Question about 2005 kawasaki EN 500 Vulcan

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My gas tank is building up excess pressure when the bike is on for a while or after riding only short distances. This causes a high pitched squeal when the pressure gets too high. If pressure is not released by opening the gas cap after riding, the bike leaks gas that backs up into the carbeurator and air filter (from what we can tell). What would cause the gas tank to build up so much pressure?

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The tank is building up too much pressure because the pressure relief valve in the gas cap is blocked.All gas caps are vented-(otherwise the tank has to be somewhere- like on Canadian models with fuel evaporative systems on them).
clear the blockage or replace the cap & you should be fine.
Under most roadbike gas caps is a cover held in place with two screws-remove them to dissasemble the cap & clear the blockage in the cap vent
If yours is a Canadian(maybe US models are the same)-model then the problem is in the fuel evaporative system. Check out this link.

Hope this is helpfull.
Kind regards Andrew Porrelli

Posted on May 17, 2011


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Posted on Jan 02, 2017


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Gas is being forced out of the fuel tank when the vehicle is running.

A defective fuel pressure regulator (located on the fuel rail) may have blown the gasket on the
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Another thing to check - the car's computer may have posted
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Fuel system is too rich (fuel pressure too high, fuel pressure regulator leaking, or one or more fuel injectors sticking/leaking)

HO2S element is silicon, water or fuel contaminated

HO2S signal circuit is shorted to system power (B+)

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Manufacturer's recommendation – Short distance city riding below 100kph. Light off-road use ie. Small rocks, gravel. If the weather/road conditions vary a lot.

30% above recommended pressure – High speed road use. Long distances in warm weather on good quality roads. Go 40% if the conditions are the same but the bike is fully loaded with carriers.

15% below recommended pressure – Short distance riding in cold winter temps. Short distance on wet roads. Off-road, average gravel/rocks and some wet mud.

40% below recommended – Slow off-road riding in very loose dirt, sand, with lots of rocks. Tires will heat up quickly if the pace is picked up which will loose grip and cause accelerated wear.

60% below recommended – Very slow, loose dirt, deep sand (dunes). If tires slip on the rims you need to increase pressure.

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Hope this helps and you vote for me :)

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