Gas leak i got a 1984 nissan sentra and the gas leaks a ton but only when you start it. the moment i shut it off it stops leaking. any ideas on how to fix that?

Yup, usually 2 straps around tank, or bolts into outer lip. have something to hold it when working on it & getting close to lowering it. You may only have to lower it to find problem. Also, if fuel pours out with key just in the on position, not start, then it will be electrical, and you'll probably hear a little hum from tank or close to. If mechanical (you should hope for mechanical), it won't pour out until engine is running.

Yup, usually 2 straps around tank, or bolts into outer lip. have something to hold it when working on it & getting close to lowering it. You may only have to lower it to find problem. Also, if fuel pours out with key just in the on position, not start, then it will be electrical, and you'll probably hear a little hum from tank or close to. If mechanical (you should hope for mechanical), it won't pour out until engine is running.

Pull back seat out first & see if there is an access spot to top of tank there by chance, if not, I'd lower it a little at a time, just enough to get to what I need to get to. You should have 3 lines, one for fuel to pump, one return & 1 for vapours. My guess is it's your return line, which just sends excess fuel back to tank. New piece of hose & a gear clamp may be all you need, here's to hoping. Just double check that you have a mechanical pump by looking at the lower part of your engine, for lines running up to your carburetor from it. Or follow your fuel line down to it. Here's a link for you to help.

http://www.autozone.com/shopping/repairG...


Pull back seat out first & see if there is an access spot to top of tank there by chance, if not, I'd lower it a little at a time, just enough to get to what I need to get to. You should have 3 lines, one for fuel to pump, one return & 1 for vapours. My guess is it's your return line, which just sends excess fuel back to tank. New piece of hose & a gear clamp may be all you need, here's to hoping. Just double check that you have a mechanical pump by looking at the lower part of your engine, for lines running up to your carburetor from it. Or follow your fuel line down to it. Here's a link for you to help.

http://www.autozone.com/shopping/repairGuide.htm?pageId=0900c152801ce5e8

I'm guessing that because of the year, and vehicle that the electric fuel pump is running at a fairly lower pressure than some of today's fuel injected systems. Instead of 40-60 psi, I'm thinking probably 5-10 psi.max. So here's what I'd try. Take a good look at the lines for signs of stains indicating that fuel has evaporated in that spot, due to leak.Measure size of lines, 1/4", 5/16", or 3/8". Buy yourself enough of fuel line hose, to be able to replace suspected problem areas, and some hose/gear clamps to fit on them. You may even find that the only problem areas are the short rubber pieces that are already there, and just need to replace them.Be real careful, don't forget your playing with gasoline here, so eliminate any source of spark , even disconnect battery once you've isolated your leak(s) so that no sparks can happen at wiring connections.Keep windows/doors open & well ventilated while doing this o.k., and any other common sense that comes in to play here. Any pinholes in metal line, cut a few inches either side, or at least enough to ensure it won't leak again, soon in immediate area of repair. Out with the bad, in with the new, and cut the new fuel hose long enough to slide a good couple of inches over each end of good line, slide your clamps over hose & install hose(s) . When you think you've got it all done, (hook up wires first at tank, then reconnect battery) & ready to test, throw a rag or something over the hole you were working at, just in case, so fuel doesn't shoot into interior if still leaking. Start car, let it run for about 1 or 2 seconds & shut it off. Have a look for any damp spots & repair as necessary if there is, but disconnect battery before you do. When ready, start the car again & have a real good look for a few minutes to be sure no more leaks. Take your time, clean all lines in area where connecting as best you can for good seal & to keep debris out of fuel lines & system. Grab yourself a new filter too, and when you've got all lines fixed, change filter, and hopefully you'll be on your way. Keep me posted will ya? Good Luck, work safe!

I'm guessing that because of the year, and vehicle that the electric fuel pump is running at a fairly lower pressure than some of today's fuel injected systems. Instead of 40-60 psi, I'm thinking probably 5-10 psi.max. So here's what I'd try. Take a good look at the lines for signs of stains indicating that fuel has evaporated in that spot, due to leak.Measure size of lines, 1/4", 5/16", or 3/8". Buy yourself enough of fuel line hose, to be able to replace suspected problem areas, and some hose/gear clamps to fit on them. You may even find that the only problem areas are the short rubber pieces that are already there, and just need to replace them.Be real careful, don't forget your playing with gasoline here, so eliminate any source of spark , even disconnect battery once you've isolated your leak(s) so that no sparks can happen at wiring connections.Keep windows/doors open & well ventilated while doing this o.k., and any other common sense that comes in to play here. Any pinholes in metal line, cut a few inches either side, or at least enough to ensure it won't leak again, soon in immediate area of repair. Out with the bad, in with the new, and cut the new fuel hose long enough to slide a good couple of inches over each end of good line, slide your clamps over hose & install hose(s) . When you think you've got it all done, (hook up wires first at tank, then reconnect battery) & ready to test, throw a rag or something over the hole you were working at, just in case, so fuel doesn't shoot into interior if still leaking. Start car, let it run for about 1 or 2 seconds & shut it off. Have a look for any damp spots & repair as necessary if there is, but disconnect battery before you do. When ready, start the car again & have a real good look for a few minutes to be sure no more leaks. Take your time, clean all lines in area where connecting as best you can for good seal & to keep debris out of fuel lines & system. Grab yourself a new filter too, and when you've got all lines fixed, change filter, and hopefully you'll be on your way. Keep me posted will ya? Good Luck, work safe!