Overrun fuel cutoff - not happening!

ciphermonk
Posts: 23
Joined: Fri Nov 04, 2016 8:47 pm

Re: Overrun fuel cutoff - not happening!

Post by ciphermonk »

Great news! Glad that you got to the bottom of the issue.
stevieturbo
Posts: 1321
Joined: Sun Dec 07, 2008 2:04 pm

Re: Overrun fuel cutoff - not happening!

Post by stevieturbo »

Were you trying to use that setup via a purge solenoid, or was it just a total mistake ?
dr_jones
Posts: 162
Joined: Wed Jun 08, 2016 3:24 pm

Re: Overrun fuel cutoff - not happening!

Post by dr_jones »

A great relief to have soled it!

TBH it was just a total mistake - the car doesn't have the carbon canister / purge solenoid fitted (anymore) - somewhere during a rushed few days to get the car back up and running it ended getting plumbed back to the intake - but initially a one way valve on that line was installed back to front so only let air back into the tank - and of course that prevented any issue being caused - then months and month back I spotted that and reversed the valve without really thinking and didn't put two and two together.

No I'm in really in two minds as to which way round the non return should be - right now the line is VTA (which is fine) but the vent can only flow one way (out) - I guess technically this is wrong(?) as in theory there could be vacuum situation - though I can't say I've ever noticed a problem. However if I install the other way around (where air can be drawn back into the tank) the there is no 'pressure relief' - I'm not sure really which is the worst situation!
stevieturbo
Posts: 1321
Joined: Sun Dec 07, 2008 2:04 pm

Re: Overrun fuel cutoff - not happening!

Post by stevieturbo »

dr_jones wrote:A great relief to have soled it!

TBH it was just a total mistake - the car doesn't have the carbon canister / purge solenoid fitted (anymore) - somewhere during a rushed few days to get the car back up and running it ended getting plumbed back to the intake - but initially a one way valve on that line was installed back to front so only let air back into the tank - and of course that prevented any issue being caused - then months and month back I spotted that and reversed the valve without really thinking and didn't put two and two together.

No I'm in really in two minds as to which way round the non return should be - right now the line is VTA (which is fine) but the vent can only flow one way (out) - I guess technically this is wrong(?) as in theory there could be vacuum situation - though I can't say I've ever noticed a problem. However if I install the other way around (where air can be drawn back into the tank) the there is no 'pressure relief' - I'm not sure really which is the worst situation!
IMO the tank should be able to breathe either way in and out.

There needs to be a rollover valve for protection against spills if the car gets a bit silly. Not a check valve. And if you want to appease the hippies, the vent should not be to atmosphere...but of course it is much simpler that way.

For the hippies a purge solenoid to the intake is one option, I guess another would be to route any vent towards the air intake via a charcoal can if you want and back into the air filter area or pipework for natural breathing.

I prefer the simple option.
dr_jones
Posts: 162
Joined: Wed Jun 08, 2016 3:24 pm

Re: Overrun fuel cutoff - not happening!

Post by dr_jones »

Thanks - that makes sense of course.

I'm also for the simple option - especially with the subaru - all too easy to end up with an engine bay looking like the spare hose / harness bin....
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