Overfuelling

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Nutter Kam

Overfuelling

Post by Nutter Kam »

Narrowed down my dead car to overfuelling problem. Car starts but will die after initial combustion. If I keep my blipping the throttle car will stay running for longer. ECU not giving any codes - replaced the ecu just in case it was spiked anyway. Throttle sensor is giving correct readings. Fuel pump is working but could this be pumping too much?? Manual says it could be MAF (tried couple of spares but no different), air bypass valve (but have no idea where this is or what it looks like), fuel regulator (can't find this either!), water temp sensor and some other stuff. Definitely overfuelling cos removed plugs a couple of times during my investigation and all are fouled black (I've put some new plugs in the process). Can anyone provide any tips, general help? Obviously, can't drive car to anywhere for diagnosis.... sigh
Josh Colombo

Overfuelling

Post by Josh Colombo »

The Air bypass valve is pretty much right below the PCV valve. It's very possible it could be this. Fuel regulator is on the back of the passenger side fuel rail. It has a vacuum line going to it. It looks like a little diaphragm thing.

Both the air bypass valve & regulator have the potential to cause problems.......but not sure if they would cause something that bad......

Josh
FREDERICK.WHITMORE@CN.CA

Overfuelling

Post by FREDERICK.WHITMORE@CN.CA »

Maybe it could it be your Oxygen sensor. This regulates the air/fuel mixture
right?

Frederick
Josh Colombo

Overfuelling

Post by Josh Colombo »

O2 sensor doesn't really do much when the car is in open loop. I can unplug mine and not even get a check engine light when it's sitting there idling.
Nutter Kam

Overfuelling

Post by Nutter Kam »

Josh, you really know these cars inside out!! Massively impressive.
Josh Colombo

Overfuelling

Post by Josh Colombo »

Thanks,

I probably know them too well....means I need some other sort of life....hahaha

I still learn new things about them, and some of the weird stuff subaru does.

Josh
Nutter Kam

Overfuelling

Post by Nutter Kam »

Ok - so it wasn't overfuelling! Mech tells me it's head gasket - pressurized water system. If I want to do the job myself how much of a nightmare is it? Most guys say it's engine out time. Probably a good time to replace the cambelt as well? sigh....
Douglas Hancock

Overfuelling

Post by Douglas Hancock »

Engine out. Timing belt would have to be easy. All you have to do is remove the radiator and you can get to it. If it does'nt need replacing in the next 10,000ks I would'nt bother with this. If you can pull a head off an engine, you can do the timing belt yourself. One thing I am not sure of though should you replace both head gaskets. It would be a nightmare to have the other side blow 5000ks down the track.
Nutter Kam

Overfuelling

Post by Nutter Kam »

Well, if the engine's comin out then I'd do both sides. heard of any cases with cracked heads? And what are likely causes head gasket failure and chances of repeat failures after fixing?
Douglas Hancock

Overfuelling

Post by Douglas Hancock »

No. Just check that the heads are not warped. Get a straight edge and check the face of the heads from side to side both ways and diagonally. If you can't see where the head gasket has been craked or really come apart then chances are that you have a craked head. By this time it time to see the ks on the dash and deside weather it is worth getting the heads rebuilt or picking up and secondhand motor or even reco the original. If you have 200,000 on the clock then yes I would do the heads and don't worrie about the bottom end but if you have 300,000ks it would make a great boat anchor.

If you have not had the temp through the roof then chances are the heads will be fine. I you rebuild the heads and put them back on your motor you may find it will use a lttle oil afterwards. Its your decision in the long run, but with new seals in the heads the oil will get through the rings and start to burn. Like I said 200,000 you should be fine, 300,000 it looks like its a boat anchor.

Get other opinions before you go and get the parts you need. I would just replace the gasket and put the heads back on. Don't even clean the tops of the pistons, But check for slap.
Nutter Kam

Overfuelling

Post by Nutter Kam »

thanks Doug
Bill Covert

Overfuelling

Post by Bill Covert »

You dont have to take the engine out to do head gaskets.I have done it. It is a tight squeeze but it is easier than pulling the engine.Remove all the junk on the fenderwells and you will have just enough room. Good luck,BillC
Douglas Hancock

Overfuelling

Post by Douglas Hancock »

I would pull the engine. You could do it in one day if theres nothing wrong elswere. 4bolts on the gearbox. 2 bolts on the engine mounts. Unplug every thing and the harness swings to one side. unbolt the exhaust from the engine and leave it hanging, use anti seeze when putting the nuts back on. 1 bolt for the starter motor. remove air filter. Lift engine out and sit it on the bench and get a seat and start pulling the head off.

You should try pulling a 2lt turbo out. It took 4 hours and it was out. New clutch and back in she went. Trouble I had was I found the flywheel was damaged there goes sat afternoon, sun monday and started getting back together tues, drive out wend. All work was done at night.
Nutter Kam

Overfuelling

Post by Nutter Kam »

impressive - I've looked at my schedule for the next few months and I've decided to stop deluding myself that I could do all of the above in between keeping family happy and work. Just gonna shell out loadsa spondoolies and pay a fellow Subaru nutter to do it! Would love to do the job myself but can't win em all eh?!
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