j-tube advantage?

GrimJack

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Dec 31, 1969
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Keep in mind that if your FPR goes out on you and you're driving on just the J-tube to build fuel pressure, you're in severe limp mode, as in, do NOT go into boost, and get to a shop as soon as possible.
 

GrimJack

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Dec 31, 1969
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Oh yes, we've seen a few of them go. It's really annoying, because when they go, the vacuum in the intake manifold sucks fuel from the fuel rail into the intake manifold through the vacuum line. It's not nicely sprayed in there like the CSI, either, it's like pouring fuel in from a gas can. Engines tend to run like total shit, if they run at all.
 

zurud

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Apr 10, 2005
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No. without the j-tube, and your fpr broke, you wouldn't build any pressure in the fuel system to run your car. Your injectors will dribble the gas instead of misting it.
 

7MGTEsup

Formerly 'Down but not out'
Jun 14, 2005
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I would think it near impossible for the spring part of the regulator to fail, so diaphragm failure is about the only thing to go wrong.
 

GrimJack

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LOL - actually, the vacuum hose to the FPR isn't *that* big. Plus, liquid fuel doesn't burn well. Last time I helped with one of these, the first two cylinders were basically not firing, car was running on the back 4 only. We were pretty sure the head gasket had popped and coolant was preventing the first two from firing... imagine our surprise when we pulled off the head and the gasket was fine!
 

jetjock

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Jul 11, 2005
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Redacted per Title 18 USC Section 798
I've seen only one fail and it was in the manner Grim said. In that case the leak was small and the engine exhibited no symptoms. The leak was found only because I make checking them a habit. I use a hand pump for that by pulling a vacuum and watching for leakdown. A loss of rest pressure would be another indication but that can be caused by several things.

I'm assuming in theory Toyota sized the tube's orifice to somewhat allow the feedback system to compensate for an FPR leak but as Dan's sig so succinctly points out...;)
 

suprahabsfan

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Sep 28, 2007
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You HAVE to drill out/bypass/eliminate the J-tube if running a walbro fuel pump, or upgraded fuel system. The small hole will cause too much backpressure and your car will run rich. So there is no real gain, but is a necessity when upgrading your fuel system. If worried about stock FPR, buy an aeromotive FPR