j-tube advantage?
- Thread starter purepontiacgto@
- Start date
yes, its a fail safe if your FPR gives out on you. If you're stock keep it, you have no good reason to lose it
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.
It's more than possible that some people have had the stock FPR fail on them, but didn't notice, because the J tube takes the job.
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.
Interesting. So the most common failure is diaphragm rupture, and the J-tube may actually make things worse (richer)!
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.
Yeah, but the dribble from the injectors is compensated by the firehose of fuel being sucked through the diaphragm and into the vacuum tubing.
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!
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...
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...
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