3rd Gen Fuel Filter and Low Pressure Pump System

Just check the fuel pressure on the port injection rail.

 

Staring at this filter housing and reading some stuff from DW and this thing is starting to make some more sense. So Pump starts up and pulls fuel into it through the sock. It pushes fuel into the filter assembly. Fuel only has the option to leave through the two holes here. The big guy is obvious. That's what goes to the tank hanger and fuel lines. The little one, now that's a little different. I'll get to that.

The fuel that goes down through the big barb goes through some random bends until it goes over to the main fuel valve. Now this guy is actually the fuel regulator despite the other one having that name (makes no sense). Fuel both goes through this valve and around it. Fuel that goes through it goes through the plastic screen and out the nipple. That fuel bleeds out of the holes marked below and back into the tank. The rest of the fuel goes past the valve and into the fuel lines.

So it's flowing backwards from what I originally thought. Fuel pressurizes everything here and when it gets too high, the valve opens and lets fuel back into the tank. Easy. That's the FPR or more importantly, the pressure limiter. It's main job is to ensure the pressure in the lines does not rise too high.

Also, all that fuel that bypasses through the holes goes out and helps fill the 'surge tank'.


Now onto the other valve. First off fuel leaves the filter above through the other hole on the right. It has no choice but to enter the valve through the plastic screen (the little white thing on the valve in the bottom right corner of the picture). It overcomes the spring, which creates pressure. When it reaches a certain amount it flows into a tiny little 3/16 hose which goes to a barb on the pump assembly housing. That further reduces down to a smaller house which leads to a pinhole.

Ok this little guy is the hole that allows fuel to flow into the pump assembly, creating a sort of surge tank. It just lets fuel pour in naturally.



And this hooks to that opening. It has a pinhole right here that you can barely see. That's coming from the 2nd valve with the tiny hose.

This I believe is what DW refers to as a Venturi jet pump. The fuel is pushing out this tiny hole which effectively is now pressurized via a venturi (a pressure inducing nozzle) which basically creates a fuel jet that PUSHES fuel into the surge tank through that opening in front of it. The 2nd valves ONLY PURPOSE is to push fuel into the fuel pump assembly so you don't get fuel starvation from fuel slosh.



So you kind of need the pressure regulator (fuel main valve). DW states that you can add hose barb fittings to the pressure relief valve to reenable it's use....so maybe we can still use it. I'll have to find that fitting if it exists.

For the Venturi side. Don't need it at all. It's a plus though. Just keep your tank filled with enough fuel that the surge tank naturally maintains fuel. DW recommends drilling 3/8" holes into the bigger pump housing 2" above the base to allow gravity to fill the "surge tank", but fuel starvation could occur below 1/4 of a tank of fuel.



Alternatively you could convert to a return system by putting an FPR into the works and pipe the return line into the tank.

I'm still curious to know how it will run without that main pressure regulator valve in the works.

 

Alright, here we go. Two options here. Keep the filter and valves, but those valves are not designed to work with a higher flow pump. Just talked to DW about this. Basically they are going to change the flow rate of the pump. So if we increase flow from the pump, the valves open earlier and we actually end up with less pressure than with the factory pump. Now the pump works harder to try and compensate. It's constantly fighting that stupid little valve. Not ideal, but it works. Retain the Venturi as well so your surge tank stays filled.

Option 2. Run an external FPR just outside the tank. Set it at the max level that our fuel pump is set to flow (we'll have to ask Mat on that one). Vent the vacuum reference up high or run it to the engine vacuum source so it opens with boost. Run a return line back into the tank. Use a bulkhead fitting for that. Run that to a Radium Venturi jet: http://www.radiumauto.com/Venturi-Jet-Pump-Kit-P760.aspx and plumb that so it feeds fuel back into the surge tank to keep it filled. This little guy uses the return flow to pull fuel from the tank and puts both back into the surge tank to keep it filled. You can run the return line alone into the tank, but it won't flow much to keep the tank filled enough. Comes with 3 fittings to fine tune flow rate to avoid over-restricting the return flow. It's designed for saddle tanks and dual tanks, but will work to fill a surge tank.



In a nutshell though that's it. Running it without that those two valves is going to be not great. You lose fuel flow into your surge tank which can lead to fuel starvation (have to keep your tank filled with enough fuel, and you have to drill your housing), and you run the risk of overpressuring your fuel system. Mat's system will probably keep it in check...UNTIL you run it hard and let off the throttle and it has a bunch of fuel pressure with nowhere to go.

This wouldn't be that detrimental on an N/A taco...but with boost, you need to avoid letting it run lean.

 

Not that it matters much, but the OEM pump is a "brushless DC motor" (aka a 3 phase motor). It is pretty much the same as how RC airplane and quad-copter motors work.

