J-Tube

[91Supra313]

This may sound like a Noob question, but, how in the world do you bypass the J-Tube? I have heard so much about this and since my fuel tank is out and waiting on a new bracket to come in, I figure I might as well do this mod too. If someone can show me how to do this I would greatly appreciate it. Also, what does this mod do for the fuel system?

 

[Koenigturbo]

How I understand it ( I got this info from the reading threads here) this mod is usually done because we upgraded the fuel pump. From reading threads here the J tube has a resriction. You can drill it out. What I did was I completly by passed it. By drilling it, I would be afraid that there would be metal shaving left over from drilling it, how ever, I guess you could blow it out with a compressor.

From what I know the J tube keeps the gas from draining back to the tank, so next time you start your car it won't take for ever to start. I could be wrong on this, but then again I may be totally wrong on the whole reply.

 

[NTRA08]

How I understand it ( I got this info from the reading threads here) this mod is usually done because we upgraded the fuel pump. From reading threads here the J tube has a resriction. You can drill it out. What I did was I completly by passed it. By drilling it, I would be afraid that there would be metal shaving left over from drilling it, how ever, I guess you could blow it out with a compressor.

From what I know the J tube keeps the gas from draining back to the tank, so next time you start your car it won't take for ever to start. I could be wrong on this, but then again I may be totally wrong on the whole reply.

That makes alot of sense. My car was hard to start in the morning and I did away with the j-tube also.

 

[Sawbladz]

There is a more important function to the J-tube. If you were out driving and your fuel pressure regulator went out, the J-tube manually restricts flow and keeps enough fuel in the rail to allow the car to limp home. When upgrading to a higher displacement pump, this tube should be drilled or bypassed and you should run it in conjunction with a AFPR. Do not drill the J-tube on the car. It comes off the engine block with 2 bolts.

 

[Koenigturbo]

The N/A block has a plate that you can bolt right in it's place if you decide to completely by pass it, or a small block Chevy fuel pump plate will work.

 

[stolensupra]

I got my plate from amazon for like 3 dollars

 

[91Supra313]

Ok so once the plate is on, where the hell do I reroute the fuel? I am a true retard when it comes to things like this. You all should have seen the hassle I went through with the whole EGR block off stuff.....lol. I just don't want to get anything wrong on this and blow my car up.....not like that would be a first for me.

 

[JDMMA70]

While on the subject of J-Tubes. Is the torque specs to bolt it on correct? 89ft lbs? seems a little high

http://cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=EM&P=94

 

[stolensupra]

This is a great article. Just ignore the instructions on how to install LEX AFM and 550's. Although there is no real reason other than engine bay dress up (that you can hardly see) to block off the j tube without at least installing an adjustable AFPR for the future hope of Lex afm, 550's and upgraded fuel pump.

http://mkiiisupra.net/bbs/showthread.php?t=13885&highlight=guide+controller

 

[OneJArpus]

While on the subject of J-Tubes. Is the torque specs to bolt it on correct? 89ft lbs? seems a little high

http://cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=EM&P=94

Yes. too bad the HG bolts weren't that high or we'd never have problems with it LOL

 

[91Supra313]

yeah see I have a Lexus AFM, Upgraded pump, and 550s. So would it even be worth the time and effort to block off the J tube thingy?

 

[Koenigturbo]

no, but from what I read here if you have the Lexus/550 you should also, get a A.F.P.R. ( According to S.M.)

 

[91Supra313]

That will end up waiting until the car gets back to the US in a few years. There is no point in spending that much cash on something that will be sitting in storage for 2+ years, waiting to be shipped.