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Discussion Starter #1
i have seen some people have done this mod. whats the deal with it idling different after the mod? Is this cause tyhe engine is running richer? give me any insight thanks Brett





www.mkiv.com/tmp/bd_fuel_bypass_line
 

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I really couldn't tell a difference.

Later, Steve
 

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Anyone know the fittings sizes?

What are the sizes used on the various fittings? I'm familiar with working with AN hose and fittings but don't know what sizes the fuel filter and rail adapter use. This looks like one of the first places to look in order to get better fuel flow, adding a fuel pressure gauge is a nice benny too :)
 

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The size of the rail and filter are 12mm x 1.25. You can get this with a -6 on the other end (12mm x1.25 Dellorto / Solex / Mikuni). You can get these for $5.16 at www.amstreetrod.com Then you need a -6 90 hose end and either a straight or 45 degree hose end at the filter. $23 or so if you get a straight end coming off the filter. And about $18 for 3 ft of -6 hose. Measure the length you need before you order. Under $55 total. PHR sells the metric fitting for $15 and everything assembled for $95 I think.
 

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Thank you!

I looked all over for that information and couldn't find it, thank you! A local guy too :D I found a shop selling the adapter parts but no measurements and I found a "kit" to do it too. I understand that some folks are looking to make a buck but geez this isn't rocket science! Those of us who can cut line and are comfortable with AN fittings aren't going to be willing to buy what we can make for much less.

Hrm, now anyone know who makes an EL fuel pressure gauge that doesn't measure in Bar? Converting for boost is bad enough but I'll go crosseyed trying to do it for fuel pressure too :)

P.S. that place has some killer parts for sale - lot's of oddball stuff! Thanks twice - can use this for a few other projects too :D
 

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BLKMGK,

What's the name of the shop? I've been ordering from summit and jegs but it would be nice if there was some place local I could go to.
 

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No...

I meant YOU'RE local. The shop I ordered the fittings from is the one you mentioned. I checked prices between them and Jegs and found several that were lower by a couple of bucks. Shipping is additional but they don't charge the handling fee that Jegs and Summit do so it worked out. No store local sells aluminum AN fittings except C&C and another shop that specializes in circle track stuff - they don't beat mail-order and C&C barely stocks anything :( There's supposedly a hydraulic shop around in Manassas that has steel fittings and I've gotten some weird ones from NAPA but I prefer the lighter aluminum ones :)

I don't recall which store it was selling the adapters without the measurements but it was one of the stores that specialize in Supras. I think the pieces were like $12 apiece so your source was still cheaper. I ended up ordering the two adapters and a fuel pressure adapter from them. I believe I've got plenty of -6 in the garage and probably have the other fittings too. :) Only thing I might need is a -6 male\male adapter for the fuel pressure piece (shrug). I'm not in a hurry, this will probably be my first fuel mod and I'm on stock boost for now...
 

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Cool, I'm clear now. I've got a complete parts list on my web site on upgrading the fuel and where I bought the parts from. I bounced back and forth between jegs, summit and amstreed rod depending on the prices.

Hard part will be at the fuel rail. The egr stuff is in the way and it's up against the firewall. I think some people just disconnect the stock line and move it over since the hard stock line runs through the intake manifold and leave the pulsation dampener in place. If you want to get it out, go from the bottom with 3 and 6 inch extentions and a breaker bar. 3 for the bottom bolt and 6 for the upper. And you will have to probably take off the upper intake manifold to get the hard line out.
 

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Discussion Starter #11
what do i need excatly do buy from a speed shop like s-k speed to do this mod? What size fuel line and what fitting. -6 -8? Does the tt have bigger fuel lines then a n/a supra? I want to do this mod to my car and dont want to pay 85-95 from some guy for the parts. whni can o it chepaer and just the same and i dont have to wait for parts. ya knw anyways post if you have ogotten one of these kits or made one and what it actually conssists of. Thanks Xdreamer.. also how do you take you airbags out? Do i just have to discoonnect the abteery and i can ? LEt me know Thanks guys
 

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I've actually looked over your WEB site a bit and couldn't find that listing :( I did more than a few searches on the 'net trying to find the information too and came up dry. Glad to hear someone has documented this. I will probably do the same on my site when I get to that point. I've only just today gotten my car and want to get used to it before doing anything at all to it. Kripes, this sucker hauls butt!