Without more information on how the OVT pump upgrade works, it's a bit of a mystery on how this should be done. I would assume you want a check valve at the bare minimum, and an in tank regulator would be ideal. An external filter and regulator with a new return line would probably be the best, but obviously that would require you to add a new return line somewhere.

 

The DW300M that OV provides for his turbo kit has an internal check valve, so unless it doesn't preform well then no need for an additional check valve.

I suppose you could try and find another toyota compatible regulator to put in the housing (maybe the lexus 3.5L turbo turbo has one), but having it external would be easier so you could adjust as needed. Plumbing the return line would be easy. If you remove the filter housing, then an external FPR with return would be the best option for the surge tank.

 

Missed the internal check valve detail.... Do you really think a surge tank is necessary? I mean it's not like you're going to be pushing 1000hp with this setup right? Or are you intending to go all out? If you're looking at a surge tank setup, maybe it would be better to just start from scratch and not bother with the OVT in tank upgrade?

Just a thought.

 

You don't need to add a surge tank. The issue is if you remove the filter housing, you remove the factory feature that fills the pump housing (which acts as a surge tank). If you remove the valve and jet that fills it, your truck will starve itself when the fuel sloshes around when it gets below a certain level. DW says less than 1/4 tank.


Side note, the Lexus LS500 F type uses the same FPR valve so the factory one theoretically should be ok at low and medium boost. Not sure about pushing high boost with the port injector upgrade though.

 

Ah, sorry. I misunderstood your diagram/description above. That makes a ton of sense. It's amazing how someone can make a fuel sender so unnecessarily (seemingly) complicated.

 

I've been re-reading through all of Mat's old posts about his development of the fuel controller and saw a few things. His fuel control map shows that he tuned the ECU/Fuel Controller to control pressure from 43 to 95 psi. So if he did that, then he should have precise control of the fuel pressure and a regulator is not needed. If it ever exceeds 95 psi then the fuel pump's internal safety bypass would activate as a failsafe (though not desirable because it would cause a fuel flow interruption), but with his controller, the pump shuts off when the rail sensor sees too much pressure.

That being said though, it doesn't matter because if the factory FPR valve remains in the mix, fuel pressure at the rail won't exceed whatever that is set for. I suppose that's the question. I'm going to try and rig up a flow test on the pump housing today and see if I can find when it opens.

So by that logic....wouldn't we need to remove the FPR valve for the pump to see it's full potential? Mat tuned this all under stock constraints so I suppose he would know best. I'm assuming he tuned this all with the two FPR valves still in the tank, so everything is tuned to work that way.

He also mentioned that the ECU only commands the factory pump to run to about half it's possible voltage. His controller changes that and allows it to run up to 14v. Which begs the question: if the fuel pump never outputs high pressure, then why is this valve even in there except to provide flow to the surge tank. Emissions regulation requirement?

 

The surge tank valve started flowing at about 37psi. After I capped that one off, I got up to about 95 psi before the main valve started to vent.

So by that logic it's really set up to hold at roughly 37 psi constant (although realistically probably higher) but with an overall surge of 95 psi to vent before the pump's safety goes.

So adding in a small venturi valve that runs at about that 37psi or even up to id say 60psi and you would be fine. You get your constant relief to maintain a midway psi, you get a valve to fill your surge tank, and your pump handles anything over 105 psi...IF it ever even sees that.

By what Mat said regarding the factory pump's voltage being purposely set low, that valve probably never saw use. Granted with his new controller it could routinely see 95psi. I'm guessing that is how he was able to tune the 95 psi into it. Makes sense now.

 

Just got back from a week long fishing trip, and just quickly skimmed over this thread; haven’t had the chance to really have a good ponder on the pump drawing, pics and diagrams that James kindly provided so atm its very over my head. But my initial thought is I hope it won’t be necessary for us to go down this road and re-engineer a solution for the pump. I would hope Ovtune has worked this all out already as kits are already sending out additionally this is a bolt on turbo kit even with the fuel pump upgrade it’s OV approved, supplied and installed/tested on his personal truck. Since I wasn’t piecing out a custom FI setup this time around I was more under the impression I can sit back, relax and wait for my kit to come and break out the instructions booklet while sitting on the throne in the washroom. That said tho, excuse everything I just said if the intent for the pump mod is simply for an added extra measure of protection for those wanting to add an external filter and due away with the internal.

 

Meso said he didn't have instructions for the fuel yet, but I'd guess that OVT's setup is literally just swap the pump. Since the internal FPR can run up to his max pressures, then there is no reason to remove the internal valve. The only reason to remove it at this point would be to run an external filter because the filter is in a sealed housing integrated with the FPR.

