edekalil Posted June 30, 2015 Report Share Posted June 30, 2015 Just wondering there should be a vent for the gas tank but I am not sure where it is. My old 70/510 builds up pressure in the tank. When you loosen the gas cap to will release pressure that has built up. A vent is supposed to prevent that I believe. Anyone know where it is located I think mine may be clogged. Quote Link to comment
datzenmike Posted June 30, 2015 Report Share Posted June 30, 2015 Is it air being sucked in to replace the fuel removed? There's no way really for pressure to build. Maybe a small amount from evaporation. Does your car require a vented gas cap??? I had a gas tank implode on me once from a non vented cap. I thought air was rushing out every time I gassed up but it was whooshing in. I think all years had a vapor vent line to the engine. Early ones stored the fumes in the crank case and later in a charcoal canister. Quote Link to comment
heywier427 Posted June 30, 2015 Report Share Posted June 30, 2015 I always see this on ebay:http://www.ebay.com/itm/Datsun-510-1968-73-Gas-Tank-Vent-Can-/271910751485?hash=item3f4f24ccfd&vxp=mtr It mounts above the gas tank. There are 2 studs on the rear seat cross brace. I vented mine to the ground. Way easier :) On another note. I almost 100% sucked my gas tank shut when my vent went bad on my vw. The injection pump was strong! :) I filled it with compresed air, and it now has 11 gal. capacity, instead of 10. Yay :) Quote Link to comment
datzenmike Posted July 1, 2015 Report Share Posted July 1, 2015 On another note. I almost 100% sucked my gas tank shut when my vent went bad on my vw. The injection pump was strong! :) I filled it with compresed air, and it now has 11 gal. capacity, instead of 10. Yay :) Me too! Finally I ran it too low and it imploded. Flattened it, bent the pick up tube and sender so it sucked air. Acted like it was empty. Long story but added enough gas to get where I was going. Could not find ANY cars older than '95 in Ontario, gone to scrap. Ended up removing and plugging all holes and used my dad's neighbor's compressor. Tank 'blew up' like a balloon, took any wrinkles out and works just fine. It was scary hearing all the pings and pops as it expanded. Quote Link to comment
shacks510 Posted July 1, 2015 Report Share Posted July 1, 2015 I have mine vented under the car too. $24¢/foot for gasoline fume tolerant tubing. Four feet will be enough. Quote Link to comment
edekalil Posted July 1, 2015 Author Report Share Posted July 1, 2015 Mine has the small canister above the tank I guess it's filed with charcoal. I haven't driven the car a great deal. I was able to drive it this last weekend so the sea dome has probably desolved the old gads that had turned into jelly and was clogging the fuel line. It sat more than ran for a while. I'm guessing when it was sitting with the vent probably cloged due to a dirt dobber when the gas got warm it probably expanded and did not vent. And the issue with the car not having the power it should have is due to it not venting and starving it of gas. I will have to look at that this weekend and figure it out. Thanks you all for the info, so far I have not collapsed my tank. Quote Link to comment
datzenmike Posted July 1, 2015 Report Share Posted July 1, 2015 The tank above the main fuel tank is just space for fuel expansion and a place for fumes and bubbles to collect and settle before being piped to the guide valve and storage in the crank case (engine off) once started, the fumes would be sucked into the intake through the PCV valve. Quote Link to comment
edekalil Posted July 2, 2015 Author Report Share Posted July 2, 2015 Thanks for the info, I will check the PVC valve and try to figure out the issue here this weekend when I got back. Quote Link to comment
edekalil Posted July 3, 2015 Author Report Share Posted July 3, 2015 Come to think of it, someone had done some work on the motor befor I got it. The exhaust manifold has been changed to a later one with the emissions tubes comming out (they just cut them and bent them shut). I will fix that, I will just have to locate some studs and nuts that go into the end to hold the down pipe. Some one could have plugged up something on the engine end and that may be it. Quote Link to comment
yellowdatsun Posted July 4, 2015 Report Share Posted July 4, 2015 Mine used to do this as well. Drill a tiny hole in your gas cap to let air in as the fuel gets used up. Quote Link to comment
edekalil Posted July 5, 2015 Author Report Share Posted July 5, 2015 I found this under the hood. I believe this is from the tank and Clem just looped the hose closing the vent. I undid the hose that is looped and I could hear it vent. I will run it a little and next week try to get time to straten it out but so far seems to be working. Gotta get back befor the rain. Quote Link to comment
edekalil Posted July 5, 2015 Author Report Share Posted July 5, 2015 So far seems to be working fine. There was no pressure when I took off the gas cap. 1 Quote Link to comment
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