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Discussion Starter · #1 ·
So after my PPRV delete Ive started to smell fuel then check and see an injector oring popped out.

Initially I thought i had bent my fuel rail installing my nitrous outlet adapter so I could wire in a fuel pressure gauge but then one popped out on the drivers side fuel rail too. I tried a thicker top oring on the injectors with no luck still pops out.

Ive been very lucky to catch this each time without having a fire.. that may not always be the case... so I have stopped driving the car.

Ive read one person had the same issue and upgraded to BBK fuel rails and the issue went away.

I suspect I should reinstall a working PPRV (but you cant seem to buy these stand alone unless anyone knows of some trick there).. I would have to buy a fuel fuel assembly... with pump i believe and remove the new PPRV to install back into my car. Though I am curious if anyone here has any other ideas or options.

Thanks as always.
05 crown victoria, supercharged/intercooled.
 

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So after my PPRV delete Ive started to smell fuel then check and see an injector oring popped out.

Initially I thought i had bent my fuel rail installing my nitrous outlet adapter so I could wire in a fuel pressure gauge but then one popped out on the drivers side fuel rail too. I tried a thicker top oring on the injectors with no luck still pops out.

Ive been very lucky to catch this each time without having a fire.. that may not always be the case... so I have stopped driving the car.

Ive read one person had the same issue and upgraded to BBK fuel rails and the issue went away.

I suspect I should reinstall a working PPRV (but you cant seem to buy these stand alone unless anyone knows of some trick there).. I would have to buy a fuel fuel assembly... with pump i believe and remove the new PPRV to install back into my car. Though I am curious if anyone here has any other ideas or options.

Thanks as always.
05 crown victoria, supercharged/intercooled.
I have done the pprv delete several times to several different cars and never had this issue. If u swapped rails 8/10 its the installation not back at the tank

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The injector leak problem is not a PPRV related problem. Assuming the fuel rail holes are the correct diameter, the probable cause is a misalignment between the fuel rail and the intake manifold. When the injector gets canted one side of the o-ring is overly compressed and the other is insufficiently compressed. After usually only a short time the leakage begins to appear. From first appearance to a dangerous leak is surprisingly quick.

If the manifold is OEM, then I would recommend a set of Fore Innovations fuel rails. They are well designed (injectors are not canted) and pleasing to the eye. If the manifold is not OEM then your best bet would be a set of fuel rails from the manifold manufacturer, who should build fuel rails to match his manifold. Bore centers, intake port centers and injector centers on a Modmotor are on 100mm centers. The fuel rails need to duplicate this spacing or you will have leakage issues. Also be sure you use the correct o-rings, both size and durometer hardness. You want the o-ring to tolerate the heating and cooling cycles the motor experiences without hardening. If they begin to harden leaking will not be far behind.

The PPRV will make starting more OEM like than a fuel system w/o a PPRV. There are several aftermarket PPRV sources that usually end up being fuel injection component suppliers or fuel fitting suppliers. They ate typically available in -8, -10 and occasionally -12 AN sizes. The -10AN size is adequate for almost any build out to about 2000 HP.

The aftermarket PPRV's are not quite as good at sealing up when the engine is off as an OEM alternative but the aftermarket PPRV's flow significantly better than the OEM variety.


Ed
 

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The injector leak problem is not a PPRV related problem. Assuming the fuel rail holes are the correct diameter, the probable cause is a misalignment between the fuel rail and the intake manifold. When the injector gets canted one side of the o-ring is overly compressed and the other is insufficiently compressed. After usually only a short time the leakage begins to appear. From first appearance to a dangerous leak is surprisingly quick.

If the manifold is OEM, then I would recommend a set of Fore Innovations fuel rails. They are well designed (injectors are not canted) and pleasing to the eye. If the manifold is not OEM then your best bet would be a set of fuel rails from the manifold manufacturer, who should build fuel rails to match his manifold. Bore centers, intake port centers and injector centers on a Modmotor are on 100mm centers. The fuel rails need to duplicate this spacing or you will have leakage issues. Also be sure you use the correct o-rings, both size and durometer hardness. You want the o-ring to tolerate the heating and cooling cycles the motor experiences without hardening. If they begin to harden leaking will not be far behind.

