So my FD still has the OEM charcoal canister by the fuel tank, and it looks like all the tank end plumbing is still attached and functional. But somewhere along the way when the PO went single turbo, the connection from the hard pipe pictured was left open. Question is what do I plumb this to? Or can it just be left open, assuming it doesn't create a fuel stink problem?

 

leave it open so it can vent. mine is just open to the world. if you want, put a hose on it and route it back under the car

 

I'd have more concerns about that, presumably, dash 6 braided supply hose, hose clamped under the al fitting to an equivalent of a dash 5 hardline. If the ecu is capable, re-installation of a purge solenoid and catch tank and a bit of hose is no great hardship I would think.

 

Concerned over fuel flow with the different fuel supply/return line sizes? Given that this will be a sub-400HP build, I'm not too concerned about going from the roughly -5 OEM hard lines to the -6 fuel supply & return lines in the engine bay. I've got the same fuel plumbing setup in my FC, and it dynos at ~ 380RWHP and has zero fuel flow or fuel pressure issues. Suspect the same will be the case for my FD when it's done - then I'll test & log lots of data, and then determine if that's something that needs to be fixed.

I'm in the middle of doing a full harness rewire of the Link G4+ ECU as we speak, and I think I have a spare output that I can use for a purge solenoid. FWIW, I wonder if that's really necessary or not though. Reviewing my FC's FSM, the 13BT didn't bother with a purge solenoid; Mazda just "T"ed that evap line in with the PCV system. The PCV controls the flow, and acts as a check valve. I currently don't have a PCV valve on my FD, so if I did something similar, I believe I'd need to add a mechanical check valve (or a solenoid valve that is programmed to only open under vacuum) to the evap line so when the motor is under boost, you're not pressurizing the evap line.

 

Stock, that line goes to the rat's nest, then to a small black plastic canister that sits under the opening of the throttle body. From there it goes an aluminum one way check valve that has a ball and spring inside, then to the purge solenoid, then to the upper intake manifold.

It's been a LONG time since I looked at this setup on the FC so I can't remember the details. Tying it in with the catch can setup may be a good option, or routing that line to the turbo inlet, that way any vapors are consumed by the engine. Not sure if that would be enough to make the car run odd or anything. Also, I'm not sure of the logic of how the purge valve works stock, I think it only opens at certain times to pull in vapors to be burnt.

Dale

 

My FD currently lacks a PCV valve, as the PO put one of those Mazdaspeed low profile oil filler caps with a -10AN fitting on it, which he just plumbed to a vent hose. While that works, it would never pass a safety inspection for a track day, so I'll be adding a baffled/vented catch can to plumb that -10 blow-by hose into. I suppose I could plumb the evap line into the catch can too, but that probably won't do anything to prevent fuel vapor stink, as it's still an open vent.

The FC 13BT setup is pretty simple, and it combines the PCV and evap emissions functions. On the FC, that open evap line (which connects to the canister that stores fuel vapors when the car isn't running) gets "T"ed to the PCV blow by line. When the engine is above idle speed, but still pulling a vacuum, a ported opening in the TB applies vacuum to the PCV valve, which allows crankcase blowby and any fuel vapors from the canister to get sucked into the engine and burned. When under boost, the PCV closes, and then any blowby gasses & fuel vapors take a 2nd route to the TID through a check valve.

 

Thanks for the FC refresher! I used to know that stuff cold .

The FD has an actual PCV valve stock, it's a grey/black plastic valve. There are 2 nipples on the oil fill neck stock, one points towards the passenger side and one points down. The passenger side pointing nipple goes to the PCV then goes to the UIM, there's a large (6mm) nipple pointing forward on the UIM. The one that points down goes to the metal rat's nest and eventually to the primary turbo inlet.

In '95 Mazda got rid of the PCV valve and capped the UIM and oil fill neck off and just ran with the one line to the turbo inlet.

The FD does have a charcoal canister, it's back by the fuel tank. The FC had it in the engine bay, back passenger side near the cruise control.

Dale

 

Not worried about the flow, just the potential of the supply line blowing off as the rising rate of the fpr kicks in and the rubber hardens with age. ID of the dash 6 is larger than the line you're trying to plumb. Normal rubber hose is a tight fit and expands to accommodate the hardline, this is just flop on, and you're relying on the hose clamp to try crush the outer braid and then the rubber inner down to size. Have used those fittings in the past, I know the earls variety at least likes to strip the worm on the clamp and refuse to use them for anything pressurized.

Depending on how much boost you are going to use and at 400hp it wouldn't appear to be a huge amount, these style of fittings, that seem to be made by every company, will handle that no problems https://www.redlineauto.com.au/p-287...tor-516in.aspx the olives can handle the small difference between 5/16" and 8mm, in my experience you have to cut the olive off the tube, if the fitting is installed correctly. There's also a female/female variety.

Probably just a reflection of improved electronic controls and changed emission standards. The only downside I find, assuming you have the outputs, is the way the catch tank attaches to the underside of the TB and elbow, need double jointed wrists and 1/4" uni drives to access and you can count on dropping the 10mm nuts at least once or twice - at least on a rhd. I haven't encountered any alloy one ways between the tank and the solenoid on FDs here that Dale mentions, there's the usual plastic one, post solenoid, leading to the UIM.

 

Has anybody had issues leaving the line that runs to the engine bay from the charcoal canister open?

On one FD I have it connected to the hard line that runs to the engine bay, and it just vents to the atmosphere. I don't smell any fumes ever.

On the more recent FD I bought, the PO removed the steel lines and ran new AN fuel lines, with no evap line. He also cut some of the evap hoses by the fuel tank, so I get heavy fumes during cornering. I just ordered the evap components and hoses that mount by the fuel tank, so I can put it back to stock minus running an evap line back to the engine bay from the charcoal canister. Anyone run into issues leaving it like this?

 

I've had mine on open on both of my FDs for quite a few years with no adverse affects. Like I mentioned earlier in the thread, put a hose on it and route somewhere else if you're concerned about the potential smell

 

You have yours vent at the charcoal cannister and no smells?

 

one car has no charcoal canister and the other has the hard line vented in the engine bay. no fuel smell in either

 

On my FC with -AN SS hose I had removed the -6AN 5/16" hose SS braid and used fuel injection hose clamps (like mini T-bolt clamps).

After a couple non fuel fires (coolant and oil) I started to get leery of how poor of a fuel line solution the above was.

5/16" is not 8mm like stock hardline for one.
Second, the -AN hose wasnt meant to be clamped without its sheath and didnt clamp tight with its sheath.

I switched to Swagelock stainless 8mm tube compression fitting to 3/8NPT female fitting and aluminum male 3/8NPT fitting to -6AN male fitting.

Better silution than the 5/16" tube to -6AN deformable ferrule compression fittings people try to run on stock 8mm fuel hard line.