today i was driving my corolla and the brake peddle started sinking to the floor, and by the time i got home, there was very little brakes left. the master cylinder was very low but i did not see any fluid at any of the wheels. so i added some brake fuild, pumped the peddle and backed the car up some. i saw some brake fuild on the ground where the car was so i checked under the car where the driver's side rear passenger sits and this is where the brake lines and the gas lines all run thru a conduit to the front of the car. 4 of the 5 metal lines are rusted thru. i pull a few lines to the side and all of a sudden gas is streaming out of 2 of the 3 gas lines. my question is, the fat gas line with the brake line style connection :: what pressure is the gas under in this line when engine is running? can i use rubber fuel hose for a short time to take car to mechanic?

If it's fuel injected expect 50psi.

50 psi +-, ok, thanks. i wonder at what psi must lines be metal??? (rhetorical)

anyway, i replaced the 3 rusted thru metal fuel line sections with rubber fuel lines and hose clamps - ain't pretty - but seems to be ok for now.

next step is to replace 2 rusted thru sections of brake line. i need to wait for napa to open tomorrow to see if they have 4.??? mm toyota corolla brake line in stock - and - if they have a metric bubble flare tool and unions, in stock. seems the standard smallest size bubble flare is 4.75 mm but i think my brake lines are a bit narrower??

Help, i cant stop my Toyota

Sounds familiar. If you cant get the flare kit, i'm sure mcmaster carr has it, but it probably won't be cheap.

yep
http://www.mcmaster.com/#tube-flaring-tools/=8ben7o

not terrible i guess.

Perhaps rhetorical, but since you ask - CIS lines are around 75 PSI and often plastic.
MFI lines from the injection pump to the injectors run about 300 psi and are nylon on the race cars although they are steel (like brake hard line) on the production cars.

So based on that, plastic looks to be OK from a functional standpoint up to at least 20 Bar.

here is the non metric flare tool i bought this morning because it said that it can do equivilant 4.8mm - but 3/6 is too small and 1/4 is too large.

Make sure you are using Fuel Injection hose and not low pressure hose.

well i decided to see how 3/16 would do. not bad for first try.

Japanese ("import") brake lines use a different flare than European brake lines, and sections in a variety of lengths, including female/female couplers are available almost everywhere where auto parts are sold. There's no need to make your own, and the replacement lines are made to be bent as needed, unlike the original pipes. Safer and more reliable, too.

As for the fuel lines, modern Asian and American EFI systems run at surprisingly low pressures, IIRC.

The Cap'n