The PPRV will make starting more OEM like than a fuel system w/o a PPRV. There are several aftermarket PPRV sources that usually end up being fuel injection component suppliers or fuel fitting suppliers. They ate typically available in -8, -10 and occasionally -12 AN sizes. The -10AN size is adequate for almost any build out to about 2000 HP.

The aftermarket PPRV's are not quite as good at sealing up when the engine is off as an OEM alternative but the aftermarket PPRV's flow significantly better than the OEM variety.

Ed
There well.said lol

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Discussion Starter · #5 ·
I want to believe you guys that its not the PPRV delete but it has to be because of it (whether its tune related because my tune was over compensating for the pressure lose, Im not sure).

This car has the stock intake manifold (ford racing one), its been supercharged for 5 years. 4 engines, 4 fuel pumps, two sets of ford racing #39 injectors. In 5 years i never once popped an injector ring... until the same day I had the PPRV deleted and multiple times after.

Deatschwerks support stated this about my PPRV (that its not only the check valve as you describe but it also is a pressure by pass.

"Although, you have a unique circumstance. Your check valve is built into the same thing your PRV is in BUT they are not one in the same. They are in the same piece but are separate inside. That being said all your issues seem to stem from the same piece. "

Thanks Ed, im going to look into Fore Innovations fuel rails.
 

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Discussion Starter · #6 ·
When I datalog my driving pressure doesn't seem high or abnormal... I think its something to do with starting pressure. Like when the car is sitting the fuel pump check valve is holding the pressure for me for a quick start around 40psi~... but when i turn go to start the car the pressure jumps to 75psi or so and then a oring pops out (I believe)..
 

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Discussion Starter · #7 ·
My tuner is suspecting the same thing as you guys :( that the rails are misaligned or similar).

Hes stating to put the stock orings back on and try to align the rail again. Which I will do and report back.

I just dont get how this engine and rails/injectors have been in this car for about or over a year. No issues. The first drive home after the PPRV delete I smell gas and see the pushed out oring on one injector (its always one injector from what I have seen).

Something with this PPRV delete has helped this issue arise...
 

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The PPRV only allows the fuel lines to maintain a positive pressure when the engine is shut off. Service manuals will tell you to relieve this pressure before working on the system by venting it at the Schrader valve, usually on one of the fuel rails. The reason the design engineers wanted the PPRV in the first place is to allow quick engine starts. If the fuel rails and fuel; line have drained back to the tank then the engine can not start again until they are refilled. The PPRV eliminates this time delay by keeping the fuel lines fully charged —*nothing more and nothing less.

The occurrance of the other maladies at the same time is nothing more than coincidence. With respect to your engine running fat because of an over pressure in the fuel delivery system, that would be hard to engineer if you are running the OEM ECU. Ford uses something called a Fuel Rail Pressure Sensor or FRPS. It is the FRPS' job to inform the ECU of the fuel rail pressure at all times. When pressure falls below target pressure the ECU will increase the injector's open time to compensate for the reduced furl rai pressure insuring that the cylinder is properly fueled, Similarly when the pressure rises above the system target pressure while the engine is running, the ECU will reduce the injector's open time to properly match the fuel shot to the engine demand.

Your PPRV whether in the system or removed from the system is not the cause of the o-ring leakage issue. The leakage is either associated with canted injectors or injector o-rings that are incorrectly sized or made from the wrong o-ring material — it is really that simple.



Ed
 

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Discussion Starter · #9 ·
Thanks Ed. I've got the rail off. I need to swap all the OEM top o-rings back on (and touch them up with some fresh engine oil)... then I will try to seat all the fuel injectors into the manifold until they bottom out, then carefully align and screw in the rail on top. Should I not be pushing them all the way into the manifold? I figure thats what the fuel pressure does anyway.

