Fuel line question (pic)

[Donedreamin]

Hey guys,

 

I'm trying to diagnose a problem, I'm running out of fuel just under half tank and my belief is the pressure and return are switched around. 

 

The pressure is the top one and the return is the closer one; 

 

[TENDRIL]

the return is/should be the bigger one

[Donedreamin]

The bigger one is currently the feed, here's a couple better photos. 

[TENDRIL]

well the line on the right (against the frame rail) should be your return and your saying that is the feed? so switch them and run it, let us know  :thumbup:

[MikeRL411]

What car?????????????

[TENDRIL]

Z car is what it looks like?

[Donedreamin]

Last summer i purchased my first Z, according to the ownership it's a 77' and it's a 10/76 on the door. When i test drove it, it had a small misfire in the top end. 

I figured it would be an easy fix and a good way to get my hands dirty. Well it started to get worse overtime, to the point where it was barely driveable. I narrowed it down to a fuel problem and hooked up a fuel pressure guage inside the car and whenever it would bog out the fuel pressure would drop below 25psi. I also by-passed my fuel dampener and noticed the pump's tone it emits would change whenever it would start to bog so i assumed my pump needed replacing. This week i changed the pump and fuel filter and it does the exact same thing! Not to mention I'm also running out of gas just below the half tank marker, but it's always been like that. 

Here's a video i took yesterday of it bogging and a picture of the car.

 

I also checked the TSRM and it has a diagram of the pressure and return being side by side and not one above the other, i'll keep you guys posted.

[Mannyvig]

The bottom one should be the feed line.

[Donedreamin]

How do you figure? The top one is 10mm and the bigger one, you would think that would be for the feed. Correct me if i'm wrong

[Interrobang]

You say "Runs out at half tank", do you know this for sure? As in, if you keep it above 50% full, it runs?

 

Get the FSM. Don't assume your problem is just the pump or line. Might be the fuel pump relay, or EFI relay cutting out if it fails after running a certain amount of time. You might want to re-install the fuel pressure regulator. This is one of the essential parts of the EFI system, won't run right without it.

[Donedreamin]

My FPR is currently installed, I found that it runs out of gas just under the half way point the hard way. It runs above 50% and as it gets closer to running out it violently starts to bog out. 

I was thinking of just running 12v straight to the fuel pump..

[Mannyvig]

Maybe because I looked at my car, which runs below half a tank.

[TENDRIL]

The pressure line is the smaller one the return is the bigger one, it might make sense for the bigger one to be pressure but its not just switch the two lines on you tank in the origanal photo, and once you find out that you can go below half a tank(which you should be able to once you SWITCH the two lines) than we can start to help you with the other problems,

[TENDRIL]

My FPR is currently installed, I found that it runs out of gas just under the half way point the hard way. It runs above 50% and as it gets closer to running out it violently starts to bog out. 

I was thinking of just running 12v straight to the fuel pump..

its doing this because its still catching fuel that is swishing around but the tube is not submerged

[Interrobang]

TENDRIL may have something there. You may have a messed up or clogged fuel pickup in the tank. Never dropped mine, but I imagine it's not impossible.