Sounds like Meso is going to run it without the filter and FPR and see what happens. I can't say for sure yet whether it will cause any issues, but I suspect it may be fine since the pump controls fuel pressure. The only issue is the lack of Venturi Jet for filling the surge tank. I'm drawing up two setups right now to address this.

If you don't remove the factory internal filter though then this whole subject is moot. This will be something that will only matter if you want the piece of mind of an external serviceable filter.

 

I guess MESO is the self-volunteered guinea pig for us on that one. I will probably stick to OV’s instruction to a T for the initial install then slowly make changes as we discover and find better work around/ solutions. Thanks for looking into this

 

No problem. I'll probably throw everything on mostly as intended at first just to get moving, then come back to it later when I have more time and change things to the way I want. I've got a powermax kit and plan to run 14psi (for now).

 

I’m exactly in the same boat. Powermax at a 14psi target for now then changes, reliability mods with progression and development.

 

I too will be in that boat of 14psi. Considering this subject being an issue, I reached out to urd to see if they had a fuel pump upgrade for the third gens. He responded that They do not have a conversion kit “YET”. It seems he is also aware of the complexity of the system in tank with it being returnless, 2 pressure regulators and the a/c brushless pump. but sounded like he’s working on a solution as well. Either way, I’m sure as time goes on, this dilemma will be figured out. I’m surprised that ovtune has not yet shed some light on this in a more detailed manner.

 

I've been talking to some fuel system companies and they have been painting a more clear picture on the 'why' of OEM systems. They do everything for a reason and it works.

So first off, let's touch on some of the why. It all revolves around Pulse Width Modulation. Long story short, it is better for the pump to run in PWM versus constant-on in instances of high fuel loads with higher horsepower applications. Think about at full throttle vs cruising. If your pump is pushing 300 lph at WOT and using most of it, great. What if it's pushing 300 lph but only using 10%. In a return system it puts 90% of fuel back into the tank, now heated by the engine bay. That's a lot of wasted fuel and a lot of strain on a pump that has to work constantly.

Throw in a PWM pump though and it takes less effort to run, making it last far longer (OEM's typically run the life of the vehicle), generates less heat in the tank, and now you don't have to recycle your unused 90%. This is accomplished using pressure sensors and a variety of other engine inputs, like throttle and voltage. The beauty of this system is that a fuel pressure regulator really is not needed at all. The pump does all the work. They do have them though, and I'll get to that.

PWMs are complicated because they need fuel controllers (thank you OVT for your custom controller), but in the end mechanically simpler and OEMs use them because they are far more reliable, and are better with emissions. Return systems generate a lot of evap vapors because the fuel returning is hot enough that it's evaporating in the tank, which builds up pressure that needs to be vented. Not only that but the new design of returnless system generally all revolves around the tank hangar, or reservoir.

I've looked at many different versions of these systems and they all really look the same. They all have a tank, filter, pump, regulator valve, and fuel venturi system. I'm going to cover the importance of some of these and why we MUST have them. Sure you can run without some things, but remember they are there for a reason.

The reservoir. This is a late addition to newer vehicles to help in a few ways. Fuel slosh is the major reason. Without this, running your car near empty would be problematic. Newer systems are designed to run with as low as a gallon of fuel in the tank. Think about how hard that would be when that gallon is distributed across a 48" x 24" surface, and that's just idling! Now add in lateral force and your car stalls pretty instantly. The tank serves a few purposes though. It ensures a constant source of fuel for the pump, sure. But it also serves to COOL THE PUMP. PWM pumps run a decent amount of amperage so they can get little warm. When the fuel level is low and the pump is no longer covered, you increase temps in the tank and evaporative emissions. So you keep that tank filled and a constant recirculation of fuel. They are designed to be constantly overflowing. This cools the pump. It also creates a pressure (from volume) to essentially help the pump pickup fuel. So having it filled pushes more fuel naturally into the pump, versus the pump desperately trying to pull in fuel on it's own. The tank is important.

The filter. They put non-serviceable filters in the tank because they are less likely to see contamination, so they aren't as worried about changing them out. They also serve to soak up some fuel and help with the previous point above. You can definitely run an external though for piece of mind. This isn't critical, just manufacturers trying to reduce components and possible leak points. Keep your fuel cap closed (versus accidentally driving around town with it open) and ensure you use only good fuel sources (which includes keeping any fuel cans you use clean) and the filter really shouldn't be a big issue. I totally understand wanting to do better here though.

