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Fuel Return Line?

43K views 84 replies 26 participants last post by  01 SolarYellow 
#1 ·
Well, i went out and bought 14ft of fuel hose, as well as fittings, and now my only question is this: What do i need to modify in the pump housing to complete the return assembly?

I tapped the top of the housing and put the fittings in, but where do i need to run this line to? I've tried searching, but anytime i click search, or go to advanced search, i get the good ol "Server is too busy" message (webmaster, you gotta do something to fix that, its been killing me lately).

Any help you folks can give me would be greatly appreciated.

Also, i have a bit, i have a tap, now how do i get access to the damn drain hole in the motor? :lol: Drop the pan and do it that way? Lemme know folks.
 
#2 ·
Seven said:
Well, i went out and bought 14ft of fuel hose, as well as fittings, and now my only question is this: What do i need to modify in the pump housing to complete the return assembly?

I tapped the top of the housing and put the fittings in, but where do i need to run this line to? I've tried searching, but anytime i click search, or go to advanced search, i get the good ol "Server is too busy" message (webmaster, you gotta do something to fix that, its been killing me lately).

Any help you folks can give me would be greatly appreciated.

Also, i have a bit, i have a tap, now how do i get access to the damn drain hole in the motor? :lol: Drop the pan and do it that way? Lemme know folks.
Here's what you need to do to the fuel pump assembly.

1. Drill a hole in the plastic fuel pump assembly.
2. Get a bulk head fitting and install the fitting on that new hole.
3. Install the return line from the FPR to the end of the fitting that's exposed.
4. The other end of the fitting that will be in the tank needs to connect to the white ventricle.
5. Cut the line that's connected between the stock FPR and white ventricle.
6. Either pinch the nipple that is now exposed on the stock FPR closed and weld it shut or get 1/4" fuel line, 1/4" bolt that has no threads on the shoulder. Cut off the threated area of the bolt, insert the bolt in the 1/4" line and put a hose clamp on it. Put the other end of the rubber line on the stock FPR.
6. Run rubber line from the bulkhead fitting to the end of the white ventricle that the stock FPR was connected to.
 
#3 ·
Tap the top front of the rail and put in the fitting. Then from the rail the hose goes to the FPR. Then from the FPR the return hose goes back to the pump assembly
 
#6 ·


alright, what do i do to those? Im guessing 3 is the one i pinch shut and weld tight?

What about 1 and 2, which of those gets the return hose?

Thanks again for the help.
 
#7 ·
from the explanation, you simply 'take out' the stock fpr out of the equation - so your return lined needs to go to the rubber line that the stock (oem) fpr was connected to (#3 in ur pic)
:)
 
#8 ·
And if I remember right the line coming from the passenger tank hooks up to #1
 
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#9 ·


1. Connects to a rubber line that's in the tank already, leave that alone.

2. Connects to nothing, leave that alone.

3. Snip the black line, close off the end of the stock FPR. The return line should come through the hole near the Walbro pig tail then connect to where the stock FPR was connected to.
 
#68 ·
I know this is an old post but I was reading it and was a little confuse of one part of it, one guy say not to do it this way cause the return gas will go to the other tank and not the main while others say to do it the way it was posted. I just want to make sure I'm doing this the right way so if anyone knows how to please help.
 
#10 ·
sounds good, thanks again folks.
 
#11 ·
I assume all of you who have done it this way don't have problems with getting fuel from the other side of the tank? TE's setup requires a few more tweaks (drilling out jet valve larger, and flipping the nozzle contraption that you guys are talking about) but it obviously didn't work well that way.
 
#12 ·
TeCKis300 said:
I assume all of you who have done it this way don't have problems with getting fuel from the other side of the tank? TE's setup requires a few more tweaks (drilling out jet valve larger, and flipping the nozzle contraption that you guys are talking about) but it obviously didn't work well that way.
I didn't drill the hole bigger, I don't believe I have any problems with getting fuel from the other side of the tank. I can look again later on during the spring.
 
#14 ·
thanks again guys, got it all figured out. +repped everyone who lended a hand and info :)
 
#16 · (Edited)
Malekreza11 said:
dont drill te hole, and dont flip no nozzle.
doh!! TE's instruction said to use a .94mm bit to make the hole in the jet valve bigger. Their picture also showed that the jet valve is flipped around....

Attaching original TE instruction image:
 

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#17 ·
NaFooEsi said:
doh!! TE's instruction said to use a .94mm bit to make the hole in the jet valve bigger. Their picture also showed that the jet valve is flipped around....

Attaching original TE instruction image:

yea, dont do what the instruction manual says... Dont drill the Jet valve too large and dont flip the Jet valve nozzle either.
 
#18 ·
Malekreza11 said:
yea, dont do what the instruction manual says... Dont drill the Jet valve too large and dont flip the Jet valve nozzle either.

Wish we knew that beforehand! LOL. You figure...there are instructions and you would want to follow them right? Wonder if these instructions were from the great IS300GTE's legacy where he proclaimed omipotent understanding of all things cars.

The way that you guys have done it seem easy and straight forward...it literally would work the exact same way as stock when done as such. Wonder why TE/IS300GTE thought they needed to mod it further?
 
