14
Jan
High pressure in a cars gas tank may cause dangerous conditions. When sun hits the fuel tank in the morning tank warms up and pressurizes the tank.
When you open the cap there is much more pressure than there has ever been before.
Pressure buildup in gas tank. A cars gas tank will build pressure under normal operating conditions. High pressure in a cars gas tank may cause dangerous conditions. High gas tank pressures in a car may cause gas tank bulging fuel line leaks fuel pump problems lack of fuel to the engine for combustion dangerous conditions when opening the gas tank filler cap and potentially create fire hazards.
Tailpipes running next to the tank plus road heat plus engine heat due to the car direction and high ambient temperature all heat up the air in the tank. The fuller the tank the less pressure buildup. Air expands more than a liquid.
You might try a 71 later gas cap. Reason for Too Much Pressure in the Gas Tank. Fuel pumps feed fuel to engine carburetors by pumping it from fuel tanks.
Removing fuel causes a vacuum that if not released or maintained at the correct pressure becomes too great causes pump failure and starves the carburetor of fuel. Until this vacuum is released the car will not run. The canister should absorb fumes from the tank and thereby relieve pressure at all times if is operating properly.
This is the very reason it has stored fumes to release to the engine. I think that if there is ever any pressure buildup in the tank then the canister is blocked. Shouldnt happentank has a vent line and its obviously blocked or nipped somewhereusually happens when lowering the tank after doing work under it.
Ve pressure puts you at risk in so many waysopening the cap releases a cloud of flammable gas which could easily be ignited innocently by a nearby smoker etcalso pressurises the seals on the tank which arent intended to withstand pressureonly for holding back the fuel-ve pressure from a lack of air getting into the tank. Most likely you are correct in your thought of a blockage in the vapor can system. Personally I have never had a pressure problem like this just the opposite.
A bad gas cap not venting caused a vacuum in the tank and the fuel pump couldnt draw enough fuel. That typically happens when you run your tank low on gas. The vapors build up.
It also happens when one drives very erratically with low fuel levels. I believe the gas tank is actually not under pressure but under suction. When emptying the tank of fuel it has to replace the space where the fuel used to be with air.
If there is not proper venting of the fuel tank to allow this then I believe it will be under great suction and when you take the gas cap off you are actually hearing air going into the gas tank rather than leaving it. 5 Mar 20 2012. I get the pressure buildup in both my Ninja and Concours occasionally But I would say it is not normal.
The only time I had gas overflow was when I filled it considerably above the collar and we sat at the gas station for about 20 minutes right after that. The EVAP system can test itself one of two ways either through pressure in the tank or vacuum. Either pressure or vacuum will cause a pressure release sound as you open the fuel cap.
If pressure is present it can escape through a whoosh type sound. If vacuum is present atmosphere can escape into the fuel tank through a whoosh type sound. Its very hard to distinguish between the two unless you know how.
A cars gas tank will build pressure under normal operating conditions. High pressure in a cars gas tank may cause dangerous conditions. High gas tank pressures in a car may cause gas tank bulging fuel line leaks fuel pump problems lack of fuel to the engine for combustion dangerous conditions when opening the gas tank filler cap and potentially create fire hazards.
The high pressure is normal not only is the air hot but the hot engine is like a heater right under the tank. Yeah itll build pressure. If its hissing Id keep an eye out because the diaphragm inside the vent apparently isnt stopping the flow.
It may allow rain water in which is bad. What can cause excessive pressure to build in the gas tank. When I stop my car there are gas vapors coming out of the vent line located under the filler cap just behind the rear wheel.
When you open the cap there is much more pressure than there has ever been before. When you drive the car you get a slight smell of gas inside the car. The gas cap is desinged to vent at a given pressure.
If the tank is almost empty it will have more volume to vent even if it has no more pressure that is normal. While it is hard to say I would not consider your expereience to be an indication of a problem. If you really want to try something try a new fuel cap.
Pressure happens as tank heats up from warm gasoline recirculating back from the engine return line bypass which in turn increases the partial pressure of the gasoline that creates the pressure you notice when you remove the cap. Pressure build up in gas tank. Jump to Latest Follow 1 - 7 of 7 Posts.
Joined Oct 27 2010 155 Posts. Discussion Starter 1 Mar 20 2012. Dont overfill your gas tank.
The gas coming out of the ground is much cooler than the air around your gas tank. The liquid gas will warm up to the ambient air temperature and expand until the gas builds up pressure and leaks out your overflow or gas cap if you loosen it. Always leave an airspace when filling fuel tanks to compensate for liquid gas expansion.
When I ride my 08RSVR my tank builds up pressure. The carbon canister has been removed and both vent lines coming out of the tank just go straight to the ground. I have checked and both lines are clear when they are removed from the tank nipples.
I can easily blow into the tank on the right most nipple as you look to the rear of the bike but struggle to get air in the tank thru the nipple. What causes excessive pressure to build up in the fuel tank of my 1996 Ram 1500. When I remove the fuel cap to refuel there is an excessive amount of air escaping from the tank.
I know that some air would be normal but there is a lot. Nothing like I have heard on any vehicle at any time. The fuel pump gas cap and fuel evaporator cylinder.
When sun hits the fuel tank in the morning tank warms up and pressurizes the tank. Think of a plastic fuel can that swells up when left in the sun This pressure build up causes fuel to leak out from the top of the fuel sediment bowl. Not sure if a fitting or seal or If I loosen the fuel cap overnight no leak the next day.
Usually a sign of the charcoal cannister getting plugged with gasoline or water. The vacuum collapses the sensor tube for the fuel guage and youre screwed. Remove the charcoal cannister if you still have one.
At least on the 1150 series. This can be caused by a problem in the fuel pressure check valve of the fuel pump. Have a pressure leak down test run by a shop if the system is losing pressure then the pump assembly must be replaced.
The fuel pump is located inside the gas tank and is electric. If you were re-jetting because of fuel mileage you have found your issue. The tank is pressurizing causing the fuel to be forced through the carb because it has no were else to go.
Not sure how the Heritage is vented maybe cap maybe through a vent tube that runs down in front of the seat.