I'm being told and have read that the PPRV in my crown vic (it looks the same as the mustang one in pictures) is not only a check valve for holding pressure for making starts easier. It also bypasses pressure (I dont know the exact PSI I guesstimate 60psi~) and it lets the excess pressure bleed off into the tank.

Can we agree on that part? or is that wrong?

Picture: https://drive.google.com/file/d/1pXKMKayeemxGRA6uyVy-Sv-tFRGKIjgm/view?usp=sharing

the line that goes from the pump out of the tank is where the check valve function comes into play, the 3rd line that goes back into the take is the pressure regulator part.

Or am I wrong in that understanding?

Thanks as always Ed, your knowledge is priceless :)
 

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You are correct about the pressure relief capability of the PPRV. Unless you are supercharged it is improbable (not impossible) that you would find need for the pressure relief provision. The supercharged cars are a different story. If you run a 3 BAR base fuel system pressure (Ford uses 2.7 BAR) and add 23 psi of boost your fuel system will be running at 68 psi. Most of the electric fuel pumps have a built in pressure relief that is set around 75 psi to protect the pump from damage. The PPRV among other things is a fail safe so that as fuel pressures begin to approach the fuel pump's built in pressure relief blow off point the PPR will go first saving the fuel pump from using it's built in pressure relief.

So why do this why not just let th built in relief do its thing? The problem comes in reseating the internal valve. They have a hard time reseating without some type of continuing leak, which starves the engine for fuel. By using the external PPRV, the pumps internal relief never has to be used and the external if it does goes bad is relatively inexpensive and easily replaced. Here is a pic of a Cobra Fuel Pump hat with an OEM PPRV that I pulled off the net;

pprv.jpg

The output lines from the two fuel pumps are merged into a "Y" fitting to provide a single feed line into the PPRV and then out to the engine. See pic above. The PPRV has a single out port and it also has a pressure relief bleed off which is the small nipple pointing downward (astually because of picture orientation it points up in the pic) to relieve excess pressure above its blow off setting.

The pressure relief will work more often than not in boosted engines and only occasionally, if at all, in n/a applications. For n/a applications it is a lot like your appendix. It is there bt doesn't do anything.

The item you are illustrating on you pic may well be a PPRV for a CrownVic but it is a different PPRV than the one used for a Cobra. That said their function should be identical,

Ed
 

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Discussion Starter · #11 ·
I am supercharged. but only 8psi. I believe my max fuel pressure needed is only 48psi. which I only ever see that around full rpm/WOT (and when I let off a WOT for a second or two on the datalogs it will bounce up pressure until it can compensate for the quick throttle body closing and the pump delay of making pressure for the WOT in a returnless system.

Everyone believes the pressure should not be blowing out the injector top orings. my KOEO pressure before deleting the PPRV was always 40-50psi (but dropped fast because it was failing/leaking on the pressure regulator side). With the PPRV deleted KOEO the pressure builds to 75PSI and holds there (thats the only time I have ever seen the pressure that high) If I key on, engine off without starting. So to me that is the new variable that pushes my orings out... though I always try to start without any delay on my key on process so the pressure hopefully doesnt build that high on start (but I cant really tell because my datalogger resets during key on and my external fuel pressure gauge.

I just pulled the injectors. cleaned them. restored the stock ford racing #39 top orings. Oiled all the orings up slightly. Pushed them into the manifold tell the stopped (kinda feels like they click but they just stop eventually). seated the rails. there is little to no play with only slight minor adjustments to the injectors standing up. I tried to line them up perfectly so they look to be standing straight up on the front/back on both sides.

I will likely test tomorrow. let all the fuel smell go away.
 

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I am supercharged. but only 8psi. I believe my max fuel pressure needed is only 48psi. which I only ever see that around full rpm/WOT (and when I let off a WOT for a second or two on the datalogs it will bounce up pressure until it can compensate for the quick throttle body closing and the pump delay of making pressure for the WOT in a returnless system..
Unless you are running the Ford recommended 39.15 psi base fuel system pressure you will be running the 3 BAR 43.5 psi that most injectors are flowed at. If you add your 8psi of boost that means you peak fuel pressure should approximate 43.5 + 8 or 51.5 psi. If yo are running a modified (from OEM) returnless system you will need to do some PID tuning or you will get spikes into the 70+ psi range. Go to the TToC under Tuning and open the thread Returnless System Fluctuations II. Go to post #42. It is done by Jerry Sutton. He will give you chapter and verse on what they did (in the tune) to fix the pressure spikes. It works.