#19 · (Edited)
As I'm currently doing this project ....
I am plugging up the stock FPR shown in pic above as #3.... nevermind 'm trying to reinvent the wheel. just follow above instructions
 
#20 ·
TeCKis300 said:
Wish we knew that beforehand! LOL. You figure...there are instructions and you would want to follow them right? Wonder if these instructions were from the great IS300GTE's legacy where he proclaimed omipotent understanding of all things cars.

The way that you guys have done it seem easy and straight forward...it literally would work the exact same way as stock when done as such. Wonder why TE/IS300GTE thought they needed to mod it further?
I don't believe either one of these effects pulling fuel from the other side of the hump.

Drilling out the Jet valve allows your fuel sensor to read alittle more accurately.

Moving it simply moves it.
 
#21 ·
lambchop11078 said:
Here's what you need to do to the fuel pump assembly.

1. Drill a hole in the plastic fuel pump assembly.
2. Get a bulk head fitting and install the fitting on that new hole.
3. Install the return line from the FPR to the end of the fitting that's exposed.
4. The other end of the fitting that will be in the tank needs to connect to the white ventricle.
5. Cut the line that's connected between the stock FPR and white ventricle.
6. Either pinch the nipple that is now exposed on the stock FPR closed and weld it shut or get 1/4" fuel line, 1/4" bolt that has no threads on the shoulder. Cut off the threated area of the bolt, insert the bolt in the 1/4" line and put a hose clamp on it. Put the other end of the rubber line on the stock FPR.
6. Run rubber line from the bulkhead fitting to the end of the white ventricle that the stock FPR was connected to.
Question??????
WHY ?
I did steps 1-3and 5, I JB welded the Fuel Pressure Regulator shut. and also shut where the FPR use to plug into. What I don't know or understand is why do I need (step 4,6 )to conneect from the fitting to the white ventricle. why can't I let it just freepour into the tank. from whta I see by blowing and sucking into the white ventricle it just re-routes but does nothing more. Am I missing something very important? I have driven the car maybe 50 miles and it doesn't act up. is it building pressure or something to do with the passenger tank that I don't realize?
 
#22 ·
You need to have the return fuel flow through the contraption because it is the mechanism that will draw fuel from the other side of the tank. It works based on Bernoulli's Principle. The return flow of fuel essentially creates a low pressure region within the contraption which will draw fuel from the other side of the tank. Without this, you car will still work fine. You will just loose about 4 usable gallons that you can't draw from the other side.
 
#23 ·
SophieSleeps said:
I don't believe either one of these effects pulling fuel from the other side of the hump.

Drilling out the Jet valve allows your fuel sensor to read alittle more accurately.

Moving it simply moves it.
Drilling out the Jet valve has nothing to do with the fuel reading!

I think the rumors of non-working fuel gauges has to do with the early pioneers that didn't know how to use the fuel draw contraption which meant they couldn't get access to the last 4 gallons of fuel. This lead them to think the fuel gauge didn't work. If you set it up right as shown in this thread...you should most definitely have a working fuel gauge.

There has also been rumors of the stock ECU calculating fuel level from MAF/injector duty cycle. While I believe the ECU does use it to some extent, as an engineer...this is counter intuitive. You would never derive a reading when there is an actually float that can give you the true value.

So change the injectors/standalone/tuning all you want. Get the jet valve contraption right and you will have a working fuel gauge!!!
 
#24 ·
NaFooEsi said:
doh!! TE's instruction said to use a .94mm bit to make the hole in the jet valve bigger. Their picture also showed that the jet valve is flipped around....

Attaching original TE instruction image:
Jason,

I don't remember exactly how u put this together...but I think you have the draw line on the wrong fitting. Is your draw line on the middle jet valve fitting? It needs to be on the other short one. If it is...the return fuel is going straight to the other side of the tank.

Also, put the thingy back in the stock orientation. If the jet valve is not above the "cup thing" underneath it catching the return flow, the jet valve will be aerating the fuel in the tank which you don't want.
 
#25 ·
Drilling out the jet valve would probably be beneficial to you guys that are running much higher flow rates as the stock small orifice would be limiting the return flow rate, building pressure in the contraption and nullfying Bernoulli's Principle.
 
#26 ·
TeCKis300 said:
There has also been rumors of the stock ECU calculating fuel level from MAF/injector duty cycle. While I believe the ECU does use it to some extent, as an engineer...this is counter intuitive. You would never derive a reading when there is an actually float that can give you the true value.

Counterintuitivity aside, did you see my testing that resulting in me saying the MAF reading is very important?

1) MAF completely unplugged. Car/tranny in limp mode, gas gauge drops by 1/4 tank increments regardless of the float gauge

2) MAF plugged in, but wrapped in a rag in engine bay (not in air intake stream, just hanging). No limp mode, but gas gauge still drops by 1/4 tank increments. No love from float gauge.

3) MAF plugged in and installed in air intake. Dead on accurate gas gauge.


Unless the car was throwing a code for MAF voltage out of range, which for some reason bypasses the float gauge and disables the gas gauge, the MAF has some important function here... but it's not the most important thing.

I think you're probably right with the saddle tank thing and it's effects on early gas gauges.
 
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