Well.. I disassembled the pump and I found one problem - I drilled too far through the venturi:
http://www.the370z.com/attachment.ph...0&d=1482772816

And you can see how big the hole is:
http://www.the370z.com/attachment.ph...1&d=1482772816

1) Is this damage repairable? If not, recommendations?
2) If I drilled all the way through, we would expect to see much lower idle pressure, no?

A couple of other disassembly pics:
I don't recall this strainer being so black before....
http://www.the370z.com/attachment.ph...2&d=1482772837

And where did all this crap come from?
http://www.the370z.com/attachment.ph...3&d=1482772837

I am going to reinstall without the black venturi just to see the test result. Will report back in a few.

Removing the black venturi piece does not seem to have affected anything, at least as far as reported by the gauge.

Prior to turning the car on, the gauge read 0psi.

After turning the car on, but not starting the motor:
http://www.the370z.com/attachment.ph...1&d=1482777206

After starting the car:
http://www.the370z.com/attachment.ph...1&d=1482777206

After the motor comes up to temp (water temp one dot short of middle.. This is also when my idle starts to go wobbly)
http://www.the370z.com/attachment.ph...1&d=1482777217

And after shutting the car off:
http://www.the370z.com/attachment.ph...1&d=1482777217

Any ideas? Based on your previous post, its likely either the gauge misreporting or a problem with the OEM regulator... I'd imagine the gauge is behaving properly, but I put up the pictures in hopes you can confirm one way or another... So probably the OEM regulator?

Should I go ahead and start hunting for a new fuel pump assembly? Are they the same for the Z and G?
Edit: The part#s are similar, but different. G37: 170401NC0C 370Z: 17040-1EK0B

Running without the venturi installed or running it with the extra hole in it has ruled out the venturi as the source of your pressure spike. Unfortunately Nissan does not sell the venturi jet, so the only way to replace it is to replace the entire fuel pump housing. It will need to be replaced or repaired since the additional hole will either entirely defeat the venturi system or render it too weak for standard use. The car will fuel starve from not being able to recover fuel on the driver side of the tank.

All the black gunk/debris in the fuel pump canister is normal. I dont know where it comes from but its in every stock 370z fuel pump I have ever opened. The strainer being darker probably isnt a big deal yet, looks pretty normal for a well used one. It wouldnt effect the fuel pressure spike anyway as the most it could ever effect, if it were completely clogged up, it would restrict the pumps intake resulting a pressure loss rather than pressure spike.

Since your fuel system is stock, the only possible way for fuel pressure to exceed the regulator setting is if the regulator cannot vent out well enough, or if the regulator itself is damaged/clogged. You have eliminated regulator venting from the equation, so there are only 2 possibilities left. Your regulator is bad or clogged up, or the fuel pressure gauge is reading high.

I would replace the fuel pump module with another one since this is inevitable at this point*, and then if the fuel pressure is still too high according to the gauge, i would either try another gauge or I would just ignore it and write it off as the gauge just reads a few psi high.

*: unless you can find a way to plug that extra hole up with something that will not dissolve in gasoline. Such as machining a custom plug on a lathe and pressing it in, or something.

Another thing you can try, is drilling out the outlet on the stock regulator. I have never had to do this but I do not generally use a stock fuel system. All the cars I work with are using return kits. But I believe that Stillen has their customers drill the outlet on the regulator so it itself can vent better. This might be worth a shot as it could not hurt anything so long as you do not drill too deep into it.

I'll dry drilling the regulator, seems like I don't have much to lose at this point and may as well experiment. As for plugging the hole on the opposite side of the venturi - JB weld makes a couple of epoxy putty products that they say can be submerged in gasoline.. might see if that does it. If I do manage to repair the damage, do you think I drilled out the venturi too much for the 255lph? If I did, what would the symptoms be? low idle pressure? or low pressure while driving? Could I then correct the problem by just upgrading to a 340lph?

Any recommendations on getting a new fuel pump assembly? Used units for the G37 seem to be much less expensive, but the part number is slightly different. Do you know if they use the same venturi piece or regulator?

Also, do I need the little venturi piece if I upgrade to a return system? A new assembly is $350..might be better put towards an upgrade.