Ed
 

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Discussion Starter · #13 ·
I believe Im running at the 39.15 base fuel but I would have to ask my dyno/tuner.

This is what he had to say earlier which is similar to what your saying Ed. But Ive adjusted the rail now 3 times so I suspect they are just sitting slightly too high. The crown victoria stock rails are different then the 99-04 rails slightly. I wonder if they just sit higher on the bore/holes and the high pressure is too much for it. I dont know. I will give that a read. Thanks.

Hey Justin – We’ve built a lot of 03-04 SVT Cobras over the years and I don’t remember ever needing to remove the PPRV. Typically, if your fuel pressure is fading at higher rpm under boost it’s because you need more capable fuel pump(s). Also, a spike to 75-psi fuel pressure is not unusual and your injectors/fuel rails should be able to handle that without springing a leak. I also don’t think deleting the PPRV would cause that. It makes me wonder if there is a fitment or alignment issue between your fuel rails and injectors. Maybe something has shifted or worn over the years? There are parameters in your calibration in the Returnless Fuel Pump Scalars that can be adjusted to minimize the larger fluctuations in fuel pressure (Fuel Pump Gain Derivative Term, Fuel Pump Gain Integral Term and Fuel Pump Gain Proportional Term). However, I doubt that those really need to be adjusted in your case. Doesn’t seem like you should have to go to a different size injector o-ring than what worked fine in the past. I guess I’d recommend focusing on the fitment of the injectors and fuel rails.

and then this little snippet related to fuel PSI a while ago:

So, as boost goes up the fuel pressure should go up so that it maintains the 39-psi pressure drop across the injectors (or whatever fuel pressure is targeted in the calibration).
 

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I believe Im running at the 39.15 base fuel but I would have to ask my dyno/tuner.
It is not necessary to ask your dyno tuner where the base fuel system pressure is set at. Chances are he did not change it and may not know what it was / is set at.

You can measure this very easily. Put a fuel pressure gauge on one of your fuel rails. Disconnect the vacuum reference line to your FRPS. Start the car and read your fuel pressure. With the vacuum reference line disconnected you will see the base fuel system pressure your system was set to.

This is what he had to say earlier which is similar to what your saying Ed. But Ive adjusted the rail now 3 times so I suspect they are just sitting slightly too high. The crown victoria stock rails are different then the 99-04 rails slightly. I wonder if they just sit higher on the bore/holes and the high pressure is too much for it. I dont know. I will give that a read. Thanks.
Earlier I had also commented about the o-ring material and sizing. If the size of the 0-ring is a whisker small, for what ever reason, this will be a problem. If the o-ring material hardens with repeated exposure to heat this, this will be a problem. If the o-ring material is of a different duriometer than the originals, this will be a problem. Original manufacturer or OEM replacement o-rings are cheap. Use the proper o-rings for starters. When you assemble the injectors to the rails and manifold use vasoline for the assembly lubricant. It is more inert than motor oil and will not attack the o-ring material.

All that said, I still suspect a mechanical fitment issue. The finally assembled components should have the rail settled down over the injectors so the injector tops and bottoms are deeply seated in their respective bores without any misalignments. The o-rings should be nowhere near the entry to the injector pocket, The o-rings should be seated deep in the manifold and fuel rail.

A good fitment test would be if you still had the OEM fuel rails available. Put them on and I bet your leakage problem goes away. If it does you immediately know it is the aftermarket rails and you can go about replacing them with known good alternatives. BYW KB has used the OEM rails at power levels approaching 800 or 900 RWHP! You don't need aftermarket fuel rails for power. You might want them for other reasons.

