I have a 2003 Outback H6 that hesitates and backfires when under a load. Like going up hill or passing. I'm thinking fuel filter or plugs and wires. Then I realized the car doesn't have wires, it's got the solenoid packs at each plug. The check engine light never comes on either.

 

Anyone know what's going on?

 

Thanks,

How many miles? How old are the spark plugs?

The car has 157k on it. It's relatively new to me so I have know idea how many miles are on the plugs.

It could be the plugs... but I bet you pull 'em and they look brand new, if they are the factory brand.

If someone put in lesser plugs at 60K or even 120k, who knows.

 

Codes can be stored and ready to be read even if check-engine light not on at the moment.

 

I'd say also check fuel pressure, could be the O-ring problem.

Does the H6 use the same goofy pump assembly as the 4 banger?

That would be a possibility, but I would also expect hard starting if it were causing a misfire issue.

 

Spark plugs could be ancient. I would at least pull one out and check its condition. Even platinum/iridium plugs will have wear on them if they're 157k miles old. If they're not that old, make sure they're the correct recommended spark plug. Usually the plug type will be in the owners manual in the maintenance section.

Sounds like a fuel supply issue to me.Pump or filter.

Replace the filter first.Nothing lost if that is not it.

 

An on road fuel pressure test would be great.

yes, same fuel pump design, actually, I think the initial cap/o-ring complaints on fuel pumps all came from H6es.