Failure to start, don't think it's the alternator or battery

[Tundra_Sniper]

Hi Guys this is my first post, so glad to be here. Second year tech in the heavy diesel mechanics program at UAA Anchorage. I haven't taken electrical yet, so I am feeling my way along here. 2001 Forester with issues starting. Yesterday and the day before it had a problem starting, then next try it fired up. Late yesterday wouldn't start, jumped with a truck. Voltage @ batt engine idle was 14.2-14.4v. Engine off 12.8v. I believe I am improperly using my i400 Amp clamp and cannot get a reading to confirm the necessary 70 or so amps in B+ @ alternator. Today it would roll start fine. Now a roll start will not work. I am inclined to believe the battery and alternator are fine. I am led to believe perhaps ignition coil? I don't know a helluva lot though yet, and from the bit of reading I've done so far, I'm not inclined to mess with this just yet. (It's a step-up transformer, and could kill the crap out of me right?) so I want to get some counsel from you guys before I proceed. Thanks 

 

-Dan in Alaska

[john in KY]

Not clear what you mean when you state the engine will not start. Do you mean the engine cranks but will not start or do you mean the engine will not crank? Always a good idea to first clean the battery terminals.  And welcome. 

[Tundra_Sniper]

Update: 

So John two days ago, (at a campsite deep in the Alaskan woods where nobody knew I was, yeesh) turned the key in ignition, and it turned over once, and then a buzzing noise. Waited a second, tried again and it fired up and drove away. Did the same thing the next afternoon. That same day, at night, I turn key in the ignition, and a buzzing, no click. It jump starts, and I drive home. Today it wont start, so I do my check and voltage is as stated above, and I roll start it a few times in second gear. Main fuse is not blown, after eventually it fails to roll start OR jump start. My shop teacher and job foreman told me that, due to turning key in ignition both step one and two, the lights got much dimmer, that it almost certainly made the battery the culprit, as weak, and that my 12.8V reading may be misleading due to an internal short in the battery, between cells.  As a side note, shop foreman told me there was the possibility of breaking the timing chain doing a few repeated roll starts, downhill, as I did, additionally, I have to admit pulling a boner, I was running my DMM on amperage, with pos lead to B+ terminal on the alternator, and the negative lead to the frame of vehicle and it killed the engine. Not sure here, if that may have rendered damage. Update complete. (running jumpers right now to try and charge up and start car.) Also, not sure why, if it's just the battery that's dead, I cannot roll start the vehicle again. 

[john in KY]

Modern engines will never roll start with a dead battery. You need a battery to power the ECU/fuel pump/injectors/etc. Since it won't start/crank with a jump, I'd eliminate the battery as the problem. Have you cleaned the battery posts and the the battery wire clamps? Lots of corrosion equals lots of resistance. The starter may be failing but Subaru starters are tough as I have never had one fail on me. 

[heartless]

My shop teacher and job foreman told me that, due to turning key in ignition both step one and two, the lights got much dimmer, that it almost certainly made the battery the culprit, as weak, and that my 12.8V reading may be misleading due to an internal short in the battery, between cells.

 

How old is the battery? most are only good for 4 or 5 years - less in extreme weather conditions.

 

Most chain auto parts stores will test the charging system for you for free, but if you are having issues with it starting at all, you could pull the battery out and take it in to be load tested. I would recommend getting the alternator checked out as well. bad batteries can kill an alternator (over working it), and vice-versa.

[1 Lucky Texan]

re-fresh the contacts/plunger in the starter?

[Tundra_Sniper]

swapped out battery and it starts the other subaru just fine. So now I'm starting to think it could be a starter motor? Boss says possibly a neutral start switch. 

[1 Lucky Texan]

next time it doesn't start, whack the starter with a piece of wood. Not like swinging to clear the stands, maybe start with a 'bunt', then try for a single.

 

If it starts, probably need to rebuild the solenoid - common repair. Might not make sense though if it doesn't push start....?

 

There's a clutch switch that can go bad - not sure you'd get that buzzing though....?

 

 

some outbacks and legacies in that year range have problems with their fuel pumps but, I think the Impreza chassis are different?

Edited August 5, 2014 by 1 Lucky Texan

[Tundra_Sniper]

I was starting to get a hardon for having a nice complicated electrical diagnosis that would make me feel smart when I figured it out. Unfortunately, I had to shave a layer of lead off the battery terminals (ok not really). Cleaned up the conns a little more deeply and no problems.  At least I got to read some fancy diagrams and learn more about the ignition and charging systems.