98 TRD 3.4L Turbo , Methanol , LT

^ This. What are the symptoms? Sounds like the tuner can't admit his mistake and is blaming your truck...

 

Buying a denso pump today. I think it was the pump, because before the truck died, the afr's were ALL OVER the place, mostly pulsing up super lean into 18-20 range, hesitations, even just getting it to idle was crazy. Id have to floor it to even barely do anything. The local rock radio station here is at the tuner shop today and they are doing cheap dyno runs. Wish I was up and running.

I forgot where the stock fpr was ran from.... There would be two points I'd have to rerout.....from the plenum and the one just under it. Anybody have a pic? I'm going to look back at my pics too.

Edit : I think the plenum tube was just capped off. And the fpr reference was off the intake pipe

 

Did you test fuel pressure at the rail?

 

Not that I know of. He tested voltage at the pump and it wasn't turning on at all.

Where would I route the fpr now, because the intake now has pressure? This was stock, off my cold air intake. Now with boost, should the line go pre turbo or still on a charge pipe?

 

Voltage at the pump imo would be another issue than a bad pump. Check fuses, relays for the pump?

 

Yeah thanks, when I stop by there I will ask too.

 

Well you should have some vac lines that don't currently see pressure, like the one that goes to the right backside of the intake manifold. You can tee it onto that one or simply hook up one of those tiny 3/8" air filters straight to the nipple of the FPR just to the right of the throttle blade. It may be fine how you have it, but I wouldn't chance it... those FPRs aren't cheap

 

I disagree with Gio. Your FPR should be connected to your charge pipe. As boost increases, the FPR will open more allowing proper fuel pressure. Could be the issue

 

Is that is where you are running yours?

 

Yes. I have mine connected right behind the TB where the PCV valve used to plug into.

 

Do what you want, but the FPR wasn't meant to see boost... not even from the SC straight out of the dealership. The bigger pump supplies the needed fuel pressure and bigger injectors use that added fuel pressure. Like I've stated before, the only reason that it would be needed to put that extra force on the FPR is to increase fuel pressure under stock fueling conditions.
You are literally pushing 9 psi on a fragile diaphragm that was made to see atmospheric pressure only. Once I tune my truck at 8 psi, that hose is comin off my manifold

 

Yea pretty sure my supras was pre turbo

Although..idk how cars would do it with no pre turbo pipe..

 

So pre turbo then.....? That's what I was thinking because stock it just sees airflow before the maf. And with the piggyback you can control the fuel pump all you want.

 

Bought this denso 950-0159 yesterday. Stats say it's good for 280lph. Hopefully reliable too. Came with filter and all off Amazon.com (listed at $346, paid $140).



Plan now is to get that pump in, rerout the fpr hose pre turbo, and dyno tune. Damn, I want this thing back so I can start ripping off my front suspension for LT!

 

I'm pretty sure your fuel pressure regulator needs to be connected to your charge pipe. If you have a filter on it, its not seeing any idle/vacuum or boost and can't dynamically adjust fuel pressure based off of engine needs. Doesn't mater how big your pump is, its just pumping in circles if the FPR isn't working correctly.

 

Ok, I have a nipple on my charge pipes too. I really need to get this right know what I mean. I can't afford the time away from getting groceries when I want, haha. Or throwing money at the tuner.

 

Being that your truck was N/A from the factory, having no boost or vacuum source on the FPR should leave it at ~43.5 psi fuel pressure.

If you add a vacuum hose post throttle body, then the FPR will see vacuum and boost. This is how most F/I aftermarket FPR's are setup. This would be the rising FPR setup.

Being that you have larger injectors and pump, you might not be interested in increasing the fuel pressure. Being that your tiny OEM FPR wasn't designed for boost, it can easily be overwhelmed.

I suggest capping the FPR for the time being, to help ease the tuning process. Until you upgrade the FPR to a larger diaphragm one. Then be sure to tell your tuner that you have that hooked up because it will add a lot more fuel under boost. The tune would then need to be adjusted.

 

From the factory the fpr was routed to the intake pipe (cia). It saw minimal pressure, just air flow that the intake sucked in. I'm at a loss now only because I have 3 people telling me 3 different things. It's all good, I want the best solution. Maybe have to have the tuner decide....? I feel all the info you guys are providing is valid.

I also have one of these laying around. Would this help the situation any? Adjustable to 140psi.....



I think it was @Blackdawg that mentioned the fpr doesn't need upgraded as its similar to the supras.

 

That is the same way the OEM vacuum routing is for the 2nd gen.