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I have a 340LPH pump in a 99+ fuel tank. I've tried three different C5 FPRs of different makes and none offer a perfect pressure solution. I already bought a Fuelab 51502-1 as recommended on the HPTuners forum and plan to mount it in the engine bay for ease of access. But maybe I could safely set-it-and-forget-it before the engine bay if it can still be protected from damage. I'd prefer to not mount it directly to my OEM LS3 fuel rail in case I decide to install the XS LS3 intake down the road... no need to reinvent the wheel. I have the parts to mount it directly to the rail for now if needed, but I'd prefer to know how else to optimally mount it.
Regarding the inline filter, how to swap from the C5 to a different inline filter and which to select and where to mount. I have a new OEM fuel filter to go in there, but the fittings were changed to use the C5 FPR. I've read that the OEM fuel filters are ~17micron, and Fuelab offers inline filters with & without a check valve (don't know the purpose of the valve) and the 51502 mentions "Fuel Filter with 60 Micron or Lower Particle Rating is Required. Fuelab Filter with 6, 10 or 40 Micron Rating is Recommended." I need it to be reliable and try to keep it simple. What combination of location and inline filter should I pursue?
From: Halfway back on the Highway to Hell...again!
I just replied in another thread a few min ago. The C5 filters suck with bigger pumps.
What fittings are currently on your lines that you have adapting to the c5 FFR? anything is easily adaptable nowadays.
See photos of current fpr connections below. Easy to roll back to the OEM fittings to use the oem style inline filter? Or better to change fittings to connect to an inline aftermarket filter?
C5 fpr installed, currently using Wix 33100. Same design as the gf845 below.
ACDelco GF845 & original FPR purchased from WS6Store. Also tested with similar results
Oem filter design
Last edited by JimMueller; Aug 8, 2023 at 11:04 PM.
From: Halfway back on the Highway to Hell...again!
Whatever it takes to plumb in a filter. About the most you'll get away with using the the C5 filter is a 255lph before it blows through the regulator. Now there guys out there that will say they have this and that using that filter. Well I've dealt with more than 10 that run a little above 60psi to as much as 80psi with 255, 340 & 450lph pumps.
So they were immediately changed over to an inline, 10 micron filter and an actual adjustable FPR. Problem solved.
You can use a OE style filter, they flow just fine. But I rarely use 3/8 or AN06 line. Most of my builds use AN08. But even on my wifes show car is just AN06 with a good ol Summit in line 10 micron filter with a very old FAST FPR that still works great.
@SAPPER
Agreed, I've tried three and all have pressure problems.
OReilly's says the LS1 filter flows 1GPM, which is 230lph compared to the 340lph pump. I presume I should have a filter that flows >1.5GPM (340LPH)? I'm having problems locating an OEM-style filter of the correct size that is documented to flow >1GPM. Would it be safe to cap the return fitting (if such a part exists) on my C5 FPR for now, then add the separate return line directly from the FPR in the engine bay?
Last edited by JimMueller; Aug 9, 2023 at 09:43 PM.
Due to being short on time, we moved the OEM Wix 33311 to behind the rear driver seat, and the FPR near the original OEM filter location. Feed is 3/8 from tank to filter, 3/8 from filter to FPR, and 3/8 to rail inlet. Return between FPR and tank is 5/16. Set the FPR at 58psi on the rack, it's been showing 55-59PSI on the gauge. Been holding real well except for once last night where I got on it, and pressure dropped to low 40s... letting off throttle returned near 58psi. What else should I change to keep the PSI steady all the time?
From: Halfway back on the Highway to Hell...again!
The voltage is fluctuating. You need a hotwire kit. As much as I hate to say it, as I completely despise Racetronix, you'll to to errrr.......buy one from them. Or build one. I suggest the latter. It's not hard. Some 12 & 14ga wire, a 40A relay, an inline fuse and some terminals
Our feud dates back to 2005...nufff said.
But your call. You need to keep a consistent voltage the pump.
From: Halfway back on the Highway to Hell...again!
Fuel slosh maybe?? Sucked the basket dry and not enough coverage to keep basket full. What brand pump?
Kinda tossing darts here since I don't know all the exact specifics of the build.
I know what fuel starvation feels like, I had plenty of that in corners and straight line with the prior WS6store 255lph kit that didn't include a bucket. Uncovering the pickup sputters and has an uncontrollable delay. This psi drop recovered as soon as I reduced throttle.
Off the top of my head...
* 98 Z28 with 99-02 plastic fuel tank.
* Trap door cut for 98 fuel sender
* This pump assy & hotwire kit, plus a new locking ring:
* used metal fuel filler neck
* new rubber fuel filler neck
* used filler neck shroud
* new fuel cap
* new evap purge valve
* Bought a new evap canister, but couldn't figure how to remove the old without any damage, so using what came with the used tank.
* after fighting wirh ws6store, acdelco & wix c5 fprs, bought fuelab fpr
* Adjustments in fuel lines to place Fuelab fpr in oem filter location. 3/8 feed, 5/16 return
* Adjustments to move oem filter between fpr and tank, its mounted near vertically on the exterior chassis behind rear passenger seat
* fuel psi gauge adapter between ls3 rail inlet and feed pipe
* egr harness plumbed into Schroeder valve to scan fuel psi in hptuners
I've attached my running research on the FPR issue. Current photos near the end.
Edit: I drove it ~40 minutes late last night to touch up the tuning with the more stable pressure. No problems at all, took it up to ~5500RPM in 5th gear at part throttle without a problem. Driving home through the city, at a stop a guy complimented me on the car and asked me to do a burnout. Wouldn't you fn know it trying to light up the tires from a stop caused the pressure to drop... that was embarrassing. But the log showed PCM voltage in the mid-13's when it dropped.
Last edited by JimMueller; Aug 20, 2023 at 05:13 PM.
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FPR swap 