Oh, and I appreciate the advice on the stock line. I hadn't thought about how hard it might be to remove. Leaving it in place, so long as it doesn't rattle, will probably be my solution. Some of the pics I've seen showing the location on the back of the rail make it pretty apparent how tight that is, I think it'll be warmer weather before I go crazy trying to get in that little spot :)
 

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On my site, click on fuel system. The next page has a diagram and a bunch of docs on various fuel system installation topics. One of the docs is called fuel sys parts. That is a complete list to upgrade the whole system.


Xdreamer:
To make the bypass you need:

12mm x 1.25mm by -6 male adapter
-6 straight or 45 degree hose end (filter side)
-6 line
-6 90 hose end (rail side)
12mm x 1.25mm by -6 male adapter

I've never measured the length but somewhere around 3 ft or less I would guess.
 

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Discussion Starter #14
I apreciate it . im going to get these prt's this week and do it.

Will doing this give me more fuel at idle and wot? Cause theres less resticiton meaning more flow. and the computer is set up with having the restriction fuel damper in mind. Does tha sound right. Any one have isdea's on this now i know what i need.

I have added like 20-percent more air into the intake manfiold by removing a big restriction and taking out my egr/ so im hoping this will fix the problem with low idle. cause i have to much air and not enough fuel at idle. I am changin the fuel filter as well when i do the bypass. Thanks Brett
 

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Nope...

Fuel pressure regulator is what regulates the amount of fuel pressure you have. Changing these pieces will result in a system that has the SAME fuel pressure - idle shouldn't change nor should the amount of fuel being pumped into the engine. So why do it?

At a certain point your injectors will be firing at a pretty high duty rate to keep up with the air flowing into the engine. At that point the VOLUME of fuel being used will be HIGH. IF the fuel line feeding the fuel rail\regulator cannot keep up fuel pressure will begin to fall and a lean condition will result. That's a BAD thing (tm). Removing restrictions between the fuel rail and fuel pump allows a greater volume of fuel to flow under WOT conditions. Adding a second pump or larger pump will also increase the volume available should your injectors flow more than the OEM pump can deliver. Make sense?

You said that you removed a restriction in the intake and that this changed your idle speed? That doesn't make sense, it should still idle pretty close to the same as it's the IAC valve and throttle plate that limit idle - not any restriction in the intake tract leading to the throttle body. Unless the thing was struggling just to get enough air to idle modifying anything forward of the throttle blades shoudln't change idle - but will change WOT response if there was a restriction. BTW - put a sensitive vac gauge on the side in front of the turbos or in front of the throttle blades on a NA car and go for a WOT blast. If you see vac there's a restriction...

What EXACTLY did you do and are you sure that the change is what resulted in your low idle? NA or turbo?
 

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Discussion Starter #16
ITS A N/A AND I WILL TRY THAT .DOES ANYONE ONE KNOW WHAT THE ELECTRIC MOTOR SOUND THATS UNDER THE HOOD? mY CAR WHEN IDLING AND IN PARK I CAN HER A ELTRCI MOTOR RUNNING . MY HEAT AND EVRYTHING ARE OFF. DOES THE SUPRA HAVE A POLLUTION PUMP THAT HEATS THE CATS UP ON A COLD START . MY IMPALA HAD THIS AND THATS WHATS THE ELECTRIC MOTOR NOISE WAS. THANKS


ALSO CAN THE STOCK FUEL PRESSURE REGULATOR BE ADJUSTED OF SHOULDI PICK UP A AFTERMARKET ONE. ? i HAVE A AIR/FUEL METERE THATS IN GOING TO INSTALL TO MAKE SURE EVERYTHINGS RIGHT. tHANKS
 
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