My daughters Impreza ran perfect until this morning. it started like normal then a minute later it died. Started it again, 20 seconds later it died again. Didn't try starting it after that. I was told it's a bad alternator but my many years of experience working on older American cars tells me it's more of a fuel related issue. Like a fuel pump going out but I'm not hip at all on these newer computerized cars so I'm probably wrong.

 

P.S....Just in case I'm right what is the fuel pressure supposed to be on a 2013 Impresza 2.0 and how do I check it?

Could be a blocked fuel-filter.

It’s not the alternator.  Do not throw away that premium excellent high grade long life alternator for some aftermarket trash garbage that will fail in a year.  It’s probably not the fuel pump either. Okay jt could be those things but guessing is a very poor idea.

1. Scan the OBD codes. If you’re capable of asking here you’re capable of buying a $10 scanner on eBay (or $30-$50 at local auto parts store) to read codes. any National chain reads them free but of course you need to get it there. Having one is very helpful.

2. Some Subarus can flash the code for you. Not sure if a 2013 imp can.  

3. Are there any lights on the dash at all when it’s running for 20 seconds? Check engine, AT, VDC, ABS?

4.  Check the output voltage of the alternator during those 20 seconds.  Get a multimeter. Put it on DC 12 volt and one lead on alternator post and another on engine ground or battery negative. Start car and read voltage 5 seconds after it’s running but before it shuts down. What do you get?  Post the exact number here

5.  Was there any work done in the last couple of months to the engine or vehicle?

6. Any recent significant history - like it sat parked for awhile, you recently bought it, it was wrecked, battery replaced….? 

7. is everything about the key immobilizer and security system working normally and always has?

 

**** be sure to charge the battery.  these multiple starts with no run time to replenish will lessen battery life. 

Fuel pressure should be like 40-70 psi. Get a reading in that before replacing the fuel pump.

All aftermarket fuel pumps, alternators, and starters - basically any electric motor - are far inferior quality than Subaru.  They frequently fail in a matter of months. It’s not wise to replace a Subaru unit without definitive diagnosis. 

They’re unreliable enough that I’d look for a reasonable mileage used Subaru alternator for that 2013 before I’d install any aftermarket alternator. Used OEM has a very low chance of failing within a year but an aftermarket has a very real chance of doing so.  

alternator test with multimeter as I outlined above.  National auto parts stores can also test the alternator for you if you remove it snd take it to them. Subaru alternators are easy to remove. Few 10 and 12 mm bolts.

Edited November 7, 20214 yr by idosubaru

17 hours ago, idosubaru said:

Fuel pressure should be like 40-70 psi. Get a reading in that before replacing the fuel pump.

All aftermarket fuel pumps, alternators, and starters - basically any electric motor - are far inferior quality than Subaru.  They frequently fail in a matter of months. It’s not wise to replace a Subaru unit without definitive diagnosis. 

They’re unreliable enough that I’d look for a reasonable mileage used Subaru alternator for that 2013 before I’d install any aftermarket alternator. Used OEM has a very low chance of failing within a year but an aftermarket has a very real chance of doing so.  

alternator test with multimeter as I outlined above.  National auto parts stores can also test the alternator for you if you remove it snd take it to them. Subaru alternators are easy to remove. Few 10 and 12 mm bolts.

Thank you for the detailed check list. My code reader is in one of my trucks on a job in another town and wont be back for a few days but the Impreza is putting out 14.4 vdc. The car is running fine again for some reason but since it is an auction car it probably sat for a while but no idea how long and the security system seems to operate properly.

One thing I have noticed is the engine is really loud when first started and kinda loud after warmed up. Not a knocking loud or chatter loud just loud, not the exhaust, the engine. Is that normal for a Subaru or is this thing going to nickel and dime me to death?

could be some intake air component is loose, that will create noise underhood.