Thanks for continuing to provide feedback. Really appreciate the advice! Hope the documentation of my experience in this thread will help someone else!

If you find an epoxy to plug the extra hole with, may as well use it to also bring back down the size of the original hole.

Symptoms from making the venturi too large is that the venturi will become weaker as you will have lowered the pressure differential. The venturi system is used to fill the fuel pump canister, and to transfer fuel across the tank from the driver side. A weaker venturi will do this slower, or not at all. The perceivable side effect would be the vehicle acting like it is out of fuel when it is not. Power cutting out, fuel starvation, etc.

Most G37s use almost the same fuel pump module, but its several inches shorter and not tall enough for the Z tank. You would have to hybrid it together and use your Z top hat and rods with the G37 lower half, or just take the venturi part you need and move it over.

Some G37s use a 350z fuel pump module, which would be entirely useless for you. So you will want to see a photo of the one you are buying first, and make sure it looks just like the one you have. The 350z module looks entirely different on the fuel tank side, so there would be no way to mistake them unless you only saw them from the very top (such as not removed from the tank) in which case they look nearly identical.

The venturi system is still used with a return fuel system, so you would still need to either repair or replace this component.

I do have a complete replacement fuel pump module for the 370z coming out as soon as some suppliers on a few of the components new to my inventory follow through on their end. This new module will not use any components at all from the factory fuel pump module, so you wouldnt needed the stock pieces. But it will require a return system to use it, and it also will not be released for quite possibly several weeks yet at this point.

Awesome! Thanks!

Looks like the JB weld product "AutoWeld" is made for repairing gas tanks... there is a reviewer on amazon that successfully used it on a plastic tank... hopefully it will bond to the plastic the black venturi piece is made of. O'Reilly carries it, so I can try it out tomorrow if drilling the regulator solves the idle pressure.

I think I'll probably shop for a replacement assembly anyway... There is a member here parting out his car so I posted to his thread..

Good to know! I am still mulling over if I want to go E85 with a return setup in the future... my Z is my primary driver and I worry that going up to 650+whp I may start compromising the longevity of the motor and drivetrain. I go back and forth thinking about it..

That has such a nice ring to it

Just rolls off your tongue so nicely! :driving: :driving:

One more question! Perhaps the one I should have led with! Could high idle pressure result in a wobbly idle? It only seems to happen with the car warm and the AC off.

I know..... I know......:eekdance:

If the A/F is clean at the moment it is happening, than it is unlikely related to the fuel pressure. The o2 sensor feedback system will typically adjust for a fuel pressure spike at idle with ease so long as it is not outside its range of allowed correction. If your car has a custom tune that was generated on your car while the fuel pressure had the same profile, its even less likely related.

Ahhh.. I REALLY should have asked you before embarking on this lol.

The good news is, I was able to get an assembly from a wrecked Z for cheap so I will just replace the small venturi piece and call it a day... I would experiment with drilling the regulator, but the assembly I picked up is not 100% as the accident the car was in snapped the rods connecting the hat to the bucket... If i was completely functional, I would experiment till the cow's came home since I could just pop in the replacement.

Based on this feedback, it looks like I should just restore the state to the way it was before since I was tuned that way anyway and it is not likely to be the source of my wandering idle. The search continues!

Thanks a lot for your guidance on this phunk! You are the gold standard for vendors around here.

PS - I'll post a FS thread soon to part out the extra assembly. Should save some headache for anyone else that just needs a small piece.

Swapped out the unmodified venturi piece from my salvage pump assembly.

My idle pressure with it is 65psi... So it looks like it was lowered ~5psi from drilling the venturi just to 5/64...but then nothing gained after that (even after I drilled the whole thing accidentally). I think to start, the venturi system was the bottleneck, but not far after the regulator became the bottleneck... I would speculate that I'd need to drill both the venturi piece and the regulator as directed in the Stillen instructions to get a more normal idle pressure.

But as phunk pointed out - my car was tuned with the idle pressure like this.. so I have decided to leave it alone.

Fuel pressure now:
http://www.the370z.com/attachment.ph...1&d=1482891528

I would try reving the engine and seeing if the pressure falls down. If the regulator needed to be drilled to flow better on its outlet, pressure should fall down when fuel consumption increases.

