Preassure sa Gas Cap

[Erick Chavez]

Just recently nagpalit ako ng fuel pump kasi me tagas na sya, tapos mga ilang araw napansin ko pag binubuksan ko yung gas cap meron malakas na preassure akong nadidinig, hindi ko lang ma identify kung pahigop ba or palabas yung preassure, yung gas cap mga sir is mukhang sealed at may rubber o-ring sya, wala ding butas, normal kaya yung pressure po na yun? thanks po...

=> KIA Pride GTX 2000 Model Manual

[dr. d]

Just recently nagpalit ako ng fuel pump kasi me tagas na sya, tapos mga ilang araw napansin ko pag binubuksan ko yung gas cap meron malakas na preassure akong nadidinig, hindi ko lang ma identify kung pahigop ba or palabas yung preassure, yung gas cap mga sir is mukhang sealed at may rubber o-ring sya, wala ding butas, normal kaya yung pressure po na yun? thanks po...

=> KIA Pride GTX 2000 Model Manual

when i read up on auto literature here, i get the impression the gas tank is "pressurized". maraming nagsasabi na pag bukas ng gas tank cover ay may maririnig na tunog ng hanging lumalabas o pumapasok.. now, i grew up knowing gas tanks have a breather tube, whereby pressure in the gas tank is equal to pressure outside it. so i am now also confused..
anoba talaga, mga koya?

[nivraarvin]

Same dapat ng pressure yan sa atmospheric pressure. Kung negative pressure mahihirapan kumuha ng fuel ang fuel pump. Kung positive pressure, could be fuel vapor.

[t2erns]

research nyo evaporative emission system. marami rin may fuel tank pressure sensor.

[Erick Chavez]

napansin ko kanina medyo malakas yun preassure and parang palabas sya

[alfonsomiguel]

sir erick, nung sa car namin, nag-aamoy gas sa may gas cap area. Pag binubuksan ko, wala singaw maririnig. Try ko sa iba car buksan ang gas cap, may "pressure" na lumalabas. Pinagswap ko mga gas caps (both cars are honda), lumipat yung amoy gas. So sa gas cap may problem. Incidentally may friend kami galing US, nag pabili ako ng honda gas cap (mahal kasi sa honda dito sa atin, 2k petot). Nung binigay sa akin yung cap, inusisa ko. May warning label sya na "Fuel spray is dangerous", "Open slowly". After mapalitan ang gas cap, pag binubuksan, may "pressure" na sya.

[[archie]]

Meron talaga pressure sa gas tank. Kung walang pressure, magaamoy gas yung oto kasi hindi sealed.

[SiRbossR]

Pressure o Vacuum? I've only experienced Vacuum when removing the filler cap.

[[archie]]

Vacuum sir

[jaypee10]

meron talaga i have 96 vti minsan kasi pag nililinis ko ung sa lagayan ng gas..binubuksan ko din at may pressure talaga hangin na palabas ..
natural nalang daw un sa mga may fuel pump na sasakyan...

[Erick Chavez]

research nyo evaporative emission system. marami rin may fuel tank pressure sensor.

thanks sir, after i trace ko yung mga hose mula doon sa fuel neck at sa ilalim ng car, may nakita akong damaged na hose from tube sa ilalim ng car malapit sa gas neck papunta sa compartment sa likod tapos doon sa loob ng compartment naka attach yung hose sa may black plastik box na may valve, eto siguro yun evaporative emmission system, after ko palitan yun na damage na hose hindi ko na halos na papansin yun sound ng preassure coming sa gas tank pag binubuksan yung gas cap..

problem naman e naging erratic yung idling nya, pag start mag stabilize sya ng mga 1000 rpm then after mga 5 secons bigla baba sa 500-700 pero hindi stable, taas baba sya at nag sha-shake yun engine :D

thanks po sa mga nagbigay ng inputs..... :cheers:

[jick.cejoco]

cars compliant to OBD II are designed to pressurize the system after shutdown and a pressure sensor monitors the pressure if it stays for a predetermined time from a slow calibrated leak. the objective is to check the the integrity of the hoses, tanks and the pressure cap if there are any leaks and to illuminate the malfunction indicator light if there are leaks. the vapors are stored in the charcoal canister to be used as fuel as the engine warms up and the throttle is above idle position. the pressure cap is a compound cap, there is a pressure cap that prevents release of fuel vapors into the atmosphere and a vacuum valve to allow atmospheric pressure into the tank when the fuel level drops. if there is pressure when you open the fuel cap hours after shutdown, the evaporative emission system might be saturated or clogged up. see your competent technician