight after the tanker has been sitting there, at this time all the sediment is stirred up.

[vbrab]

Avoiding a suburb to avoid bad fuel is statistically not viable.

What was good today can easily be bad tomorrow depending on the root cause.

Best “rule of thumb” is to buy from high turnover stations of known brands. Obviously this can’t stop bad fuel either but fresh fuel is more likely to be in their tanks.

Just don’t fuel up straight after the tanker has been sitting there, at this time all the sediment is stirred up.


It seems so obvious, that knowing the cost of repairs on modern diesels from contaminated fuel, that fuel companies would be putting in some sort of filtration/alert system that would either filter fuel or alert when contaminated.
Such a system would not be that expensive to add to their fuel dispensing, and might even attract diesel users if they had some level of assurance that fuel was "clean".
Had a situation in Port Hedland where a local station had extreme water contamination every time it rained.
Not only did they knock out about 60 vehicles, they also disabled all the towns ambulances.
That station eventually sold so little diesel they had to install new tanks to lure customers back, with most of us just shopping elsewhere after that anyway.

[loanrangie]

I had this error P0191-24 last week after doing an oil/filter change, must have knocked the sensor sideways a little so it didnt stand out as being the issue.
After getting the code i googled it which of cause led me back to the forum, i didnt even know where the sensor was until i remove the engine cover and saw that red connector sticking out like dogs bollocks.