evap converted to return with tank reg for free
 

This was done on a 2002 WS6. Should be the same system back to 97 firebird or camaro.

I've been searching around and found very little on this so here goes all the install info.
I pulled the fuel pump relay and started the car several times to relieve the fuel pressure.
Cut here. Remove the schrader in the fuel rail.

https://ls1tech.com/forums/attachmen...1&d=1395030642

Heat the tube with a hair dryer and shove a 5/16 barb by 1/4 NPT in there. For the fuel rail, I just happend to have a -4 swivel to 1/4 NPT laying around. You could probably use a cheap brass inverted flare. Next is the 1/4 NPT elbow. But I screwed up, I just ordered gauges so this will have to be changed to a T.

https://ls1tech.com/forums/attachmen...1&d=1395030642

Put it all together with sealant not thread tape.

https://ls1tech.com/forums/attachmen...1&d=1395030642

There is a factory bend in the tube. Heat it with the hair dryer and it will relax straight. And bend the line closer so it will reach.

https://ls1tech.com/forums/attachmen...1&d=1395030642

On to the back.
 

Locate these 2 fittings above the axle on the drivers side.https://ls1tech.com/forums/attachmen...1&d=1395031421

The one up top is the oem fuel return. It is a short 2' line that goes to a T. Disconnect it with a fuel disconnect tool, gray I believe. Disconnect the other end at the T with a 5/8 wrench. Remove it from the car and cap the T with a 1/4 NPT plug with LOTS of thread tape. It's actually some damn metric o-ring fitting but this will work. Run it in until it bottoms out. Try it without the tape first, by hand.

https://ls1tech.com/forums/attachmen...1&d=1395032211

The other one is the evap to charcoal canister line. Pinch it and pull to disconnect.

https://ls1tech.com/forums/attachmen...316_191240.jpg

Cut that plastic piece off with a utility knife. Unfortunately this one will prob be rusted. Clean it up good with a wire brush on a drill.

https://ls1tech.com/forums/attachmen...316_192056.jpg

Flush
 

Jam some old fuel line on there so you can flush that sucker. Mine was full of rust n shit and you'll be sending that into your regulator. I went to the fuel pump relay I pulled out earlier and put a jumper wire across the contacts to run the pump. If you can't read the relay schematic, jump the contact on the right furthest away to the contact on the left closest to you. Turn on the key. If you can't do this then just put the relay back in and cycle the key until its flushed.

https://ls1tech.com/forums/attachmen...1&d=1395033004

After a whole hell of a lot of bending...you have to straighten that 90 in the end, you can fanagle it into a really good position to connect to the return tube.

https://ls1tech.com/forums/attachmen...1&d=1395033235

Now that rusted pos may want to slip off and you don't want that shit. Tug and pull on it. Make damn sure it's going to stay. Run the fuel pump again and pull on it some more. Check for leaks on all the fittings. That shit is done and it was damn near free. You now have a full return system with a 60# reg in the tank. Now you can add an inline pump somewhere if needed instead of having to pull the tank or cut a hole in the trunk to get more flow.

Nice job. Great info.

bumped to the top with my new Walbro 400 lph turbine F90000262 fuel pump thread

https://ls1tech.com/forums/fueling-i...l#post18142640

Great writeup. Can I ask why you didn't decide to do an inline pump?

I went back and forth for days. On the same page of the walbro catalog with flow charts is a screw type external used on the Veyron. It would have been easier to install but only flows 330 and costs $200. I didnt want to risk noise, the filter, hoses and wires are ugly, and I really needed to get that regulator out of the tank and put an adjustable boost referenced at the rail. 2 birds...advantage of in tank.

Check this out. How to get your fuel pressure gauge to display through tuning software.

https://ls1tech.com/forums/18151976-post107.html

Update. This has been a trouble free mod but FYI. The evap line is a 20 psi restriction at a flow of 400 lph. Not an issue if you are using a fuel management unit but the back pressure causes a regulator to hold higher than optimal pressure at idle and lower than optimal pressure at wot.

It's not the evap line that's causing that. It is either your regulator or that combo of fittings where the shrader valve was.

I'm usually very thorough with my testing. Although I'm sure the Schrader port causes a restriction, that's not what the gauge is showing because the gauge is after that point. Here is a picture of the current setup. Adequately large 1/4 NPT Tee fitting with gauge sender on one side.

https://ls1tech.com/forums/attachmen...1&d=1400790024


Here is a shot of the test and results of the flow at this point without the return line but with all the fittings at the Tee. 0 psi

https://ls1tech.com/forums/attachmen...1&d=1400790024

https://ls1tech.com/forums/attachmen...1&d=1400790024

Here is a shot of the results WITHOUT a regulator. Only a 3/8 connector in it's place. Only the return line connected. As you can see. There is enough restriction to cause 16psi on the Tee.

https://ls1tech.com/forums/attachmen...1&d=1400790024

https://ls1tech.com/forums/attachmen...1&d=1400790024

Something else is hosed up in that return/evap line or where it returns into the tank. There's no way there is 16psi of restriction in that line...

Hey, believe me, I'd like to fix it. The tank end of the return is oem line. I used the oem plastic quick disconnect to connect to the hard line. I will redo that somehow. That fitting is tiny. Closer to 1/4 than 5/16.

I did a few mods to the connections on the evap/return line. I had reused the oem quick disconnect to hook up to the metal evap line. It wasn't 1/4, it was only 3/16 ID. And the metal line is only 1/4 ID.

https://ls1tech.com/forums/attachmen...1&d=1401178527

So I ditched it and just slipped on the 5/16 hose without a barb to connect too.

https://ls1tech.com/forums/attachmen...1&d=1401179460

Here's the test rig.

https://ls1tech.com/forums/attachmen...1&d=1401178529

And got my restriction down to 9 psi.

https://ls1tech.com/forums/attachmen...1&d=1401178529

There is another quick disconnect at the axle I'd like to replace but I'd have to replace the nylon hose all the way up to the top of the tank. I'll do that next weekend but for now 9 is much better than 16.

what happens to the EVAP solenoid and the line going to the intake manifold?

I used the port on the intake for a super strong BOV and fuel pressure regulator reference and removed the solenoid because I can turn the code off with hpt. Or else leave it alone or cap it. It really doesn't matter

Impressive work! Thank you for sharing and posting. Great write up!


.

Thanks man. That's was a fun project. That was a good full fuel return project for the $50 I had in it, including regulator. I miss that car sometimes. I did some crazy work to that car to only have kept it 2 years. I still talk to the new owner all the time.

I used the same line, but didn't go cheap. Converted it to AN with screw on adapters that don't let go.


https://cimg2.ibsrv.net/gimg/ls1tech...8fb2f4330a.jpg