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Discussion Starter #1
I just got my return fuel system finished up and am having an issue with setting fuel pressure. I ran a Walbro 525 pump with an 8an feed and 6 an return. FuelLab regulator on the return, with a Radium Engineering gauge. All parts high quality. I can't get the gauge to read past 20psi. The car starts and runs, but the gauge stays at zero key on engine off, but goes to 20 psi running, and doesn't respond to spinning the pressure setting screw in. The car revs up and seems to be ding fine, still shows 20psi. But I don't know what is going on with the fuel system, so way to worried to drive the car.

No fuel leaks, checked all fittings. If it matters I'll name off all components in the system.

Starting with the pump in the modified factory hanger, 8an feed line goes to a Radium in line filter, then to the 8an rail with (currently 550cc injectors), 6an out to the regulator, then 6an back to the hanger.

Id like to know what the gauge should read just keying the car up, then running at idle, then what to set it too.. I should have the vacuum line disconnected to set base pressure correct?
 

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Is there any possibility that the fuel line running directly off the pump split?

That could theoretically cause the pressure to be low
 

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Discussion Starter #3
I'll have to pull the hanger back out and look, I used in tank specific flex hose and not only do you literally have to heat the ends to install over the ports for an extreme tight fit, but I also clamped them. So highly unlikely. But definitely a good suggestion, thanks.
 

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Discussion Starter #4
I checked the hanger and everything I did there. I disconnected the line before the regulator and have fuel flow for sure when cranking. Gushing flow. So I have to look into whats happening at the regulator. I'll mess with my routing etc. next. The car sat with an open tank for a long period of time while the engine was out and the hanger out for mods. I suspected bad gas, so drained the 1/4 tank and put in 5 gallons of fresh fuel. This allows the car to start sort of, but still only 20 PSI pressure and no change with adjustments. Doesn't run good enough to drive and my wideband o2 gauge says its way too lean of course. There is one port unused on my regulator that I have capped off, I already have my lines cut and can't try it, so I have an adapter on the way so I can try my return line from this port and cap the one I have it hooked to. Hope that will fix my issue. Will update when the fitting comes and is installed.
 

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Discussion Starter #5
Good news is I just had the regulator plumbed wrong. Got an elbow -6an fitting to hook my return line off the bottom where it goes, now I have full adjustability of fuel pressure and easier starts etc. However the odd thing is that the car is running very rich anywhere close to factory fuel pressure (according to my AEM UEGO wideband/ A/F gauge). I can adjust pressure down to about 25psi to get closer to 12:1 when accelerating. Why does my pressure have to be so low to run right? Factory pressure is 43.5 with vacuum disconnected and what the car was tuned on before my rebuild. But that pressure makes the car so rich it just bogs and blows black smoke when trying to accelerate.

I really want to drive the car a bit and break in my new engine, trans, and diff rebuild before going straight in for dyno tuning. But it's not running right because the fuel pressure and going too rich under acceleration. And I don't want to take the pressure down even lower.. how can that be right? Any ideas?
 

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I see your running 550 injectors. what ecu is the car running ---meaning what injector size is it expecting (are you oversize)

next, if you spent some time idling at 20psi pressure the cars computer (making assumptions here its oem ecu) started doing its correction (saw it was lean) and started adding fuel via the fuel trims. resetting the ecu (efi fuse or battery disco) will take out these learned values ...if that is part of the problem

but if you oem ecu is expecting 440, 340's (were in the na section here) you will prob have to run very low pressure without some sort of piggy back
 

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Discussion Starter #7
It is stand alone tuned for the 550's. AEM Infinity ECU. It should be happy at OEM fuel pressure because it was tuned on the stock system. But for some reason I'm having to run way less pressure to keep A/F ratio decent. Like 20 psi. Don't get it. It is a Fuelab regulator, Radium gauge, and TI 525 pump. All good quality stuff. I don't think I'm seeing miss information on the gauge.
 

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Discussion Starter #8
As mentioned in my other thread, my wastegate took a $hit. Would this have anything to do with my fuel issue? Maybe it's going too rich because the turbo isn't pushing any boost? And the ECU thinks it is? Something like that?

I'll definitely be messing with with the fuel pressure again after I fix the wastegate issue. Hoping to see better readings at factory fuel pressure with the wastegate replaced and working.
 

