Well, I just ordered a fuel pump assembly, but good to know if that doesn't work.

I very much hope it is the fuel pump. Replacing valve springs requires engine taken out. Good luck.

It's not valve springs. Poor idle and sudden improvement under load? No way.

On today's episode of Spud's Subaru Saga, Spuds learns about in-tank rollover valves...

I need to get a thinner (and probably longer) hose...

Hose for siphoning? Tell me about the rollover valve. I don't see it in any diagram.

Apparently modern fuel tanks have a check valve where the filler neck and vent meets the tank to prevent the gasoline from spilling out in a rollover. No it's not on any of the parts diagrams, so I am assuming it is integrated into the fuel tank itself. If you look up "how to siphon fuel from a modern car" you will see that a lot of people encounter this problem and the solution is usually to use a 1/4" OD tube. I had a 3/8" tube and while I did seem to make it fit through the valve it had too much resistance to get it further into the tank.

Edit:. To answer the first question, yes, I need a thinner and longer tube for siphoning. Not sure why I said hose lol.

I've struggled with that flappy valve in the past. How far can you get your hose? Does it maybe hang up on the sharp bend nearest the tank?


https://parts.subaru.com/images/part...0_42001387.png

It's hard to tell, there are a few bends I can feel it getting through on the way down, but hard to judge which is which when you can't even see the tube. I think a thinner hose might help a bit there as well.

Transfer pump? HF has a good one for 10$

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Where would you connect the transfer pump to get at the fuel?

Long skinny tube? IDK.. I was tired when I posted this [emoji1787]

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Alright, got the tank draining now, more on that later.

Any of you all know if there is a typical way to remove subaru seats without removing the rails?

Well, the good news is that I successfully replaced the fuel pump assembly without lighting anything on fire. The bad news is that it was ineffective in solving the problem...

Only other thing in the tank I can think of is the sending unit on the other side of the tank, which has its own fuel inlet and filter, feeding the pump through a line crossing above the tank. Maybe that is clogged or the line is messed up somehow?

I guess injectors next?


PS. Anyone need a perfectly functional OEM Subaru Tribeca fuel pump assembly?

Are you absolutely 100% sure that those plugs at 5 and 6 are firing? Can you get at the power for the igniters to unplug them while the engine's running? If it runs worse, or dies, then that cylinder was firing.

You can also remove the igniter and test it using a new plug and a ground strap. Testing is key. Think of how much time and effort went to replacing all that perfectly good shit.

I've dealt with simultaneous seemingly-independent failures. It's rare but it happens. I've also dealt with a couple engines that were consistently wrong in how they reported misfires.

Well, I swapped both the plug and ignition coils forward a cylinder, so 6-->4, 4-->2, and 2-->6 and it is still showing misfires on 5 and 6. Plugs looked fine themselves. I only did the left bank though, I could try the right bank but there is more shit to remove to get to the plugs. The only plugs for the coils are right on top of them, and being a boxer, I don't really want to stick my head between the engine and frame rails. Plus, I need to remove the battery to get to one side, the air intake to get to the other.

Yeah, there is a possibility that it is reporting misfires incorrectly. It definitely feels like a misfire, but it could be reporting which cylinders are misfiring incorrectly.

What would cause misfire through the first third of engine speed? Vacuum leak? Dirty MAF sensor?

Both of those seem possible... Wouldn't I also see pretty high fuel trims though?

I think so. You would've seen the same with low fuel pressure. I would focus on the spark by removing one igniter at a time and testing visually with a spare plug.

Today I learned that fuel system cleaner has a purpose and is effective at that purpose. Oh wait, wrong thread. :bonk:

Anyway, put some high strength Techron in the tank, started it, and misfire was gone before I finished pumping up the tires. Still has an occasional miss, but it's so much better now that I am 99% sure it was something in the fuel lines or injectors. If the occasional miss sticks around I know where to look.

Now I need to deal with the whole 2 months without moving set of problems like that new clunk sound coming from the back...

Ok... Update for anyone who cares:

Misfire is still occuring, but MUCH less often, and it's now up in the 2-2.5krpm region only under increasing load conditions (any time you begin to accelerate). Interesting point is now it only throws a code on cylinder 5, which is an improvement from both 5 and 6. I also am pretty sure I heard a detonation one time at high load going up a hill. This all seems to be evidence of an injector/clogging issue, though it's more of a PITA to get at the injectors than the spark plugs believe it or not. Friggin sound deadening plates...

Anyway, I'm going to run another tankful of new gas with injector cleaner through it and see if that resolves the issue. If that doesn't work, maybe get an injector tester? If it is working electronically, Idk how to deal with a clogged injector yet. Might be a replace kind of deal?