I'll give it a shot and take a little video... though it will have to wait at the moment as I am in the middle of a diff bushings/cover upgrade... Hopefully I'll have it back together tomorrow evening!

I swapped on the Aero 340 I got from Charles and drilled the Venturi as instructed. I was reviewing the Stillen instruction book after my install to make sure I didn't miss anything and noticed they call for drilling out the regulator as well, but I don't recall seeing that in the. JM fuel pump,swap instructions. Though there is a lot of "if you have this, do this step, or not" and vice versa, so it's possible I just missed it.

Can someone confirm if I need to drill the regulator in the stock basket assembly with the Aero 340 or not?

Thanks in advance :tup:

The speculation through my fuel pump fiasco is that I probably needed to drill the regulator since I took the black venturi piece out completely and it still did not lower my fuel pressure very much. Since I decided to leave it the way it was and since it probably is not the source of my wobbly idle I ended up putting everything back the way it was... unfortunately all I can offer is speculation =)

I don't have a gauge on it yet since I couldn't fit CJ's tap at the dampener so not sure what psi it is idling at. Actually running around trying to find one locally that will work today.

I was getting spikes/surging when I first started it up with a base tune but that has gone away after Seb revised the tune a couple times. I'm still idling a touch high by maybe 100rpm or so but can't do the Ecutek idle learn with SD tuning, it just doesn't work.

Hopefully I can get a gauge on there today and see where things are at. I suppose that is what will actually dictate if I need to drill the regulator out or not.

What is the target fuel pressure anyhow? I've just assumed it was around 55-60psi...

52psi is stock.

Thanks :tup:

That is a legit question and I need to add that to my fuel pump modification guide.

I overlook it easily because I am, naturally, entirely accustomed to return fuel systems rather than pushing the stock one.

I believe that you will need to drill the stock regulator. Its a delicate procedure since it is not removable, so take great care.

The gauge adapter will fit with the Stillen stuff, but you have to bend the fuel rail inlet tube a few degrees to angle the attachment point a little. I understand that it is very tight on that side of the engine with the new intake manifold and both throttles on that side.

its not that tight. just leave it laying there til you get the intake on and the pipe going to throttle bodies. once all that it installed it just needs a little tweek.

Mine were. Had to push it down pretty hard just to get the silicone coupling on. After that there wasn't room to slide a metal gear clamp between the fuel line and coupling. I'll see how much I can bend the metal tube without kinking it and make some clearance.

What is a good basic Fuel Pressure gauge I can hook up to my stock rails?

CJM Fuel Tap NPT, Nissan 2-Bolt | CJ Motorsports

If you want to go basic just add the optional mini gauge... or use the NPT port to add a sensor for your own gauge.

That looks perfect!... but doesn't seem like it'll work with the damn Stillen Intake Plenum/Intake Charge Pipe. Though in a couple of weeks I'll be switching to TopgunZ's A2A kit.

It does fit the stillen setup but it requires you to tweak/bend the fuel rail inlet tube some degrees to clock the attachment point. Someone sent me pics yesterday I will post.

Yeah, it will fit, but like phunk said you need to twist the hard tube. Which is easily done.

You guys saying it needs to bent even more? Cause I've already bent it as per Stillen's instructions to get the Stillen charge pipe to fit.

You would have to just make adjustment as necessary by examining the exact conflict between 2 components fighting over space. I have not looked over the Stillen instructions but if they dont have you bend it enough to fit the fuel line when raised up an inch, then it would need to be bent more until it did in order to fit this type of spacer.

In the example shown here, the gauge and fitting end up at a bit of an angle. This may be unacceptable if someone wishes for the gauge to point straight forward.

Referencing that picture, I'd have to put a 45 in between the tap and the gauge. I assume that wouldn't be enough to affect an accurate pressure reading hey?

In a perfect world what I'd really like to do is run an 8" line or so from the tap and make a mount for the gauge using the two side by side bolt holes on top of the timing cover for the pressure gauge. Not sure how much that would affect readings or not. Being in the neighbourhood of 60 psi I doubt it would make much difference. Easy enough to do a comparison and test it out I suppose.
http://www.the370z.com/members/chase...6-img-2598.jpg

You can remote mount the gauge and I wouldn't expect the reading to be effected.

