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J15 Tank Pressure

nickm - 23/12/13 at 03:40 PM

Hi
I have gone for the cheap trick with the tank pressure and just run a fuel line to a point below the bottem of the tank from the filler neck i have mulled it over in my head within the garage and i cannot see that any configuration of upsidedownness is going to result in fuel spillage as the outlet is lower than the tank and on the opposite side ??? the only fly in the ointment is can i get the IVA man to understand Archimedes principle and it does look a bit Heath-Robinson !

Any comments on my method ?

Sorry to hear about your ding Paul just when you thought it was finished !

Nick M

MikeRJ - 23/12/13 at 04:07 PM

How about if the car is on it's side?

theprisioner - 23/12/13 at 04:28 PM

I am not decrying what you have done. I assume you have the standard JP tank and location? but what happens when the tank is full and you park on a slope?

http://sylvabuild.blogspot.co.uk/2013/12/fuel-system-modifications.html

Jenko - 23/12/13 at 08:11 PM

Exactly what I have done...but to avoid issues mentioned by Mr Prisoner, the upward loop needs to be as high as possible. If the car is on it's side I guess in theory, you should still be able to climb out...failing that, you will end your days in a blaze of super unleaded glory.....what a way to go :-)

matt_gsxr - 23/12/13 at 11:14 PM

Why not fit a valve that is designed for the job?
http://www.thinkauto.com/onewayvalves.htm

These allow vapour out but not liquid.
I guess a pig-tail is more low cost.

theprisioner - 23/12/13 at 11:43 PM

A mocal valve lets fuel or vapour out . The point I was trying to make is if you fill the tank, park on a slope, run the engine the tank will pressurise then neat fuel will exit the pipe or valve regardless. Try it, I have!

Madinventions - 23/12/13 at 11:44 PM

I reused the rollover valve from my Fiesta donor (about as Locost as it gets!)

http://www.locostbuilders.co.uk/viewthread.php?tid=152148

Failing that, you could get one of these?

http://stores.ebay.co.uk/Torques-U-K/Rollover-Valves-Fuel-Tank-/_i.html?_fsub=1996911012

Ed.

nickm - 24/12/13 at 12:01 PM

On its side its fine as is upside down because the fuel top will be at 90 degrees to the car so leaning on the near side it cant reach the fuel tank neck on the drivers side the pipe is higher than the tank, parking on a slope ???? i can see another 90 degree bend being added !
Having fun at the moment with the ECU, me and computers dont get along. I can get it to idle but not rev but some of my issues are i need a nice day so i can run it outside in the fresh air without gassing myself or blowing the laptop up.

Nick M

matt_gsxr - 24/12/13 at 12:53 PM

quote:
Originally posted by theprisioner
A mocal valve lets fuel or vapour out . The point I was trying to make is if you fill the tank, park on a slope, run the engine the tank will pressurise then neat fuel will exit the pipe or valve regardless. Try it, I have!

The ones that I linked to
"A range of fuel tank valves that allows 1)air in to replace fuel used, 2) air out due to heat expansion. 3) a positive shut off to prevent fuel escape, due to splashing or even roll over. This is achieved by a two ball system, one hollow plastic, one solid steel"

I think the plastic ball floats in the fuel so blocks the flow, but I haven't done the empirical test.

Matt

Paul AS - 24/12/13 at 02:22 PM

Hi Nick,

glad to hear you're still cracking on with the car. I'm pretty much back together now - just the front clamshell to fit.

My tank has an 8mm vent outlet on the top with a fuel hose going straight up and looping back down and venting to the road. In the fuel line vent I have a CBS In Line Fuel Tank Breather Valve #FTBV2.

The IVA man was happy, it works with the car the right way up, and I hope to never find out if it works with the car upside down!!

What sort of stage have you got to Nick?

theprisioner - 24/12/13 at 02:26 PM

My understanding is there are at least 3 types of valve that I can find reference to:-

1) One way tank valve ( as it implies but can cause tank pressurisation)
2) Mocal valve (0.5bar in and 0.75 bar out) This valve will bypass if the tank pressurises. In some cars the fuel is collected in a carbon filter.
3) Roll over Valve (this will shut off if inclined >90deg) This product will still bypass if you park the car on a 15deg slope and the tank pressurises.

The best compromise IMO would be a Roll over valve with a U shaped pipe with enough head. 1>I did not allow for this valve in the design and 2> I have insufficient head to put in a U shaped pipe (J15).

I had the above mentioned system in my last Westfield and only very occasionally on a very full tank it would still dump fuel on a slope.

Do I have all the answers, definitely Not, if you find another valve, (preferably with link) please let me know.

nickm - 26/12/13 at 08:23 PM

Hi Paul
The car is virtually there really dash and h/brake not started yet.
The boot and bonnet are ready for fitting and fettling just need some good weather really before fitting so i can get the space to check the alignment and symmetry and leave the last mm to the fasteners.
Little jobs really like fitting the seats and harnesses which i dont want to do till the h/brake is complete and mirrors which i dont want to do till after the seats if you know what i mean.
You must have been pushing hard to damage it after the grip i experienced at Blyton ! i left that day wondering why i spent all that money on the engine upgrades, i hope whenever i go for IVA the date is dry as its a 180 mile round trip across the Lincs Wolds if its wet i can see me treading quite carefully !!!! mind you i want to run the engine in carefully until i take it to Emerald for a session, but seeing as all i can get it to do at the moment is idle !!
On the road for the summer ???

Nick M

theprisioner - 26/12/13 at 09:14 PM

It will be great to see another J15 on the road.