Hey all,

Replacing all of the soft fuel lines in my car today. I am not sure of the size and would like to verify that I am right:

Return lines: 5/16" ID
Send line (from tank): 1/2" ID
Filter line to pump: 3/8" ID
Fuel rail and engine bay lines: 5/16" ID

Please let me know if I am right with these measurements. Don't wanna mess this up, as the fuel system is pretty important.

 

If you have lengths of all those sizes, you'll just be replacing like for like. The more important thing is that you're using FUEL INJECTION HOSE vs. Standard Fuel Hose. These days, rated FI hose is far more common, but just make sure that it says right on the side that it's for fuel injection pressures. I bought an engine from a guy that used standard carbeurator fuel hose (*low pressure) for the connections to the Fuel Rail and when it pressurized, it expanded enough that the pinhole leaks sprayed fuel like a mist. Keep in mind that the distributor cap is only about 8" away from the fuel rail on an SE...

At the back of the car, the Fuel Tank to Fuel Pump connections are large, as the pump needs volume at low pressure, gravity fed from the tank. From the Fuel Pump to the Fuel Filter next to it, that line is smaller ID and has banjo fittings, because all after the Fuel Pump is high pressure. Don't forget to remove the plastic filter screen in the big line going into the Fuel Pump inlet side and replace it in your new line. This screen filter is to catch big debris before it gets to the pump. The EFI Fuel Filter must be the all-metal, high pressure filter style and filters out fine debris before they get sent through the hard lines to the Injectors. Fuel return lines are the same size as feed lines to the Fuel Rail. Some of these can't be replaced without dropping the Fuel Tank, as they're on the top of the tank and inaccessible.

 

https://www.rx7club.com/1st-generati...outing-840141/

 

Update to this post in case someone comes after me to replace their lines on a GSL-SE:

I did end up getting all of the fuel lines replaced. It was not very hard, and took around an hour.

The correct sizes are:

Send line (from tank): 1/2" ID or 12mm
Return lines: 5/16" ID or 8mm
Filter line to pump: 5/16" ID
Fuel rail and engine bay lines: 5/16" ID

You will need around 1.5-2ft of 1/2" ID fuel line. You will also need AT LEAST 5ft (I would get 6ft) of 5/16" ID fuel lines. The automotive store I went to was running out of their 5/16" line and just gave me the last of the spool. The employee made sure to measure the line so I would get at least 5ft, but it was a tad bit longer. I ended up using most of the length of the fuel lines.

I believe the fuel pump outputs around 50psi. I chose to go for 100psi line just to be safe. The 5/16" line was 225 psi as that was the only thing that the automotive store had.

You CAN get metric fuel lines at some car dealerships, however I have heard that some of the BMW ones don't last as long in the RX7. Not sure how true this is. I doubt it will be a real problem as the fractional sizes are very close.