Perfect. It this was 6-9 psi like a carb I can see it making a difference but parts jockeys at two different speed shops the other day said it would, so figured I'd find out the actual answer from someone in the know before piecing it together. Darn thing like $100 in fittings hose and gauge just for that little bit lol

I've got a bit of a mess of stuff right in that area though so to even read it easily I need to move it over.

Alright, pulled the trigger and ordered one. Might get here around same time as the A2A kit and I'll just put them on at the same time. The main fouling point seems to be the TB plug, but factoring in height with this thing, might start fouling on the charge pipe. I'll figure something out I hope.

Just did mine the other day, you can bend the hard line enough to fit the tap with the Stillen intake. Just out a pair of pliers or something right at the inlet to the dampener so it doesn't bend right there and you'll be fine.

I added a 1/8" NPT 45* elbow to move the gauge out of the way a bit since I have a bit more going on in that area. Worked like a charm.
http://www.the370z.com/members/chase...6-img-1238.jpg

Now, this OEM regulator. I remember reading earlier that the Stillen instructions were erroneous in saying to use a 7/16 drill bit. Was it supposed to be 7/64... can someone clarify, I'm pulling mine out right now to drill it and get my psi into spec. Thanks :)

Edit: copy of the Stillen instructions
http://www.the370z.com/members/chase...8-img-2817.jpg

According to that instruction image, it says they supplied the drill bits. So you could ignore the incorrect description of 7/16 and use the supplied bit, assuming they didnt actually send you a 7/16 which is almost a half inch diameter and obviously too large.

So I'm installing the S1.SE system in my Z before installing my Boosted Performance turbo kit.

I have a 2016 Nismo and it appears they have updated the stock top hat and wiring. Unfortunately the wiring is different than what's in the fuel pump tech guide.

The fuel temp sensor has two yellow wires instead of a yellow and black so the two black wires aren't together like the guide shows.

https://i.imgur.com/JZHB9GRl.jpg
https://i.imgur.com/05S4vJal.jpg

I do have the DW fuel relay kit. Are there any install instructions or wiring guide for this other than the universal instructions from Deatschewerks?

So I assume I'm only supposed to use the sensor wires from the stock wiring harness? Is there a diagram showing what colors do what on the stock external connector? Mine looks totally different than whats in the guide.

https://i.imgur.com/y8mVVvIl.jpghttps://i.imgur.com/1798mxql.jpg

I have seen those before. You wont need to do much differently with the wiring. You have 6 wires and our connector has 6 positions... so you will just use all 6 rather than only 5 like the older hat connectors.

We can trace each wire with your pictures.

Bottom side:
Black & Blue = Fuel Pump
Red & Black = Level Sensor
Yellow & Yellow = Temp Sensor

If you look at the connector for the top side, you can discover the purpose of each individual wire by flipping over the hat and seeing where each one comes out on the bottom. In your pics we can see that

Top Side:
Pink & Black = Fuel Pump
Yellow & White = Level Sensor
Black & Red = Temp Sensor

You can crimp the terminals and connect each wire coordinating the same as the stock connector and its all set to go. I would recommend using a multi-meter continuity test function to verify each relationship... but the pics make it appear easy to tell which is which.

Just for reference, polarity on the sensors is of no consequence. It only matters for the pump. But may as well match up the polarity too. So again, if you look at the top connector.. the pink wire comes in, and then comes out the bottom as a blue wire. So with the new connector kit, you will do the same thing... pink on top leads to blue on bottom. And then move over to the next wire (heavier gauge black goes in top, comes out bottom as heavier gauge black), and so fourth, until all 6 are done.

For wiring the Relay Kit.. skip the stock fuel pump connectors ground and ground the fuel pump to chassis (using the small skimpy stock ground defeats the purpose of using a relay kit on the power side). Use the relay kit's instructions for connecting the power side to the pump connector... which means you will use the Pink wire in the stock top-side connector to activate the relay in the relay kit.