My 2003 H6 failed to start the other day.  It turned over and fired for a fraction of a second and then just cranked with no attempt to fire at all.  I checked the oil and it was at the low line so I filled it up.  It still would not start, but after craning for 10-15 seconds several times it started to fire roughly and then began to run fine.  It's been running perfectly ever since.  I was wondering if there was some kind of low oil sensor that was kicking in but see nothing about that.  There were no codes thrown when it was failing to start or after.

Any idea what this might have been?  Wouldn't like to be stranded anywhere if it happens again.  Thanks.

Edited December 17, 20205 yr by dburton97128
fix year

No low oil sensor that would impact the start.  Sounds more like a fuel delivery problem.   Did you hear the pump run when you turned the key on?  Might want to check fuel pressure as well.

If my memory is correct, your fuel pump has a metal cap on it and sometimes the cap/oring fail.  Search the USMB.

Was it exceptionally cold that day? How many miles are on it? How's the maintenance been (specifically, spark plugs)?

 

And then yea, I'd be inspecting that fuel pump cap: https://www.subaruoutback.org/threads/symptoms-of-fuel-pump-o-ring-problem.41182/

Edited December 17, 20205 yr by Numbchux

battery or cables/terminals weak?

any check engine lights?

fuel cap broken cap tab.  replace the cap and oring.  you're better off just keeping your OEM pump and replacing the cap and oring on it than buying an aftermarket one.  you can preventatively check the cap now for a crack right at the tab that holds it to the base of the fuel pump.   or just have a spare cap and oring on hand - I used to keep one in the glove box when i drove these cars.  it's common enough it's worth checking if you're worried about it. 

 

Not a spark plug problem, sparks plugs don't fail all at once like this.  Could have been total absence of spark, maybe coil or something, but I would have thought I would get a code for that.  Check engine light on but that is expected when the engine is not running.  Goes out a few seconds after starting.   It was not particularly cold.  ~125,000 mi.

I'll look into the fuel pump cap issue.  Does sound like that could be it.  I'd like to identify exactly what parts my car might need before opening it up.  Hopefully can figure that out from that thread.  BTW this is actually a 2003, not 2004.

Thanks.

Edited December 17, 20205 yr by dburton97128
update year

I can't speak to its quality, but I might have tried it when I replaced things on my FP;

 

https://www.amazon.com/Dorman-902-438-Housing-Repair-Select/dp/B07KG7K8GB/ref=cm_cr_arp_d_product_top?ie=UTF8

16 hours ago, dburton97128 said:

Not a spark plug problem, sparks plugs don't fail all at once like this.  Could have been total absence of spark, maybe coil or something, but I would have thought I would get a code for that.  Check engine light on but that is expected when the engine is not running.  Goes out a few seconds after starting.   It was not particularly cold.  ~125,000 mi.

I'll look into the fuel pump cap issue.  Does sound like that could be it.  I'd like to identify exactly what parts my car might need before opening it up.  Hopefully can figure that out from that thread.  BTW this is actually a 2003, not 2004.

Thanks.

You'll need a used fuel cap and new oring.  

New aren't widely available though they were for a short time you could get a "filter kit" for other models that came with a cap that would work, but they're not widely available any more. 

I have a good cap and new viton oring i can send you for $20 or so, or you could post in the parts wanted section someone else probably has some. 

I think this oring works:
https://www.amazon.com/928-Viton-Ring-Durometer-Round/dp/B0051Y1TUK/ref=cm_cr_arp_d_product_top?ie=UTF8

I had a fuel regulator fail on my h6 and it did that.  It was intermittent at first with rough running and then had a whole bunch of cylinder misfires on one side of the block.  Replaced the regulator on that side and it ran like a dream.  Years before, crank but start was a bad crank sensor.  Just went out one day.  no prior codes.  

 

3 hours ago, 3Pin said:

I had a fuel regulator fail on my h6 and it did that.  It was intermittent at first with rough running and then had a whole bunch of cylinder misfires on one side of the block.  Replaced the regulator on that side and it ran like a dream.  Years before, crank but start was a bad crank sensor.  Just went out one day.  no prior codes.  

 

Those fail so rarely on Subaru's - how did you diagnose it? 

I always wonder how I'll track that down if I run across one. 

3 hours ago, 3Pin said:

I had a fuel regulator fail on my h6 and it did that.  It was intermittent at first with rough running and then had a whole bunch of cylinder misfires on one side of the block.  Replaced the regulator on that side and it ran like a dream.  Years before, crank but start was a bad crank sensor.  Just went out one day.  no prior codes.  

 

 

was there fuel smell or leaking under the hood?

5 minutes ago, idosubaru said:

Those fail so rarely on Subaru's - how did you diagnose it? 

I always wonder how I'll track that down if I run across one. 

I've seen several times, all on mid-'90s EJs. Pull the vacuum hose and there will be fuel in it.

i read like a demon on the internet after doing a bunch of other basic diagnosis. On rock auto it was inexpensve(somewhat) part to replace.  The dealer wanted hundreds for it.

 

28 minutes ago, Numbchux said:

I've seen several times, all on mid-'90s EJs. Pull the vacuum hose and there will be fuel in it.

Thanks.  That might be similar on EA/ER engines too?

1 hour ago, idosubaru said:

Thanks.  That might be similar on EA/ER engines too?

Oh yea, same idea on basically any vehicle with a return-style fuel system. Returnless cars just have a spring, no vacuum/boost reference (as the regulator is located in the tank, not practical to run a vacuum hose back there).