Technical Car Stops while driving With Mesage Engine oil pressure low

[Badal]

Hello,
I have a problem in my car that it stops suddenly witha message on screen showing engine oil pressure low.. When I fill petrol to nearly 75% of the tank then car runs smoothly, and if fule level goes to nearly 60% of the tank capacity the problem starts. This problem is worse when the outside temperature is high (may be above 30°C) I have changed engine oil and oil filters recently.... But this problem is still coming and I always need to keep the fuel tank full... Any help please

 

[GrandePunto PL]

So it's more electrical problem. Wires, corrosion, bad contacts. Bad "earth/ground" somewhere.
Study the schematic/diagram and find common denominator (what the fuel level has to do with ECU and the oil pressure switch - not much).

Oil switch K30 is managed by ECU: https://aftersales.fiat.com/elearnsections/main.aspx?nodeID=199008213&languageID=2&markID=1&modelID=199000000&valID=199000001&prodID=199000000&modelName=Fiat - 199 - Grande Punto&langDesc=English&sectionName=Impianto Elettrico&validityName=1.4 8v

N040, fuel pump and level sensor is managed by BodyComputer: https://aftersales.fiat.com/elearnsections/main.aspx?nodeID=199008463&languageID=2&markID=1&modelID=199000000&valID=199000001&prodID=199000000&modelName=Fiat - 199 - Grande Punto&langDesc=English&sectionName=Impianto Elettrico&validityName=1.4 8v

Every time the problem is oil related, check the oil pressure, ideally while driving (with the switch in place: ECU needs this signal to CHANGE after start).

Video is from cold to hot engine, old oil. Pretty dramatic change in pressure at idle (from 4 bar cold, to barely over 1 bar when very hot). Relief valve is setup to 5 bar as we can see.

 

[Badal]

But this problem appears only when it's very hot temperature outside, and after maintaining fuel level it disappeares, when I showd to garage, the technician told me it's the problem of fuel tank gets air and aom other technician says that the file cap is faulty it may not be passing the air out of fuel tank so the problem is happening ... Can it be the problem with fuel tank ???

 

[Badal]

I would also like to add that the problem doesn't come while driving at night time, I can drive easily till the fuel meter needle dropping to the more than half of the bottom red line

 

[Redeagle]

Hello,
I have a problem in my car that it stops suddenly witha message on screen showing engine oil pressure low.. When I fill petrol to nearly 75% of the tank then car runs smoothly, and if fule level goes to nearly 60% of the tank capacity the problem starts. This problem is worse when the outside temperature is high (may be above 30°C) I have changed engine oil and oil filters recently.... But this problem is still coming and I always need to keep the fuel tank full... Any help please

Possibly the pick up is blocked or oil filter?

 

[Badal]

Possibly the pick up is blocked or oil filter?

Oil and oil filters changed recently, whatvis pickup block?? I actually have no problem of pickup in my car, but this problem comes when petrol level decrease and especially in hott weather... I can't drive car till reserve of fuel

 

[GrandePunto PL]

WHY are you "fixing" the car, not mechanic/"technician"? You clearly have no clue of what to do, you have no proper tools etc.
You're just not prepared/equipped to tackle this problem, I guess. Straight technical fact (not "personal attack").
Fuel level has nothing to do (mechanically) with the oil pressure! It's possible electrically (bad power, "ground" somewhere etc.).
Or you have two separate issues (fuel and lubrication system, plus electrical fault maybe)...manifesting at the same time.
Fuel tank venting/breathing and EVAP system (link) can be spoiling fuel delivery, making engine weaker, but tripping "oil pressure" fault? No.

Ultimate advice: if you can't check oil pressure and the switch operation, fuel pressure (and venting issue - when the problem occurs, open the fuel cap, see if it helps), electrical connections, which are BASICS (fundamental checks) - take this car to the mechanic (especially if you don't understand what is blocked oil pickup or leaky, sucking some air). Easy and fast solution.

Fuel pressure, test drive.

This is very simple car. There is no "mystery" at all. No one should struggle to diagnose and fix Fiats (especially simple FIRE family units).

