Fuel/ battery consumption

[Tracey Axon]

Hi, hope you guys can help, I have a 2015 phev gx4, I only do about 20 miles a day and so basically been using a charge a day and very little fuel, last week my son borrowed the car and since then it is using fuel and NOT battery? Any ideas what he has done? The weather has gone very cold but I thought that would be the exact opposite and use the battery quicker? I would be very grateful for any help

 

[AndyInOz]

Most likely you've run into the 'Engine started to maintain fuel system' setup.

The car expects you to put about 20 litres through the engine every six months (maybe every 3 months in the USA).

If you only run the car on battery, the system will force you to use petrol, until you've added another 20 litres to the fuel tank.

This is to maintain the engine, seals etc. in the fuel system, and stops the fuel in the tank from going 'stale' or gelling.

It's similar to the requirement that the air-conditioner be run at least once per month.

If your tank is already full when this happens, you just have to drive around in fuel mode for a while, until you have enough space to add more. (In my case, with the low mileage I do, that took about four weeks)

I've changed my weekly errands etc. so that I use a little bit of fuel every week, and haven't seen this mode for a couple of years now.

It's possible to clear this state by disconnecting the battery for a period of time, but generally I don't recommend that owners try to second-guess the Mitsubishi engineers.

 

[Jedinsky]

Hi, hope you guys can help, I have a 2015 phev gx4, I only do about 20 miles a day and so basically been using a charge a day and very little fuel, last week my son borrowed the car and since then it is using fuel and NOT battery? Any ideas what he has done? The weather has gone very cold but I thought that would be the exact opposite and use the battery quicker? I would be very grateful for any help

every week or 2 you should run the engine for at least 15-30 minutes to prevent water accumulating in the oil, the heat drives the water out. it'll cost you maybe $3-5 in fuel per month and will prevent engine damage.

fuel goes bad because the volatiles evaporate off and this slowly reduces the octane rating of the fuel. premium fuel (higher octane rating) is the best option if you're trying to use as little fuel as possible.

the PHEV forces you to run the engine and refuel every few months because its neccesary to prevent damage caused by water infiltrating the oil and expired fuel.

 

[Raven321]

Most likely you've run into the 'Engine started to maintain fuel system' setup.

The car expects you to put about 20 litres through the engine every six months (maybe every 3 months in the USA).

If you only run the car on battery, the system will force you to use petrol, until you've added another 20 litres to the fuel tank.

This is to maintain the engine, seals etc. in the fuel system, and stops the fuel in the tank from going 'stale' or gelling.

It's similar to the requirement that the air-conditioner be run at least once per month.

If your tank is already full when this happens, you just have to drive around in fuel mode for a while, until you have enough space to add more. (In my case, with the low mileage I do, that took about four weeks)

I've changed my weekly errands etc. so that I use a little bit of fuel every week, and haven't seen this mode for a couple of years now.

It's possible to clear this state by disconnecting the battery for a period of time, but generally I don't recommend that owners try to second-guess the Mitsubishi engineers.

I just wanted to check something regarding this issue. I recently got the following message when starting my PHEV: “Consuming Old Fuel, Engine Stops After Refuelling 20L (5.3GAL) or More”

Does this mean I should just add 20L of fuel? The fuel is about 3/4 full atm. Does leaving the old fuel in there damage the vehicle in any way? Is this issue fixed by simply adding the 20L of fresh fuel?

 

[AndyInOz]

Yes, but you need to use up enough fuel to make room for the new.

Don't try siphoning fuel out, others have tried that and ended up damaging their vehicle.

 

[Raven321]

O

Yes, but you need to use up enough fuel to make room for the new.

Don't try siphoning fuel out, others have tried that and ended up damaging their vehicle.

Ok great, thanks for the quick reply. Would the older fuel just eventually be used up over time then?

 

[AndyInOz]

O

Ok great, thanks for the quick reply. Would the older fuel just eventually be used up over time then?

Yes.

Fuel thickens as it ages, and runs the risk of 'gumming up' various parts of the fuel system.

Similarly, there may be seals that rely on the fuel going past to maintain flexibility and effectiveness.

Mitsubishi engineers are trying to protect us from these issues.

Adding fresh fuel, adds more (solvents? aromatics?) to prevent this issue.

To avoid running into this, I make one longer journey once per week, where I use the engine, this means, over time, that I'm replenishing the fuel in the tank frequently enough, to avoid this fail-safe mechanism.

It's not a good idea to keep the fuel tank full unless you're expecting to need it for a longer journey. I only exceed half a tank if I make a mistake.



Note that Mitsubishi's advice is to keep weight down in the vehicle, to maximise electric range, and that is another reason for not filling the tank unless needed. (And also why the fuel tank is smaller than other Outlanders.)