The other possibility is the injector registration pockets in the rail that you insert the injectors into are the wrong diameter. Pull down the spec sheet from Siemans Deka or any other injector manufacturer, check for the recommended pocket diameter for the injector in the fuel rail. Measure yours. If yours are big it is time to get new rails.

Hey Justin - We've built a lot of 03-04 SVT Cobras over the years and I don't remember ever needing to remove the PPRV. Typically, if your fuel pressure is fading at higher rpm under boost it's because you need more capable fuel pump(s). Also, a spike to 75-psi fuel pressure is not unusual and your injectors/fuel rails should be able to handle that without springing a leak. I also don't think deleting the PPRV would cause that. It makes me wonder if there is a fitment or alignment issue between your fuel rails and injectors. Maybe something has shifted or worn over the years? There are parameters in your calibration in the Returnless Fuel Pump Scalars that can be adjusted to minimize the larger fluctuations in fuel pressure (Fuel Pump Gain Derivative Term, Fuel Pump Gain Integral Term and Fuel Pump Gain Proportional Term). However, I doubt that those really need to be adjusted in your case. Doesn't seem like you should have to go to a different size injector o-ring than what worked fine in the past. I guess I'd recommend focusing on the fitment of the injectors and fuel rails.
Your tuner is correct. His comments about Returnless Fuel Pump Scalars is referring to the returnless fuel pump PID controller. That is what Jerry Sutton provides you with chapter and verse on how to "fix" so the fuel pressure spikes become a thing of the past. Watch the video in Jerry's post and pay attention to what he says. As I commented earlier - it works

and then this little snippet related to fuel PSI a while ago:

So, as boost goes up the fuel pressure should go up so that it maintains the 39-psi pressure drop across the injectors (or whatever fuel pressure is targeted in the calibration).
This is what I just explained for you in post #12

Ed
 

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Discussion Starter · #15 ·
Thanks Ed. I will do that test and report back.

I am not running any aftermarket fuel rails. I am only running stock fuel rails ever (I have never owned an after market fuel rail).

I have a complete set of spare manifold/injectors (both a stock set and another ford racing #39 set)/stock rail on my work bench. I have been test aligning/messing with them and there is just not much play.

I suspect the crown victoria rails sit higher then the 03/04 and 99-04 mustangs and its just enough to not let the top oring seat high enough for the extra pressure. I think the PPRV delete helped my car get the pressure it needed (and a little more).. but if my PPRV was functioning correctly I would of likely seen this issue sooner. So I would agree with all of you that the PPRV delete is not the actual issue or problem. It just helped it come to the surface because of the hindrance cause by it leaking/failing on the regulator part (which maybe is what the few other random people experienced also).

I sent that #42 post from Jerry over to my tuner see what he thinks but great information there.

Picture of stock injector vs ford racing #39 injector. It seems the stock injector has a built in "washerish" piece on the tip that might help push the injector that much more into the rail vs the ford racing one.
https://drive.google.com/file/d/12djIdbtGZ0TjGZ47Iw_bN7RhPerXAyXd/view?usp=sharing

The stock injector sticks up about 2mm higher then the ford racing.
Picture of injectors from the underside of the manifold. Stock injector on top, ford racing #39 on bottom:
https://drive.google.com/file/d/12ju6hcmL263IfCjJjM38p0yxlHnPpaUB/view?usp=sharing
 

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The rails may indeed sit differently on the engine than the Cobra equivalent rails. Recognizing how attentively (isn't that a nice word) Ford watches production costs I would not be surprised to discover they used the same rails on both engines, perhaps with a modified mounting location.

A number of years ago I bought one of the FRPP Mach I crate motors to get pieces for a build I was doing because it was a more cost effective way to go. At the time I needed a set of fuel rails and on a lark tried the Mach I rails. They seemed to fit on the 03/04 Cobra build! I never used them because the guy wanted the bling factor of aftermarket rails but I never forgot the 'apparent' interchange capability.

