Technical 1.3 Diesel - P0089 and the fuel filter of doom...

[Matt Quinn]

So... following on from previous misadventure as detailed here - https://www.fiatforum.com/threads/gelled-diesel-lp-pump-now-sounds-like-a-coffee-grinder.504962/

My lift/low pressure pump has now been changed. Problems persist though. It was - 5°C at one point last night... about +2°C by the time the pump arrived and was fitted. The engine was obviously VERY cold and complained about its glow plugs. However... to cut a long story short it was eventually started (we'll deal with the glow plugs another day).

For the record - I was able to see the remaining fuel in the tank; it looked clean, clear and was definitely liquid.

The engine now runs... for a while before cutting out and throwing the check engine warning. My code reader indicates P0089 fuel reg 1 performance. - This is repeatable clearing the fault code, re-starting. - That solitary code re-occurs. I think bad fuel and/or a knackered/blocked filter could throw up that code - particularly where there is sensing on the filter itself. - But I'd be interested to hear other opinions; particularly from folk with prior experience of the 1.3 diesel engine.

It hasn't (as yet) been physically possible to re-fuel the car... so the fuel is 'not good' stuff. Bleeding the filter has been done; I noticed that loosening the bleed nipple with the engine running kills it - from experience I know this happens with some engines and not others. - Though to me this does suggest a possible lack of wonderfulness on the part of the filter. - i.e. it's basically blocked and opening the bleed is enough to kill what little pressure there is to the rest of the fuel system.

New filter is on order... should be here Saturday. It needs doing anyway.

So... my questions today...

(1) What I'd expect to be some sort of water sensor (given its position at the bottom of the filter) seems to be being referred to in some quarters as a fuel pressure sensor.

...This tutorial/video for example; https://club.autodoc.co.uk/pdf-manu...filter-on-fiat-qubo-225-replacement-guide.pdf shows a Champion CFF100502 being fitted to a Bravo 1.6. - Autodoc say this is the same procedure as applicable to the Qubo 1.3. There's a 'problem' with that video... the filter they're fitting doesn't come with the sensor already attached! - Not even from Autodoc! And yes; they do list exactly the same one for the Qubo 1.3.

So... am I right in assuming the existing sensor simply unscrews and is fitted to the new filter?

(2) What is that sensor on the bottom of the fuel filter actually sensing? Does anyone have a part number for it?

(3) I'm aware that there will be a regulator/sensor of some sort on the engine itself; where is it? and is there anything (like a strainer or something) that might need cleaning on it?

Just a quick reminder... the thing on the fuel filter I'm talking about is this: - And if you watch the Autodoc video the black thing on the bottom they refer to as a fuel pressure sensor.

 

[varesecrazy]

Hi

This isn't Qubo specific

I bought my 1st punto mj with a few warning lights on

One was fuel TEMPERATURE

The sensor that traditionally lies at the bottom of the filter and senses moisture.. Also does temperature.. According to Panda forum..

Anyway.. I bought a used filter assembly via Ebay unscrewed said sensor and put it into a new filter

Screwed it together.. Ran car for 35,000 miles. Never saw that error again

 

[Matt Quinn]

The sensor that traditionally lies at the bottom of the filter and senses moisture.. Also does temperature.. According to Panda forum..

...On a 1.3 Diesel engine?

 

[varesecrazy]

...On a 1.3 Diesel engine?

Yes!

All the 1248cc Multijet motors

But @2008..so before the DPF gubbins swapped the ancillary layout

As I think I mentioned in the other thread..

Often there are 2 or 3 filter styles on similar cars..
You want to figure out the manufacturer.. UFI is a common one

 

[Matt Quinn]

Yeah... The filter is a cannister type; exactly similar to the one shown in the Autodoc video. My car is a 2013 - so fitted with all the Euro 5 tripe etc. What I have on order is a TJ filters 51929061/71773197. - So that 'sensor' part WILL be getting switched over.

I'd really like to understand exactly what it is though and find a part number for it. - I'm finding it very frustrating that there seems to be pretty-much NO kind of workshop manual or technical information out there.

