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Old 04-17-2014   #7
Schrade
 
Join Date: Dec 2012
Location: NC
Posts: 1,783
Default Re: Fuel Tank Pressure

Quote:
Originally Posted by scottfab View Post
only thing I could find on gas cap pressure testing wast this from the EPA. It seems to allow for a certain amount of leakage.

Are people seeing a true pressure build up OR a vacuum build up?



Gas Cap Test
(1) Cap Installation. The fuel cap, or caps, shall be removed from the fuel inlet(s) and installed on
a portable or bench test rig using the adapter appropriate for the gas cap as specified in
ยง85.2227(d)(1)(ii).
(2) Leak Measurement. The gas cap leak rate shall be measured and compared against a 60 cc/min
at 30 in. WC flow standard. Pressure decay measurement using instruments with a 1 liter head
space shall be made from an initial pressure of 28 in. WC and be compared against a loss of 6
in. WC in 10 seconds.
(3) Cap Replacement. The fuel cap(s) shall be replaced on the fuel inlet and tightened
appropriately.
Anytime I have my front end up on ramps, and air temp increases 15' - 20' F, I start smelling strong gas near cannister while wrenching. I go to the back, loosen the cap, and A LOT of vapors release.

Makes me think that tank angle, and gaseous pressure increase, forces fuel through the EVAP line, instead of just vapors... (I keep the tank full too).

On LT1 top end rebuild, I was greeted on second day by steady drip of fuel from disconnected lines, whereas it was NOT dripping shortly after dis-connecting the first day.

Last edited by Schrade; 04-17-2014 at 02:23 PM.
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