How does fuel flow?

[88schwarz]

Hey folks. Due to corrosion and needing an increase in comfort/confidence level I replaced my hard fuel lines this weekend. Now the car will not start. Ran fine before and I'm sure it is because it is not getting fuel

The vent line that runs from the top of the tank to the charcoal canister I feel pretty sure I reconnected correctly. My question is about he path of the sending and receiving lines, as I may have them crossed up at the engine end.

Here is how they are currently routed. Starting at the tank end.

Sending line runs into filter/out of filter, then into hard line and then up around the engine and into the rail at the rear end of the rail (closest to windshield).

Recieving line runs straight into tank and then into hard line and up into the pressure regulator.

Should the sending line send fuel into the regulator first and then exit at the rear of the rail and into the receiving line?

Would this cross up make the car not start?


Thanks in advance. Car is an 88 325is

[jlevie]

You have the fuel lines correct. The fuel pressure regulator is on the downstream side and the supply side goes directly to the rail. If in doubt, pull the return line from the FPR, attach a piece of hose to the FPR and point that and the return hose into a bucket. Jumper the fuel pump relay and see which hose fuel comes out of. It should come out of the hose connected to the FPR.

[88schwarz]

Thanks Jim. I see your posts across the various e30 forums on the net and just wanted to say thanks for your clear and sound advice.

The car ran fine before I disconnected and reconnected the lines. How long should it take for the fuel pump to get fuel back to the motor? I tried starting several times but no luck. And didn't want to risk damaging the starter.

Runs with starting fluid.

[jlevie]

If the fuel system is working properly, the lines and rail will fill and hit normal pressure withing a few turns of the engine from completely dry. It doesn't sound like that is happening here, so I suspect the lines aren't correct. Try the test I suggested above.

For diagnostic purposes, enable the pump(s) by a jumper in the fuel relay socket. That avoids running the battery down by cranking the engine.

[88schwarz]

I had them backwards. Jim's diagnostic test worked and I had the car running in seconds. Thanks again.