According to the parts suppliers there seem to be TWO "fuel pressure sensors" listed for the car... One that looks as if it might be the thing that screws into the bottom of the fuel filter; and 'something else' that looks more (as I'd expect) as if it's something which fits on the engine itself; on the high pressure side maybe.

 

[jackwhoo]

P0089 is a code for the fuel pressure regulator , the engine ecu controls the fuel rail pressure using the fuel pressure regulator. The ecu reads the rail pressure from the fuel rail pressure sensor.
P0089 does not necessarily mean fuel pressure regulator is faulty , it indicates that the ecu cannot control the rail pressure within limits using the fuel pressure regulator.

 

[Matt Quinn]

P0089 is a code for the fuel pressure regulator , the fuel pressure regulator controls the fuel rail pressure.
P0089 does not necessarily mean fuel pressure regulator is faulty , it indicates that the ecu cannot control the rail pressure within limits using the fuel pressure regulator.

Quite so... Which is why I'm not immediately pouncing on the regulator itself; but trying to ensure the LP side is OK before moving further into the system.

 

[jackwhoo]

Is your new lift pump pushing fuel up to filter?
Is it pushing fuel through filter?

Disconnecting pipe from filter to high pressure pump and triggering lift pump should see fuel emerge from open filter port.

 

[Matt Quinn]

Disconnecting pipe from filter to high pressure pump and triggering lift pump should see fuel emerge from open filter port.

I will try that when I get a chance... but the lift pump has to be delivering some fuel as (a) it's possible to get the engine to run for a few minutes and (b) the filter was 'bled' (as obviously I'd have introduced air into the system when I disconnected the lines at the pump end) and there was flow from the bleed nipple.

 

[bugsymike]

With the new fuel pump in tank, just turning the ignition on a few times should push the air out, but if you have someone turn ignition on whilst you open the filter bleeder it should push air out also. Once fired up with common rail system high pressure should soon clear any air from fuel.
By the way with the "waxing" issue are you sure your injectors are working fine as they may affect fuel regulator pressure error code.

 

[bugsymike]

Another thought, you mentioned vehicle standing for some time , moisture in old diesel can cause bacteria to form feeding off the diesel this will eventually block everything, you can buy biocide which helps.
Did you see anything strange when fuel tank open for pump or did fuel in tank look good?

 

[Matt Quinn]

By the way with the "waxing" issue are you sure your injectors are working fine as they may affect fuel regulator pressure error code.

They were up until the point where the -5°C cold snap (last Friday) set me along this course... the engine also runs quite well when it runs; but the real/shor answer would have to be no - I've not got that far into the system and rather hope I don't have to. - The code occurs when the engine is caused to stop by what I'm guessing/hoping is fuel starvation; it doesn't just 'pop up'. And once the engine starts to warm - well it re-starts relatively easily.

I've had cars with injector problems before; the symptoms were different - although of course we cannot yet rule them out!

The fuel and tank looked fine when I had the pump out... 'Fuel bugs' are something I'd expect to occur after many months of laying around; the car isn't used often but it is used once or twice a week on average. - The last fill (what's in it at the moment) is from October 14th.

I'll have another look in the morning; though the next step really needs to be to change that filter. It's supposed to be 2-3°C overnight (it got down to -5°C last night) and up around 4-5°C through the day. - Better weather for investigating this sort of thing.

 

[bugsymike]

I agree unlikely to be fuel bug especially as you use good fuel. We did have a guy using a strange source of cut price fuel which had that issue.
Generally I have only seen it on plant and machinery that uses red diesel and in boats left for months at a time.
Re fuel pressure does your code reader give figures, generally a minimum of around 300 Bar idling, from memory my Scudo is around 1600Bar at 3000rpm but I would need to verify that.

 

[Matt Quinn]

...Sadly no; it's a basic OBD reader - actually intended for VWs! What I'm 'questioning' in my mind at the moment is what pressure point is it actually baulking at? If that thing on the bottom of the filter is (as Autodoc and other seem to suggest) 'a' fuel pressure sensor for the LP side; is that the problem (partially chocked filter) - or is the code really being thrown up by the HP side.

