Replacing return hard lines in tank

[vavJETTAw36]

There are two opaque return hard lines in the tank that go to something near the back (towards trunk) and they are kinked. I have a thread entired "Rich Fuel Trims" so if you are interested in reading it please do. Just do not feel like giving that back story.

Anyways. Can anyone shed any light on how I can fix it? If I can buy the materials separately, etc. Any schematics out there too so I know what everything looks like in there?

[RocksForsSale]

I think that's for the evap system. Does it go to under the spare tire well in the center? There's like a pump back there or something.




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[vavJETTAw36]

Yes, exactly.

Can I cut the return line and drain right into the tank or wilk this F up the evap system royally?

[vavJETTAw36]

Anyone?


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[vavJETTAw36]

Should I be able to cut the lines before the kinks and allow the fuel to drop into the tank as opposed to running to the back of the tank and doing whatever it does? It obviously drops into the tanks somewhere. I stopped ripping at the lines because I didn't want to hurt whatever they attach to. Not familiar with any fuel tank related components with exception of the pump.


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[Bordom]

Should I be able to cut the lines before the kinks and allow the fuel to drop into the tank as opposed to running to the back of the tank and doing whatever it does? It obviously drops into the tanks somewhere. I stopped ripping at the lines because I didn't want to hurt whatever they attach to. Not familiar with any fuel tank related components with exception of the pump.


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I ran the return line straight to the blue cap without the line in tank connected. You'll hear some fuel splashing in tank when shutting off the car. Didn't get any codes for anything

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[vavJETTAw36]

I ran the return line straight to the blue cap without the line in tank connected. You'll hear some fuel splashing in tank when shutting off the car. Didn't get any codes for anything

Everything graciously mispelled by Android

Awesome! Means I can cut it before the kink (about a foot of line after the blue cap) and it should have enough line to dampen the splashing


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[Bordom]

Awesome! Means I can cut it before the kink (about a foot of line after the blue cap) and it should have enough line to dampen the splashing


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Yeah, you'll be fine.

I'm pretty sure that was designed to route to the other side of the tank so that it feeds the pump that balances out fuel in both sides of the tank.

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[zillarob]

You can cut the return off and just dump it in, but be careful the 1st few times you run the tank down.
Iirc, it runs down to some witchcraft gizmo that dumps in on top of the basket to keep it full.

Not going to claim to know exactly what devilry is happening there, but I could see it being some kind of vac jet pump contraption that is trading some extra psi on the return in order to pull a larger volume of fuel into the basket from the deep dark corners of the tank.

I think if I were going to try something like you are talking about, I would just unplug the return hose and run a hose from that port and dumps on top of the basket. Basically just bypass that funky gizmo that hangs out on the pside of the basket and see how it goes.


If the return was the prob, I would think you would see gnarly fuel pull at idle, but it would diminish as rpm and load went up.

[vavJETTAw36]

You can cut the return off and just dump it in, but be careful the 1st few times you run the tank down.
Iirc, it runs down to some witchcraft gizmo that dumps in on top of the basket to keep it full.

Not going to claim to know exactly what devilry is happening there, but I could see it being some kind of vac jet pump contraption that is trading some extra psi on the return in order to pull a larger volume of fuel into the basket from the deep dark corners of the tank.

I think if I were going to try something like you are talking about, I would just unplug the return hose and run a hose from that port and dumps on top of the basket. Basically just bypass that funky gizmo that hangs out on the pside of the basket and see how it goes.


If the return was the prob, I would think you would see gnarly fuel pull at idle, but it would diminish as rpm and load went up.

Rob,

At this point im not 100% sure thats the issue but I cannot explain why its such an intermittent problem with my trims going up and down with this tune in. But one thing is for certain, the pressure is higher. Before I found the issue with the return line, I pulled the line off the blue cap and used a barb fitting to run a hose to a gas can and my pressure went down to 52ish. 60 is what it is reading right now and its the only thing that tangibly is wrong with the car. So I will attempt to fix it and check it off the list.

Not following you about the "but be careful the 1st few times you run the tank down" suggestion.

I am wondering if I can keep one of the lines attached (with the slight kink) and cut the other one and run that over the basket. So kind of allowing it to continue to fill the basket but also gravity feeding from the top. But not sure if the individual line is large enough to reduce the pressure completely.

I figure it this way. I have a kinked hose that I cant repair so ive got nothing to lose cutting it. Or, if I think I can salvage it, unplug the hardline and I can run a separate new line as an experiment and if it fails try something else.

[zillarob]

I think like boredom said, good chance that gizmo is to pull fuel from places in the tank that fuel might not be able to reach the basket area from gravity alone.
You should see the crazy nasa space shuttle setup in a d2s8, I think there are like 5 of them things in there.

The sender is in the basket area so may not be a prob, but I think I would play it safe the 1st few times you ran the tank low to make sure the gauge is accurate.
Similar to people putting in fuel pumps and running out of gas a 1/4 tank because they didnt push them down far enough.

Sure you know all this already, but just to be safe.
Fuel psi changes around with mani pressure. The fpr just keeps fuel at the rail 4bar above mani psi.
I use a differential psi guage (psid) when testing so I dont have to deal with that hard math number thing
It has 2 ports (1 to the rail, and 1 to the fpr vac hose) and tells you the difference between the 2. It should stay at 4bar the entire time.
If it goes up at idle, the return is prob restricting it. If it falls off on the big end, need moar pump.

[vavJETTAw36]

I think like boredom said, good chance that gizmo is to pull fuel from places in the tank that fuel might not be able to reach the basket area from gravity alone.
You should see the crazy nasa space shuttle setup in a d2s8, I think there are like 5 of them things in there.

