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BRZ take 2-3 seconds to start and feels unresponsive below certain amount of fuel

Hello,

I have an 2015 BRZ, recently i noticed that when the fuel level drops below 3/4 the car cranks for 2-3 seconds and than starting.
(It's always starting eventually, never stalled)

I've also noticed some performance decrease in when the fuel level below 3/4.

The weird thing is that when the fuel is above 3/4 everything's just fine.

I took the car to my mechanic and we started a process of cleaning the injectors. He cleaned once, still didn't help so we scheduled to do another cleanup.

I really trust him and he's taking car of my car for a while now,

but what i don't understand is how is it possible that the issue happens only above certain fuel level (3/4) - if the problem is in the injectors.

Any help would be appreciated, Thanks :bow:

Run it up on a dyno if you can

That will tell you more than a shot gun approach, and may end up cheaper

First, try to answer some of the following. I think it will help provide people with some insight.

Any mods?

How long have you had the car? I see it is a 2015, but is this a new issue, or did you just buy the car?

How old is the battery? - A long crank is usually a sign of a dying battery.

Have you replaced the engine air filter?

Did the weather change recently and get really hot?

Are you running the AC on startup and while driving?

Are you running 93 or higher?

Did you switch to a different brand of fuel recently?

Have you tried unplugging the battery overnight and plugging it back in to reset the car?

After clearing up those basics, then I would get into injectors and other stuff.

Quote:

Originally Posted by 86MLR (Post 3238203)

Run it up on a dyno if you can

That will tell you more than a shot gun approach, and may end up cheaper

Not sure if a dyno will tell you much.
I would think it is a fuel filter issue if it is fine when the tank is full. Could be in the evap system as well though.

Edit: and what Maz said!

Quote:

Originally Posted by mazeroni (Post 3238234)

First, try to answer some of the following. I think it will help provide people with some insight.

Any mods? - no

How long have you had the car? I see it is a 2015, but is this a new issue, or did you just buy the car? - I have it around 6 months, started 2 months ago.

How old is the battery? - A long crank is usually a sign of a dying battery. - They have checked the battery, seems it's ok.

Have you replaced the engine air filter? - Yes, recently as part of 60K services

Did the weather change recently and get really hot? - It's hot, but always was :-)

Are you running the AC on startup and while driving? - not at start up, i tend to turn it off before turning off the car. While driving - yes.

Are you running 93 or higher? - 95

Did you switch to a different brand of fuel recently? - No

Have you tried unplugging the battery overnight and plugging it back in to reset the car? - i didn't but the mechanic said he's checked it and the battery is fine.

After clearing up those basics, then I would get into injectors and other stuff.

Thanks for the reply, please see answers above ^

Quote:

Originally Posted by uchiha (Post 3238249)

Thanks for the reply, please see answers above ^

I think you misunderstood the part about unplugging the battery that @mazeroni mentioned.

Unplug the battery from the terminal and leave it like that overnight. Plug it in in the morning, start the car, and allow it to idle for 10 minutes. This will allow the ECU to relearn the idle and throttle.

Quote:

Originally Posted by EndlessAzure (Post 3238305)

or you can unplug it and then stand on the brakes for a minute or so. That should drain the residual out of the system.

Quote:

Originally Posted by EndlessAzure (Post 3238305)

I'll suggest it to my mechanic when i'll take the car to the service again, thanks

If it is related to fuel level I would start with the fuel pump/inspect inside the tank.