 

[Redeagle]

Oil and oil filters changed recently, whatvis pickup block?? I actually have no problem of pickup in my car, but this problem comes when petrol level decrease and especially in hott weather... I can't drive car till reserve of fuel

Lol pickup is the filter before the oil pickup from the sump to the engine
It's usually a mesh screen in the sump

 

[ZaphodB]

I'd check engine earth strap and voltage regulation of alternator just to rule them out /

 

[Mike1alike]

You're problem is the crankshaft positioning sensor. It is broken and only works when it is cold. When it gets hot it stops sending signal to ECU and so, the ECU "thinks" the engine is not revolving therefore it cuts the fuel injection to engine. You can mesure the CPS cold and hot or you can just buy a new one and replace it.
The observations and correlations you and garage technician made are just stuff, they don't affect in any way the problem you have, the engine doesn't stop because of that.

 

[Mike1alike]

And the low oil pressure error gets recorded because engine stops having the fuel cut off, but ECU and everything remain powered on, as you don't turn off the key. Readings made in those moments make the error to be recorded.

 

[Badal]

WHY are you "fixing" the car, not mechanic/"technician"? You clearly have no clue of what to do, you have no proper tools etc.
You're just not prepared/equipped to tackle this problem, I guess. Straight technical fact (not "personal attack").
Fuel level has nothing to do (mechanically) with the oil pressure! It's possible electrically (bad power, "ground" somewhere etc.).
Or you have two separate issues (fuel and lubrication system, plus electrical fault maybe)...manifesting at the same time.
Fuel tank venting/breathing and EVAP system (link) can be spoiling fuel delivery, making engine weaker, but tripping "oil pressure" fault? No.

Ultimate advice: if you can't check oil pressure and the switch operation, fuel pressure (and venting issue - when the problem occurs, open the fuel cap, see if it helps), electrical connections, which are BASICS (fundamental checks) - take this car to the mechanic (especially if you don't understand what is blocked oil pickup or leaky, sucking some air). Easy and fast solution.

Fuel pressure, test drive.

This is very simple car. There is no "mystery" at all. No one should struggle to diagnose and fix Fiats (especially simple FIRE family units).

Thank you for your valuable time, but I am not fixing the car myself... I am just wondering from one garage to another as in our area there are no specialist mechanics of this wonderful car and Fiate authorised service center is also not available here... So different mechanics tells different stories but issues are still pending... I am on this forum to get some knowledge so that I can share with technicians to understand the problema and solutions.... I really don't want to sell my car because this is really wonderfull... But there are so many problems in car that mechanics here are unable to understand and just doing trial and error work.... So this way it's getting to costly to maintain it

 

[Badal]

Thank you for your valuable time, but I am not fixing the car myself... I am just wondering from one garage to another as in our area there are no specialist mechanics of this wonderful car and Fiate authorised service center is also not available here... So different mechanics tells different stories but issues are still pending... I am on this forum to get some knowledge so that I can share with technicians to understand the problema and solutions.... I really don't want to sell my car because this is really wonderfull... But there are so many problems in car that mechanics here are unable to understand and just doing trial and error work.... So this way it's getting to costly to maintain it

And I still don't understand that if the pickup failure is there,oil pressure problem is there or may be cranckshaft sensor problem is there as one member mentioned in this thread.... Why the problem disappear after topping up the fuel????

 

[Badal]

I'd check engine earth strap and voltage regulation of alternator just to rule them out /

I have changed the earth strap, and also attached extra earth cable to engine tray

 

[portland_bill]

Hello,
I have a problem in my car that it stops suddenly witha message on screen showing engine oil pressure low.. When I fill petrol to nearly 75% of the tank then car runs smoothly, and if fule level goes to nearly 60% of the tank capacity the problem starts. This problem is worse when the outside temperature is high (may be above 30°C) I have changed engine oil and oil filters recently.... But this problem is still coming and I always need to keep the fuel tank full... Any help please

I wonder if you are chasing the wrong issue. What happens first, the engine stops, or the oil pressure message? The oil pressure warning light should illuminate at around 5psi, even with the engine still running. Does this happen, or only after the engine has stopped?
If the engine stops, for whatever reason, other than by switching it off, (such as a stall, or loss of fuel pressure) the electrics are still live, and expecting it to be running. But once stopped, the oil pressure will be zero, so that warning will pop up. The oil pressure warning may be nothing to do with the engine stopping, just a result.
You need to be very clear about what happens, in what order, even if almost simultaneously.

