quick Jtub Mod ????

[noel]

i did some research on this subject i just wanted to make sure im correct before i proceed with this j-tub mod

I do have a walbro 255 fuel pump but everything else about the fuel system is oem Now the question by doing the jtub mod is it safe to go thru with it even tho i dont have aftermarket injectors/regulators?? if it matters i do have others mods like ic/pipes/exhuast/intake

 

[Turbo Habanero]

I was under the impression that the mod was done mostly when people do a AFPR

 

[JStoked]

Ya I think the stock fpr will hold it. But with out any other mods it's a waste of money. Unless you got one cheap like I did. Just make sure if you do it to check you fpr and make sure it's not leaking.

 

[Turbo Habanero]

The AFPR kit gets rid of the pulsation damper along with the Jtube.

Here is a guide on all it below

http://www.supramania.com/forums/showthread.php?97699-Guide-Installing-Lexus-AFM-550s-and-AFPR

 

[noel]

Dammit so I need the afpr in order to do the jtube mod?? That sucks

 

[Turbo Habanero]

Dammit so I need the afpr in order to do the jtube mod?? That sucks

I'm not sure you need a AFPR i just think it's more along the point of the Mod being pointless until you start upgrading your fuel system more and then you will need a AFPR

 

[JStoked]

Yep it is point less till you can afford to upgrades your fuel system.

 

[hvyman]

No no.

The j tube mod is done when you put in an aftermarket high flow fuel pump. The j tube acts as a back up fpr invade the actual fpr fails. It will build too much pressure when you add a bigger pump.

Change the pump and do the j tube mod or just bypass it. You don't need a afpr to do the mod.

 

[Turbo Habanero]

No no.

The j tube mod is done when you put in an aftermarket high flow fuel pump. The j tube acts as a back up fpr invade the actual fpr fails. It will build too much pressure when you add a bigger pump.

Change the pump and do the j tube mod or just bypass it. You don't need a afpr to do the mod.

Oh.. hmm I've been running a walbro with the jtube for about 6months lol. Guess its time to bypass it oops.

Sorry for feeding the OP wrong info.

 

[harley1985]

did you do the 12v mod? ive heard its necessary, and then its not. also, (call me stupid) but what is the jtube mod? from what i understand all you do is widen the tube rite? so why not bypass it? im going afpr and thats what i plan on doing. they even have a block off plate u can buy.

 

[Turbo Habanero]

did you do the 12v mod? ive heard its necessary, and then its not. also, (call me stupid) but what is the jtube mod? from what i understand all you do is widen the tube rite? so why not bypass it? im going afpr and thats what i plan on doing. they even have a block off plate u can buy.

I think bypassing it is the mod. And I've seen the block off plate before too but I'm not sure you need it the link I posted above mentions nothing about it

 

[Nick M]

The mod is to drill out the restriction. Bypassing it is to remove the tube all together. Or leave it and look tacky while looping the lines together. The 12V mod eliminates low speed fuel pump operation. Low speed is for when there is very little demand for fuel. Such as not in boost. When tuning a modified car, it causes a headache. So the low speed portion is eliminated altogether.

 

[harley1985]

gotcha, im going to just bypass it. saw the line on DM for like 65 bucks. kinda high if u ask me, but wat the hell. as for the 12v mod, will that hurt your MPG?

 

[noel]

im Boosting 13psi with this {jtub restriction} i do have the walbro 255 pump. so by doing this mod it just relieves pressure and lets fuel flow more freely?? im pretty sure i dont need the 12v fuel pump mod since im not near tuning yet. and harley1985 asked a good question does that 12vmod mess up MPG???

 

[supraguy@aol]

Shouldn't really affect mpg terribly, as most of your driving is in closed loop O2 operation.
This means that regardless of the psi at the rail(within reason), the injector duty time will be adjusted
to keep O2 readings in a normal range. Wide open throttle is where a higher fuel pressure(due to AFPR, Walbro or 12v mod) would cause a richer mixture. Thing is- the majority of WOT time is spent with the fuel voltage switched to
12v operation anyway.