The regulator. This is a safety valve. No more. That's why they are set up to vent at such high pressure. Some returnless vehicles come with slightly different versions, but they all have them. Pressure regulation is 100% controlled by the pump. An external regulator is not needed at all. So why does OEM have them then. A couple reasons.
1: Safety. If the fuel controller fails, they are a backup.
2: Sudden excess fuel pressure. The pump can simply dial back to allow pressure to bleed off, but this can assist with things such as full throttle to zero throttle events where pressure is high and then suddenly not needed. It ensures the pump's internal PRV (pressure relief valve) is not activated .
3: Ignition-off events. When you turn off the engine, the injectors close but the pump still has inertia. You have built up pressure and the pump will add a little more still, and it now has nowhere to go. This valve ensures it drops down to (in our tacoma's case) 95psi.

The Venturi valve. This is CRITICAL. Every returnless vehicle with a reservoir has one. Some have up to 3. It's sole job is to keep that reservoir overflowing. Imagine not having one. You would need to keep your tank full enough that your reservoir has enough fuel to cover your pump to keep it cool (about 6 inches). You need to keep it full enough that under high lateral forces your pickup remains submerged. Even with fuel in the reservoir, your fuel can pool up to one side enough that the pickup sees air. Without the valve the reservoir can never exceed the fuel tank's level (remember we have a long tank, not tall, so a half a tank of fuel may actually only be 4-5 inches deep). It is fed from a hole at the bottom. You could drill holes in your tank to allow gravity to fill it, but even though it only helps so much. Even if you drive like a granny and never have fuel slosh (impossible btw) you still need to keep the pump cool.

It's in our best interest to maintain these functions. Keep in mind that you can run everything in the pump assembly stock with the new pump and turbos and nothing will limit it. This design will allow that pump to run up to 95 psi no problems.

If you are still dead set on running an external filter then you have to take steps. You can probably run without a regulator just fine. Sure you're going to have pressure spikes that the pump will have to bleed off. That's ok. It's just a safety backup. If you want to incorporate one into the system, you can just put an external bypass fuel pressure regulator just outside the tank set right at 95 psi. Don't boost reference it. It's only there to prevent pressure over 95 psi. That's it's sole job. Caddilac's and some GMs have a poppet valve for this. I'm going to see if I can find something that can be tied into the line in tank that will do the same thing. Trick will be finding a 95 psi valve. This is just for piece of mind. You really don't NEED this, but you should have one just in case. Without it you are just going to run the risk of having your pump do a PRV event and have a stutter as your fuel pressure suddenly drops off for a short duration. It won't drop to zero pressure or anything so there should be very little risk of running super lean. If you look at the bottom of the pump, it's just a small pinhole. It won't dump all the fuel at once or anything.

Get a venturi jet or two to keep that reservoir filled! This is critical or you are just going to run into fuel starvation issues. Think about this. If you run the factory pump from the toyota recall on this turbo and it has one of it's spasms and stops fueling your boosted engine, even briefly...you could grenade your engine. Fuel starvation from slosh is the same thing. If you do a launch with low fuel, you are going to hurt your engine when you suddenly run it super lean. You want to do everything to ensure you never go lean with turbos. The alternative is keeping your fuel tank filled. What's the magic level? 1/4? 1/2 tank? I don't know.

Bottom line you can run without this stuff, but you are going to seriously increase your probability of problems. My intent is to try and find a good setup that meets all the dockets yet allows me to remove the factory filter.



I do have one question for Mat though. Is the new fuel controller program set up to run with boost pressure reference? I'm assuming it's been modified to reference boost pressure and compensate fuel psi to offset the positive boost pressure in the manifold.

The pump can be commanded to do this easily. Since our pumps are PWM, an FPR does not control the pressure at all, so having a boost referenced FPR isn't going to be as effective. Set it too low and our pumps won't be able to run at their needed potential. Set it at 95 psi and your pump hits it's PRV limit at 10 psi boost (it would run it at 105psi to compensate). You'd have to set it at 95 minus max boost to work properly (@ 15 psi boost you would set your FPR so it's 80 psi fuel max - Once boost referenced it would drop to 69 psi fuel at full vacuum then max out at 95 psi fuel when at full boost). But again, your pump can do all of this if the fuel controller knows manifold pressure. Using a mechanical FPR would be a "dumb" way of doing it. The electronic fuel controller is far more efficient and controllable.

 

Beautiful read. Thank you for typing that all out! Appreciate all the technical chat from all you peeps. Shits interesting as fuck.

 

Y’all see the fuel pump upgrade instructions from ovtune? Looks like the controller he provides plays a key role.

 

Returnless boosted Mustangs have been running around for a long time deleting the what they call the PPRV with no issues. It's pretty much a combo that held pressure when the car was shut off but also bled off extra pressure. It was found to be a restriction in high hp applications and was commonly deleted.

While not apples to apples it's a really similar concept.

https://www.moddedmustangs.com/threads/pprv-delete-what-is-it-and-why.234591/