Anyone's Z take a deeep intake of breath when taking the fuel cap off to fill up?!!....Mine does, and I've been meaning to ask if this was normal for a while now?!!

 

Is there a breather pipe on the tank that might be blocked? It looks like I have an original cap, which seems to have breathe holes on it?? ( on the end of the threaded nozzle end which screws into the fuel filler pipe). I'm not sure if thats perhaps how it's supposed to breathe and that there's no breathe pipe?

 

I could change the cap for one of my many get you home types in the garage, but wondered if the sucking in was normal?!! I'm going to nip out now after considering this and see if it does it cold (will edit tomorrow accordingly!)

this might help :) http://www.300zx.co.uk/cgi-bin/manual.cgi?list=fe&dir=&config=&refresh=&direction=forward&scale=0&cycle=off&slide=3&design=default&total=4

do you mean it sounds like when you open a can of fizzy pop, as thats normal its just pressure escaping most cars will do it, unless theres a leak in the systym or IIRC carbon cannister is removed. Then its just fine ;)

Just been out and no 'intake' after lying idle for 4 hours. I've whipped the cap off and there is a tiny valve which is a bit iffy and does'nt open properly to let air in when i suck on it! (I asked the GF but she told me where to go!!!)

 

Just taken the plastic end off and there is a valve but it's only one way, (Into tank). Good for trapping fume evaporation, but seems strange to have if the car should get warm in hot weather and the air inside teh tank expands?? Anyway, i'm soaking it in some warm soapy water for a few mins now and i'll warm it in a pan of oil before i dry it off and put it back tomorrow.....I think its just the rubber on the valve needs lubing up...Again i went to ask the GF but she's gone to bed!!...Just wondering if teh valve is US or is supposed to be one way??

 

Cheers for teh link Vijay..will have a quick read now..

I get it after a short run 7-10miles and open the cap as fuel is being pumped and creating a vacuum as the tanks not breathing....Looking at the diag Vijay posted, the breather (ventilation hose) feeds off the filler neck, but from behind the cap - So in theory it can't breathe if the cap valve does'nt open!

 

think it's my cap..

 

Greg whats the 'IIRC carbon cannister'??

http://s95014253.onlinehome.us/63104/6901.html

The 'sucking' is normal AFAIK as it's a pressurised system.

Thanks for this Guys..

 

It's my cap i think, and I defineatly feel that its valve is a bit dodgy, as i get no air flow when i suck on it. If i suck really hard i get a bit through, but I have to push the valve nipple to get any significant air through it! (I took the the black turning handle off the top to reveal the valve).

 

I was just concerned that the vacuum might be attempting to pull fuel back to tank when switched off,creating undue pressure on the pump rather than breathing in Air to to the tank to fill the vacuum void, or that this was effecting the pump operation on a longer run with a low/ 1/4 filled tank, which is allowing more of a significant vacuum pressure when there is more air space than fuel in the tank!

 

Looking at the manual diagram any vacuum should be filled through the one way valve in the cap.... could be design issue as the Fuel Pump and flow use is probably significantly more than the valve size in the fuel cap, or as i suspect, it's just a sticky fuel cap valve....

 

It was this i was looking for comparisons on really....nothing major, just another niggle that i've been meaning to ask about!

 

Thanks again for your comments

 

Damian.

The carbon cannister system purges fuel vapours from the fuel tank, threrefore if its working correctly you will have a vacuum in the tank when you remove the filler cap ;) The one way valve in the cap will have a certain release pressure which maintains a certain amount of vacuum. Sounds normal to me....