In terms of diagnostic 'process' - and in the absence of any kind of manual or diagram or other information; dealing with the LP side first seems to be the only logical step. - Though is there was (say) some sort of mesh filter elsewhere; cleaning that out would also me a rational step in eliminating things.

 

[bugsymike]

...Sadly no; it's a basic OBD reader - actually intended for VWs! What I'm 'questioning' in my mind at the moment is what pressure point is it actually baulking at? If that thing on the bottom of the filter is (as Autodoc and other seem to suggest) 'a' fuel pressure sensor for the LP side; is that the problem (partially chocked filter) - or is the code really being thrown up by the HP side.

In terms of diagnostic 'process' - and in the absence of any kind of manual or diagram or other information; dealing with the LP side first seems to be the only logical step. - Though is there was (say) some sort of mesh filter elsewhere; cleaning that out would also me a rational step in eliminating things.

I think you will find the bit on the bottom of the fuel filter is most likely just a water detector, when you change the filter you swap that over to the new filter and it often has a float in it which if water present will trigger the warning. Some cars also have a heater element there, but unlikely on most vehicles.
I don't think it is a pressure regulator on the low pressure side.
So I suspect it is a high pressure sensor usually on or near the fuel rail feeding the injectors that is giving error code.

 

[Matt Quinn]

...Yup; I'd have expected it to be a water sensor. I don't think it's a pressure regulator; it's just that some sources do seem to suggest it's a pressure sensor. I'll have a closer look tomorrow to see if there's a part number on it; try and trace it from there. - I'm wondering if its purpose would be to cut the fuel pump in the event of no or inadequate LP; thus protecting the HP side from dry running; or at least minimise it.

 

[Matt Quinn]

...Having said that; it would really need to be a water detector as how else would the 'water in filter' light be triggered?

 

[bugsymike]

...Yup; I'd have expected it to be a water sensor. I don't think it's a pressure regulator; it's just that some sources do seem to suggest it's a pressure sensor. I'll have a closer look tomorrow to see if there's a part number on it; try and trace it from there. - I'm wondering if its purpose would be to cut the fuel pump in the event of no or inadequate LP; thus protecting the HP side from dry running; or at least minimise it.

My thought are it's unlikely as with common rail once pressure drops below around 230Bar it can't run anyway, unlike older diesels that injectors opened around 175 Bar from memory.
So even a slight drop of air in system it can't run.
I can't remember were you going to change the fuel filter, if so tip it out on a tray so you can see the if old fuel has any any dirt or water in it and as you swap over the sensor you could always plug it in out of the filter and see if it brings on a warning light for water in fuel when you turn it over.
I will see any more replies in morning, gonna catch some ZZZs

 

[Matt Quinn]

My thought are it's unlikely as with common rail once pressure drops below around 230Bar it can't run anyway, unlike older diesels that injectors opened around 175 Bar from memory.
So even a slight drop of air in system it can't run.
I can't remember were you going to change the fuel filter, if so tip it out on a tray so you can see the if old fuel has any any dirt or water in it and as you swap over the sensor you could always plug it in out of the filter and see if it brings on a warning light for water in fuel when you turn it over.
I will see any more replies in morning, gonna catch some ZZZs

Yup... I've had enough for the day too. Yes; there's a new filter on order - probably Saturday at the earliest before it gets here; I'll have another look tomorrow though - Might be worth taking the old filter out, emptying it and re-fitting. Thanks for the input Mike; much appreciated.

 

[bugsymike]

Yup... I've had enough for the day too. Yes; there's a new filter on order - probably Saturday at the earliest before it gets here; I'll have another look tomorrow though - Might be worth taking the old filter out, emptying it and re-fitting. Thanks for the input Mike; much appreciated.

Personally I wouldn't drain and refit old filter as a test, as it may disturb some muck which you do not want going through the rest of the system.
It was more to inspect what muck came out to see if clue to the problem.