And here I just did a one person test so there is no one way valve it is just a bypass valve, fumes come out of the tank and air comes in, and it makes senseYep thats it, I know if I blow the vent hose and goes into the tank, all I need to know is if air comes out oe the ven line blowing thru the filling tube, Thanks
Will do that,You need to do some research. Several threads on here and the Corral with this very thing discussed.
For example, see post #4 and Michael is well respected in the Mustang community:
Gas tank has pressure in it. Whats stopping it from venting?
Whenever i open the gas cap pressure is relieved. I don't think that the tank has come down before so don't know if the vent line has been pinched or not. I thought maybe the casiter solenoid wasn't working, but then I remembered that cansiter doesn't hold pressure, only fumes, which are purged...stangnet.com
I was just reading an article related to this concept and now I'm not sure what is a fact.
"I did a little research and found that the tank breathing valve allows first the relieve (Exhale) vapors caused by motion and heat but also it is a breathing valve (Inhale) air as the fuel tank gets empty to avoid implotion" So is it a one way or a bypass valve??? I'm confused
I don't know what to tell you.
You have pretty much joined a conga line that is headed for the twilight zone.
Yeah I’ve been thinking about injectors upgrade to at least 24lbs, and no doubt tuning would narrow me to the best and optimum performance.
Unfortunately I’m too late for a Moates Quarterhorse, unless I put my hands on a used good condition unit somehow.
Thanks for the ideas
Getting complicated. Here portions of a chilton’s book which many people think is garbage but I’m sharing it anywaysDo I took my own advice and did some searching as what nicholase posted got me thinking. I found this description on CJ Pony Parts for the "Fuel Tank Vapor Valve"
"This Ford E7DZ-9B593-A Fuel Tank Vapor Valve is designed to be a direct fit replacement for 1980-1998 Mustangs. The Fuel Tank Vapor Valve vents to the carbon canister. The Vapor Valve mounts in a rubber grommet on the fuel tank. A vapor space between the fuel level and the tank upper surface is combined with a small orifice and float shut-off valve in the vapor valve assembly to prevent liquid fuel from passing to the carbon canister. The vapor space also allows for thermal expansion of the fuel."
So this makes sense and in a roll over or an overfill situation the float should stop the fuel from going down the vapor line. So with that if the charcoal canister or the vapor line between the tank and the canister have fuel in them then I would still say the valve is not working properly.
This is from a post by Saleen0679 on a Corral thread:
From the manual:
Pressure/Vacuum Relief Fuel Cap
WARNING: FUEL TANK MAY BE PRESSURIZED. TO REMOVE, ROTATE OVER ONE-HALF TURN COUNTERCLOCKWISE. IF CAP IS VENTING FUEL OR A HISSING SOUND IS HEARD, WAIT UNTIL THE CONDITION STOPS BEFORE CONTINUING TO TURN THE CAP. IF THESE PRECAUTIONS ARE NOT FOLLOWED, FUEL MAY SPRAY AND CAUSE PERSONAL INJURY.
The fuel cap contains an integral pressure and vacuum relief valve. The vacuum valve acts to allow air into the fuel tank to replace the fuel as it is used. The vacuum relief valve opens after a vacuum of -3.4 kPa (-0.5 psi). The pressure valve acts as a backup pressure relief valve in the event the normal venting system is overcome by excessive generation of internal pressure or restriction of the normal venting system. The pressure relief is 11 kPa (1.6 psi). Fill cap damage or contamination that stops the pressure vacuum valve from working may result in deformation of the fuel tank. Care should always be taken to use a proper fill cap in good working order.
The fuel cap is a threaded screw-on design with a pre-vent feature that allows the tank to vent for the first three-quarter turn before unthreading. All fuel caps are attached to the vehicle with a tether using the filler pipe-to-housing screw at the three to four o'clock position. The fuel cap assembly provides pressure and vacuum relief functions and should be replaced with the proper pressure/vacuum relief cap to prevent possible system malfunction
I do not know what "manual" he is talking about but my guess is the owner's manual. I went to look for mine and cannot find it so I cannot verify that all of the above came from a 86-95 Mustang manual. I am going to be a little upset with myself if I have somehow or another lost my manual...
