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So, I worked on my S5 last week and the car is now running great! While I was upgrading some of my exhaust components, I noticed a faint odor of gasoline near the gas tank. Actually, this wasn't the first time that I smelled raw gasoline from the rear car, but I shrugged it off since others have complained of this too. After looking around, I noticed that one of the hard fuel lines at the left rear side of car appeared to be damp with fuel. I know that there's four hard lines that run along the inner left frame rail, and three are for fuel (i.e., supply, return and vapor) and one for the brakes. (I know my frame rails are going to $hit too, but that's another separate topic.) The leak doesn't seem too bad yet, but I eventually need to replace all these lines. I've already ordered the brake line, but the fuel lines are NLA from Mazda. So, I'll need to fabricate new hard fuel lines. I've posted a photo below looking forward at left rear wheel. My line #2 was the line that appeared to be leaking. Can someone please help me identify all these hard lines? Thanks in advance!
drop the tank
drop or atleast lower front part of the rear subframe
remove whole assembly of the feed/return/vapor lines as one unit and be done with it
anything else is just band-aid waiting for above mentioned steps to be done
Yeah, this job is on my "to do" list. I bought the brake line from Mazda. Bought the fuel vapor line from Mazda, which was the last one left in North America. Fuel supply and return lines are NLA from Mazda. So, I bought a kit from Summit Racing for making up fuel lines. I hate the thought of getting started. It's going to a lot of work.
Its not as bad as it seems, start with disconnecting hoses / wiring at the fuel pump hanger , so u can safely lower the tank. Having empty tank (there is draing plug) helps.
Once the top of tank is free, as far as u can reach (there will be one more hose to do once its lowered), support the tank and un-do front tank belt bolts. U dont have to worry about rear ones. Whole tank will tilt, un-do whatever is left and get it out of the way.
Good to have the car high enough to clear obviously.
This will show u whole assembly and job will start looking much easier. Rear subframe could be lowered just at front studs, but getting it back might be tricky, as it will swing back on the shocks. Exhaust might need to be dropped too, depending on what setup u run.
Of course, proper way is drop catback, disconnect driveshaft and drop whole subframe with diff, giving u chance to do proper anti-rust treatment for whole rear.
Once rear part of piping assembly is free, front hoses are easily to be reached from engine bay (u could start whole job there, before raising the car) and u can remove it all together with fuel filter (good excuse to change that).
I think you're getting ahead of yourself. Locate the source of the leak first.
The best way to start is to attack the tank from the top by removing the Fuel Pump hangar cover so you can see if the rubber lines at the hangar elbows are leaking. You need to do this if you're going to remove the tank anyhow, so might as well do it first.
BTW hardlines would have to be pretty badly rusted to justify replacement.
I think you're getting ahead of yourself. Locate the source of the leak first.
The best way to start is to attack the tank from the top by removing the Fuel Pump hangar cover so you can see if the rubber lines at the hangar elbows are leaking. You need to do this if you're going to remove the tank anyhow, so might as well do it first.
BTW hardlines would have to be pretty badly rusted to justify replacement.
My fuel return (low pressure) line has a very slow leak (actually a very slow drip) at the point as shown in my photo in original post. The leak is right at the 90 degree bend. The gas leak is so slow that it actually evaporates as fast as it's leaking.
I'm thinking that I can probably get to lines at top of gas tank through the port hole in the rear hatch without dropping the tank. But if I need to do so, I'll drop the tank.
07-28-19, 05:47 PM