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Hey man, I seem to be bird dogging all your threads haha. I wouldn’t think that your broken wastegate would cause your overly rich issue. I would advise setting fuel psi to stockish, opening up Infinity tuner and looking at your VE map under idle. I think that your tune needs touched up. Since your rebuild, the engine now has different requirements for fuel/air. You changed pistons, and cams, and I’m not certain but possibly injectors too between the stock GE and the built GE. I know it doesn’t seem like much, but those are huge changes to the how the engine will breathe. I also would recommend getting a fuel pressure sensor wired up to the Infinity like https://www.aemelectronics.com/products/sensors-connectors-accessories/map-pressure-sensors It will help calculate fueling needs and fuel pressure failsafes. Cheap insurance and who doesn’t love more data?
 

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Discussion Starter #10
I appreciate the help. I'll look into the fuel pressure sensor. But really the only change is the dished pistons. I still have the 550's it was tuned on before the engine blew installed. I had the 264 cams at that time too. So only the compression drop to 9:1 is different. I'm sure it needs tuning, but I did't expect to see this far off. All I'm trying to do is get 100 or more miles on my new engine, trans, and diff, re-check everything, and take it in for tuning. I don't trust just throwing an unbroken in engine on the dyno. After my re-check, it's getting the 1200cc's installed, another oil change, and the associated boost control stuff. But right now, without a working wastegate, the thing is hardly driveable because it's totally dependent on the turbo now and there's just no boost.
 

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I hear ya man. I’d almost bet it’s the change in CR. When I went from stock cams to GSC S1 cams it would hardly idle without keeping the throttle lightly pressed. I was really surprised how much difference one change can make.
 

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Discussion Starter #12
Does anyone know if the new Walbro (Ti) 525lph pumps are dimensionally the same as the 400, 450, 485, etc? I am looking into PHR's dual/tripple pump hanger from Suprastore. They offer it with 1, 2, or 3 485's, but I already have a 525, and would like to run 2 together for my fuel needs. But if the pumps are even slightly different, I don't wan to mess with fitment issues. Like the 525 sitting slightly too deep, or shallow etc. If so, I'll obviously be fine with 2 485's. Just would rather buy 1 more 525 than 2 485s to save money.

I am concerned with my fuel needs even with the 525lph because it is rated about exactly for my power goal, but I don't want to have just barely enough fuel. I want to be overly sufficient. The 525 supports 1000hp N/A but says around 800 for turbo applications. 800 happens to be my power goal.
 

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Check this out. You’d think Ti (Walbro) would have this info posted, and maybe they do and I just missed it. Anyway, some good info from Radium and I’d trust them on it. 👍🏼
 

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Discussion Starter #14
Seems like they've really been perfecting these things. Many models that just keep getting better. That was a good read for me as I now realize I have the F90000285 which is still considered a 525lph pump...? But it says flows 470lph at 40psi..

The F90000295 is a 525lph pump that flows 525lph at 40psi (due to there being no check valve). Even so, the 295 version is still ratted for 900hp N/A and somewhere in the 700-800hp range for FI. So now I feel like my 285 is very likely not sufficient for what I'm doing. At this point replacing for a 295 would still be foolish. I should probably just buy the 485's that PHR sells with the hanger (because they are cheaper) and run them in stage. The time and money just keeps going with this thing now :rolleyes:. But I'd have way more than enough fuel and would't have to worry anymore.
 

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The time and money just keeps going with this thing now
Word!
I’d rather over do it, than do it over. I have the two AEM E85 (50-1200? Maybe) pumps in a staged config, second pump comes on at like 10psi of boost.

This Is a couple years old but still relevant and a good read as well.

I’m using an billet Full Blown Motorsports Evo VIII dual hanger in my IS, it would probs fit your GS too. I had to have the top flange machined down to fit the fuel tank opening. I waited for the Squash Performance hanger to get restocked but I think the demand is too low. There’s also Autosports Engineering...I bought his coil pack brackets to run 1NZ coils. Brackets are great but dude couldn’t send me the three different brackets (each bracket is unique on the VVTi) to save his life. I think he thought I was scamming him for extra parts, IDK but I made it work. Can’t recommend ASE for that reason though. The PHR hanger is probs gonna be the best bet for drop in, ease of use, and functionality.
 

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Discussion Starter #16
According to that RealStreet test a single 525lph is sufficient for my goals.. At least at the pressures I'd be seeing. I appreciate the info you're sharing. Now I'm torn on if I should go dual pumps or just keep what I have.
 
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