The more I read on this my assumption is that our gas caps are "non-venting" which by definition means they do not relieve vacuum or pressure. I removed the gas cap on my Coupe and its has a pretty substantial seal where the cap comes to rest on the filler neck. I grabbed a picture of the gas cap off of LMR, what is the purpose of the holed and whatever is in the end of the gas cap if this thing is non-venting? It looks like a way for the cap to relieve to me but I am not taking mine apart to confirm.
I went out and looked at the charcoal canister on the Coupe as I seemed to remember caps on top of it and confirmed they are there. Does anyone know how the canister functions air flow wise? I understand how charcoal absorbs hydrocarbons and that the line from the tank goes to the canister and then a line comes off of it to the solenoid that is then connected to the upper intake. What I want to know is how the air moves in the charcoal canister itself is what I want to know. Curious to know if the vents on top of the canister will allow air leave but not get sucked in or what.
I have gone far enough down this rabbit hole over lunch so hopefully someone else can add to this as there does not seem that anyone really knows how each piece in the system functions just that they are all part of the system and vapors go from the tank to the motor.
That makes some sense. Would a 190 mph pump create excessive cavitation?Somebody holler out if/when he drops the tank.
I'm also reminded of a video that was going around for a while, about cavitation in the tank from high volume fuel pumps.
I and others, have not encountered the issues laid out in the video but we all don't live in the same conditions so...
Might we worth taking a look at how "violent" your normal return fuel volume is. It sounds as if maybe a lot of excess vapor could be contributing to your issue.
The fix in the video was to extend the return line to reduce all the splashing from the return fuel.
Ah! I found it:
Thoughts On Fuel Pump Cavitation
View: https://www.youtube.com/watch?v=Ium8jf4Jm04 IMO this video seems to exaggerate what really happens. Since when does 100% of the fuel get returned back to the tank? Has anyone with a 255lph fuel pump experienced unusually high pressure at the fuel rail caused by cavitation?stangnet.com
Thank you, I'll look into thatDecipha at efidynotuning.com still has some for sale, along with chips and chip burners.
That makes some sense. Would a 190 mph pump create excessive cavitation?
Oh, okI can't answer that for you. I have an in-tank 255L High Pressure fuel pump and have not encountered this issue.
Yeah I agree with your assumptions I will look into all of those scenarios. Thank youCavitation will most likely only happen at idle being that is when most of the fuel is being returned. Problem some have reported is issues tuning at idle or just off idle with a low fuel level.
I cannot see this happening with a full to below half a tank of fuel just due to the amount of Kiel around the pump. If it is happening then the lower the fuel level gets in the tank I would think the easier it would be for this condition to happen. Again if it is happening then the lower the fuel level gets the longer the cavitation would affect fuel getting to the injectors which would affect the tune. Not sure this is something you could tune for as lack of fuel is just that.
All the above is predicated on if the condition is happening. I decided to change pickups when I reworked the fuel system on my car but it made sense to do it then as I changed just about everything from the tank to the injector rails.
You’re correct the incoming fuel vapors fitting is behind than fitting on the upper left side, but generally that’s the way it looks.
Isn’t an accurate picture / drawing of our charcoal canisters in that there is flow from the tank into the canister and then flow out of the canister to the intake. It’s missing the flow from the tank.
My guess is when there is flow from the tank and the solenoid valve is not open the fumes are pushed through the charcoal and out the vents. When there is flow through the solenoid valve the vapors from the tank are sucked into the upper intake. This also leads me to think that when the solenoid valve is open fresh air is also drawn through the vents and down through the charcoal to reactivate it and this air enters into the upper intake. This would be unmetered air but I don’t know how that would affect the ECU.
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