There should be a breather system for the fuel tank, usually with blue pipes. This holds fumes from fuel evaporation, preventing them escaping to atmosphere. These are then vented to the engine intake by an electronic valve, usually situated in the engine compartment. If this valve opens at low engine speeds, it can allow too much air in, causing a weak mixture and a stall. If the tank breather system has a leak in its pipework, extra air can be admitted. Operation of this valve and system needs checking, or perhaps just disconnecting the valve for a test period. Check the pipes carefully for cracking or poor joints. If suspect, spraying something flammable, like WD40 or brake cleaner near the suspected leak will cause the engine note to change if it is sucking in.

Could the fuel pump in the tank be getting hot and failing? With more fuel in the tank, there is a greater heat sink. As fuel level drops, the heat has nowhere to go.

 

[Badal]

I wonder if you are chasing the wrong issue. What happens first, the engine stops, or the oil pressure message? The oil pressure warning light should illuminate at around 5psi, even with the engine still running. Does this happen, or only after the engine has stopped?
If the engine stops, for whatever reason, other than by switching it off, (such as a stall, or loss of fuel pressure) the electrics are still live, and expecting it to be running. But once stopped, the oil pressure will be zero, so that warning will pop up. The oil pressure warning may be nothing to do with the engine stopping, just a result.
You need to be very clear about what happens, in what order, even if almost simultaneously.

There should be a breather system for the fuel tank, usually with blue pipes. This holds fumes from fuel evaporation, preventing them escaping to atmosphere. These are then vented to the engine intake by an electronic valve, usually situated in the engine compartment. If this valve opens at low engine speeds, it can allow too much air in, causing a weak mixture and a stall. If the tank breather system has a leak in its pipework, extra air can be admitted. Operation of this valve and system needs checking, or perhaps just disconnecting the valve for a test period. Check the pipes carefully for cracking or poor joints. If suspect, spraying something flammable, like WD40 or brake cleaner near the suspected leak will cause the engine note to change if it is sucking in.

Could the fuel pump in the tank be getting hot and failing? With more fuel in the tank, there is a greater heat sink. As fuel level drops, the heat has nowhere to go.

Let me clear this.
First of all engine stalles and then stop at sudden, after that oil pressure low message appears, no warning light come at all.... When I open the fieltank lead and drive keeping the open, I can drive few miles but until I refuel I can't go longer. This problem happens only in hot weather and day time... At night time evrything seems perfect

 

[Mike1alike]

Why the problem disappear after topping up the fuel????

That is just a coincidence. What actually happens is that crankshaft positioning sensor gets cooled down in the meantime and that's why the problem disappears. But you can very easily check and make sure the CPS is the problem, like this: when the engine stops and can't fire up, while you crank it watch the RPM gauge. If it goes up to ~200 means the CPS is good. If it stays stucked to 0 means the CPS is faulty.

 

[Zardo]

Reading OBD-errors would help.

 

[Mike1alike]

It would, if there are stored errors that reappear after cleaning them. With faulty CPS reading errors doesn't help because there are none stored. The sensor is still "alive", it just sends wrong signal to ECU, causing engine to stop. This detail makes this problem very difficult to identify the real fault for some people and many times they just wrongfully tackle it replacing other parts. That's why is very good to always remember "If engine stops when it is getting hot, first thing to check is the crankshaft positioning sensor".

 

[Zardo]

It would, if there are stored errors that reappear after cleaning them. With faulty CPS reading errors doesn't help because there are none stored. The sensor is still "alive", it just sends wrong signal to ECU, causing engine to stop. This detail makes this problem very difficult to identify the real fault for some people and many times they just wrongfully tackle it replacing other parts. That's why is very good to always remember "If engine stops when it is getting hot, first thing to check is the crankshaft positioning sensor".

How does this explain the engine oil low pressure warning message? Is the ECU still getting signals as if the engine were running? But it's actually not?