I'm no expert but I've opened up some nasty rails. Consider gravity and that the failing ones are at the rear. If it was mine, I'd crack it all open to inspect. I might have wasted my time but I'd feel better knowing. Maybe a couple junkyard injectors... taken from the front? ;)


I get that it's a PITA :(

So you think the rail itself might have gunk in it (too)? Didn't think about that... I suppose it's not much more work than it is to just get at the injector itself. If it's got gunk, clean out the rails and get new injector for the rear? If the rails are clean, I suppose I still need to get a new injector...

Maybe not the rails but the shit would definitely tend to settle at the low point. No idea how much there is. Maybe just more injector cleaner but I've never trusted it. Maybe it just broke loose more shit from upstream.

Not entirely rational but, if I already kind of had to go that direction, I'd check it.

Pulled fuel injectors to test them. Broke an o ring. This might sound like a stupid question, but what is the best way to order the right orings to replace them with? My Google fu is weak today. Denso 711DC is printed on them.

Edit: Nevermind. I'm a dumbass. You CAN look that up as a vehicle-specific part, but at multiple dollars an o ring that seems like a ripoff.

This place seems to think a generic size for these is 7.8x1.9mm which seems about right...
https://theinjectorshop.com/products...-bulk-pack-100

Probably ok but, as long as you have them out, just take one to an auto parts store.

"What?" you say. "Brick and mortar? Ok, boomer."

Well, that should have been the obvious solution... Yeah I'll bring it next time I go. The problem with that is the local store doesn't usually stock useful stuff like that. Really missing that big regional NAPA near where I used to work.

I was actually just at the auto parts store earlier today to pick up stuff.

Regional NAPA warehouse is right across the river from me in Portland. There are closer places but it's often worth the trip. I got to know a couple of the guys there on a first name basis a few years ago. The shit-talking was fun.

Well, I found A problem... Not sure if it is THE problem. One of the fuel rail pulsation dampers is missing the adjustment screw.

In other news, all the injectors seem to be working fine under low pressure at least. Ran some carburetor cleaner through them while pulsing and noticed no difference between them. Microfilters on the inside looked intact and clear too. Might swap them around when I put it back together just in case I still have the problems. At least then I'll isolate it to a specific injector or something else on cylinder 5.

Edit:. Debating whether to get a right side fuel rail for ~$80 (in addition to damper for ~80) because of all the rust. I got it cleaned up a bit but needing a chisel to remove some of the rust isn't confidence inspiring when looking at a pressurized fuel tube that goes next to the engine...

Interesting! I was not aware of the dampers with those limit screws. Some googling confirms correlation with your symptoms. I think you may have found it. *knocks on wooden coffee table*


for instance... https://legacygt.com/forums/showthre...1924.html?amp;

Lol I did find that in my research into 'wtf are these things called'. Hopefully I can have this finished by next weekend. Need to bring the other automatic car in for some warranty work and there will be hell to pay if we don't have a working car my wife can drive...

I've known that those dampers exist but I've never seen what can happen when they go. Opens up a whole new world for me. Once I read "standing wave" I slapped my forehead, "duh!"

:sigh:

Nope, that's wasn't it... Still have a cylinder 5 misfire, same symptoms...

Now the question is whether to investigate spark more thoroughly or go after compression. I think the latter might be a take it to someone to fix it kind of thing. Or write it off as dead to me.

:mad0259:

If you can get to the plugs easily (I am unfamiliar with your vehicle) a compression test is both easy and conclusive... but I would not associate compression issues with your symptoms.

Yeah... It's a Subaru H6. Plugs are not easy to get to. They are, ironically, easier than injectors to get to considering the injectors are on top...

But that is certainly something I can try! :thanks:

Can you guess which one came off the "top" of cylinder#5? Hint, look at the resin.

Is it the one on the right? I wonder if that red dot is thermal paint. An indicator of overheating? WAG


I'm telling ya, Igniters don't last forever. And they can get really sketch for a long time before hard failure. Weak sparks are bizarre animals.

The left one came out of cylinder 5. If you look closely, the resin is cracked.

That being said... Hmmm thermal paint huh. That would be pretty clever

I am discovering that. The weird thing is that the behavior changed so drastically right after I added the fuel line cleaner... :iono:

Oh well, here goes something crazy...

Oh, duh! I see it now that I enlarge the pic. NVM my stupid paint idea. Prolly just random pen color for specific QC inspection.

Unless those are a magical stout design, in my experience they're like light bulbs. I've tried to be thrifty on a couple different vehicles and ended up chasing failed ones both times.

$80 light bulbs...