Because your rails are stock and you are having a leakage problem, I would be looking at the alignments and also the o-rings. If the o-rings are not an OEM replacement, I would try to get some OEM replacements. The problem might be fixable by something as simple as an o-ring change.


Ed
 

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Discussion Starter · #17 ·
From looking at pictures they seem different (tabs, shape of rails).

There is little to no alignment play once the screws are in but there is some. The orings are stock ford racing #39 oem.. they are not the OEM stock crown victoria orings.... should I look at swaping those?

I just dont think the crown victoria rails with the ford racing #39 injectors not fitting as high into the rail as the stock ones can handle the pressure spikes from a PPRV being deleted. Its putting too much pressure on the canted injector or low in the rail injector.

Is there an option of putting a different "tip" on the injector to space it up 1-2mm more like the stock one? or even more? to push the injector further into the rail? and/or will there negative issue with pulling the fuel tip up that much? Maybe not i think that tip goes all the way into the hole and it sits on the washer. ignore me.
 

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Injectors usually come in standardized lengths. If I am not mistaken your are 60mm long. Here are some engineering drawings from MotoTron to help in injector sizing and fuel rail placements. This is a dimensioned side view, all dimensions are in millimeters;

Screen Shot 2021-01-29 at 6.49.35 PM.jpg

This gives almost all the dimensional data you need but is still incomplete. The next image provides the missing info;

Injector_Data_80USCAR__87844.1416363080.1280.1280.jpg

Here you can see where the 60 mm sizing designation originates from. It is the distance between the o-rings. Notice the different dimensions on the top and bottom o-rings. This (along with durometer and material) is why I was suggesting the use of OEM o-rings as opposed to aftermarket. The top o-ring might be the same size before insertion into the fuel rail and MotoTron (along with everyone else) uses a smaller register on top to better seal against the fuel system pressure. OEM stuff is essentially the same price and you know it is properly sized.

This next pic shows the injector manufacturer's preferred assembly stackup from manifold, to injector, to fuel rail.

Screen Shot 2021-01-29 at 6.49.51 PM.jpg

Notice how deep into the fuel rail pocket and manifold pocket the injector is seated,

Although I recognize your belief that the PPRV is causing your fuel system spikes, it really is not. The spikes are caused by how the fuel pressure PID is programmed in the tune. The PPRV is almost exclusively used for maintaining fuel pressure in the fuel rail at the injector after engine shutdown for an easy starting experience at the next start. There is an internal pressure relief the PPRV has, that you can see the discharge port of, in the fuel hat pic I posted above but that is not the PPRV's purpose in life, It really is just a residual pressure valve to make restarts easier.

Ed
 

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Discussion Starter · #19 ·
Your info/knowledge is always above and beyond ha. I just need to get new rails and maybe a new PPRV also but I love the way the car feels with the PPRV gone, the 1/2 shift is amazing

I was researching fuel rails recommendations from back in the day (really looking what people said about the FORE INN one). Then I saw all these quotes of people having the same issue as me. It looks like the stock rails for the most part are not liking 60-70psi+.


Quotes from mustang users:

"I only changed them out because they didn't seal very well over 60psi of pressure. The cups the injectors sat in were getting bent out of shape and weeping fuel. Other than that they worked just fine."

"indeed. mine worked perfectly fine until i added a BAP and i guess the extra pressure did it in because it started blowing #4 o ring...changed fuel rails and it hasn't done it since."

"Thanks young gun. Same thing is happening to me now. Running a bap, modded fpdm and 320lph pump with pprv delete and my rails keep popping o rings out. I even bent both rail tabs like you guys but they still pop out'
 

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... I was researching fuel rails recommendations from back in the day (really looking what people said about the FORE INN one).
The Fore Innovations fuel rails are 100% designed and manufactured right here in the US, Justin. This is the website for the rails I am speaking about, click here => Fore Innovations

I think your best bet for fixing the leak problem will most likely be the Fore replacements. Justin puts a lot of effort into his products in both the fit an finish. These are the oldest parts he offers and he has just updated them again. I personally own a pair of his first generation rails and they are stunning. His new offerings are even nicer.

Ed
 
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