The sender is in the basket area so may not be a prob, but I think I would play it safe the 1st few times you ran the tank low to make sure the gauge is accurate.
Similar to people putting in fuel pumps and running out of gas a 1/4 tank because they didnt push them down far enough.

Sure you know all this already, but just to be safe.
Fuel psi changes around with mani pressure. The fpr just keeps fuel at the rail 4bar above mani psi.
I use a differential psi guage (psid) when testing so I dont have to deal with that hard math number thing
It has 2 ports (1 to the rail, and 1 to the fpr vac hose) and tells you the difference between the 2. It should stay at 4bar the entire time.
If it goes up at idle, the return is prob restricting it. If it falls off on the big end, need moar pump.

Rob,

Could I not find the same difference by using my standard gauge and pulling the hose at the FPR? When I do that, it jumps to about 67ish psi. I would think it really should never exceed 4bar without manifold.

The kinks that I am seeing in the hose are like if you tried to kink off a garden hose, they are bent in half.

Completely understand now about running out of fuel. I can carry a couple gallons of fuel around just to see if I can get down to my normal refill point.

[zillarob]

That sounds right and should be fine to check at idle. Should stay 4bar above atmosphere, or ~58psig.
Being able to see if there is any variance through the rpm/load range is nice also if you can swing it, but that takes math or the psid gauge.

I think if I were you, I would just unplug the return connector from the bottom of the lid and run it to see if the trims perk up.
Keep the fuel level above the basket so no chance that something goofy with being unhooked is affecting what you see.
I think above 1/2 tank should have the whole works submerged.

[vavJETTAw36]

Awesome. Thanks as always rob. I will try that and let you know.

Currently my boost Gauge is getting fuel pressure and wideband integration. But hopefully in a week or so I'll have it. Once that is in ill be able to monitor pressure from in cabin through rpm ranges. But I ain't waiting that long to try your recommendation so it might not even be necessary



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[vavJETTAw36]

Guys, I popped the return line off and the idle pressure dropped from 60 to 54psi. Also let the car idle and ran the fuel out by draining to cans to see what the new "refuel" point was and there doesnt seem to be a change.

Took it out for a drive and my trims stayed pretty much at -4 on both banks. I will repeat this tomorrow and the next day to see if it stays this way. AFR's seem to be fine. WOT is a little rich but better rich than lean :)

[Corradovolksb]

Man that's awesome you might have found your issue.

[vavJETTAw36]

Man that's awesome you might have found your issue.

Haha brad I hesitated to post but did anyways. Feeling pretty comfortable that I've solved my issue but you know how it goes. Though, I do believe the intermittent nature of this issue was purely caused by the hoses bouncing and floating. We'll see by the end of the week :)


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[erykv1]

I need to go check mine now, lol.

[vavJETTAw36]

I need to go check mine now, lol.

Cha having issues with?


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[Devious27t]

Kudos to you for sticking it out and finding the root. Most people would've given up


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[S4James]

my 2c on these lines:

1: with those lines kinked I ended up burning my walbro fuel pump.. even after fixing the lines the pump was ruined. Cost me thousands and a year of fussing around chasing ghosts because nobody was competent enough to recognize the fuel pump as the core issue. Bottom line, ensure that pump can still deliver at high loads once you sort things out.

2: repair them by cutting out the kinked sections and slip a couple male-male couplers in. Once they are kinked they are weak, and will naturally kink right back if they are even slightly bent in that direction.

3: the return line directly feeds the basket assembly and that helps keep the fuel where it is supposed to be when cornering with lower fuel levels.

[vavJETTAw36]

I tried using some male to make barbs and the problem is that they are so small inside they create a pinch of their own. Right now the pump is shooting straight down onto the basket but not sure if it's going right in. I'll watch my pressure to make sure pump is healthy

I think I'll add a line running down into the basket and allow the other line to spray wherever it wants. Or, instead of male to male couplers, I'll slip a hose over the lines to couple them.


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[vavJETTAw36]

Kudos to you for sticking it out and finding the root. Most people would've given up


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Lol, I wanted to give up but the next day id feel encouraged to get to the bottom of the issue. My wife certainly wasnt helping the situation either asking me why I spend all my free time working on the car. I had to explain to her many times that there was an underlying issue the car is compensating for and that I had to get to the root of it. Too much money involved in the whole ordeal not to.

[S4James]

women are fucking horrible for this. They think all your free time should be spent on them. Or at least things they care about.

[CJ_]

This was mine a little while ago:





So did you just end up taking the return line off the bottom of the cap and it just shoots straight down into the tank? I straightened mine out but like what someone said earlier, once theyre kinked they become very weak. My idle pressure is still in the high 60s so I'm wondering if I can bring it down some

[vavJETTAw36]

This was mine a little while ago:





So did you just end up taking the return line off the bottom of the cap and it just shoots straight down into the tank? I straightened mine out but like what someone said earlier, once theyre kinked they become very weak. My idle pressure is still in the high 60s so I'm wondering if I can bring it down some

CJ, I started by chopping about 5 inches from the blue lid and then chopped passed the kink. I even went beyond that and cut out any extra so it wouldnt kink when i pushed everything down. Started by coupling them back together with barbs but the barbs have such a small orffice that I beleive they created a pinch this increased pressure. I said screw it and pulled the line off entirely. I pulled the connector and 5 inches of line out of the car for now. Now, the fuel dumps straight down around the basket. But what I think I am going to do is put the connector back on the tank side of the blue lid and run one line (5/16 inch ID hose over the clear line) down to the basket and allow the other to dump wherever. OR I might use the 5/16inch hose to couple the oem lines back together and run it like it was.