Thanks Charles I will do that this weekend. I did a quick test after driving the car last night I turned the car off with the key on and pulled the fuse to see how fast the pressure would drop. It would go from 58-60PSI down to 0-5 in less than 4 seconds.

IM assuming its supposed to hold pressure much longer than that?

Generally it takes much longer than that, but with aftermarket regulators it can be unpredictable. They do not make it a design intention to hold pressure when the engine is off, its just a side effect that they do... and they are all sort of individuals.

But most will take a lot longer than that to fall so low.

Got it figured, the regulator delete was leaking, but only at about 40+psi. We swapped out the oring and so far so good. I did notice that when clamping down the regulator I could push it down and bottom it out, which leads me to believe that the spacer used above that oring could be a tad bit thicker to squeeze that oring in there a bit better.

If it starts to leak again then ill probably get a shim to put in there to squeeze that oring in its housing.

Thanks for the info Charles, you were bang on, now the car feels quick again. Has no issues holding 70PSI.

Excellent news! Good job Mitch!

Going to take it to the track tomorrow night and see what she can do now that I can bump up the boost without going lean again.
:D im either going to come back with a good trap speed, or a popped engine. lol

You have the replacement standing by or you still contemplating the build?

If possible I would like to get as much information on why it was leaking as possible so that I can determine if the part should be updated of it it was just a basic o-ring problem. We do have lots of them out there but that doesnt mean there isnt potential for slight inconsistencies in manufacturing of either our component or the factory housing that it secures to.

Do you believe it was the bottom o-ring that was leaking, which is the one we supply that gets squeezed when you tighten the 2 small bolts? This I believe would be the one most prone to a leak of the 2 o-rings. The factory o-ring and spacer reused from the factory regulator which seal on the sides rather than vertical will be less susceptible to leaks.

Please feel free to post or PM me any information or if you think a change to the part would have made the difference let me know.

Awesome Charles. Here is some more info..

When I pressurized the feed line it was good until about 40PSI then I started to hear air seeping by what seemed like the back side (side closed to the can) of that regulator. When I took it apart it appears that there is a almost like a keyway in the back side where that regulator slides in. That is where it appeared to be leaking by the upper oring.

I replaced that oring (which I felt was a bit soft, maybe the fuel additives I am using was eating it?) with a new one and she easily held 50-60psi. When putting the clamp back on I was able to bottom out the regulator on its mating surface, which to me implies that there is not very much overall clamping force being applied to that oring to being with. I felt if that stock shim that we use was just a tad bit thicker this would put more pressure on that oring and create a better seal.

Time will tell if I blow that seal out again, I am probably running a higher fuel psi than most guys I would imagine. The regulator is set to 58PSI with the boost reference hooked up to boost only. If I do pop it I will see about getting a shim to fit in there.

Thanks!

Mitch

The keyway you describe is where fuel bleeds from the filter housing to the inlet of the regulator.

The regulator delete fitting crushes the smaller lower oring when its seated and tightened down. But it is not supposed to crush the larger top oring vertically. That oring seals by the pressure applied to its sidewalls between the housing and the delete fitting, which is also how it sealed to the factory regulator.

I am surprised it was your upper oring that was leaking. An upper oring leak would allow pressure to leak externally. A lower oring leak would allow pressure to leak into the return channels.

So to clarify, you replaced the factory o-ring and the problem was solved, and kept the same o-ring that we supplied?

Makes sense, this lower oring then could stand to be just a tad bit thicker (mind you its probably just squished down from being installed for a year already. In which case there is not much you could do anyways.

The upper oring seemed soft to me, I replaced it with a new one that felt more rigid but yes it was the exact same one. If I had one just a touch bigger I probably would have used that one, but the next size up was much to big to work.

I dunno Charles, I think mine was probably just a fluke and the fact that I am running north of 70psi at times might just be to much for the system to hold. Do you suggest I turn it down and retune?

Also I noticed that the regulator pressure drops about 4psi when it heats up. Aeromotive says to set the regulator cold, is that what you suggest? Just seems like a pretty good drop when it heats up. Also many of the tuning books I have say to connect the 1:1 line to a vac/boost source, I currently have mine connected to a boost only. Should I switch it? I would assume you said a boost only source on this particular car because of the vvel messing with the idle and thus the vacuum around idle.

Back to having issues while on the dyno.. I just cant win with this mess.

Ive checked everything, while cold the system is fine, as it heats up the pressure drops to levels that cause lean conditions under WOT. I have started looking to see what the GTR guys are doing.

Something has to be wrong with my intank setup, I mean no one else has any issues at all. Charles, would you entertain me purchasing a new basket with all the mods done by you so that would rule out anything wrong with my intank setup.

I checked my leak down pressure and the car has no issues holding pressure after the pump is unplugged now, which rules out internal leaks I would think. I did hit ~500rwhp on the dyno before the car started to act up. :) so that is a plus but had to stop afterwords because she started really leaning out.

Ughhhh.

Try doing my level 2 fuel pump modifications which bypass the internal filter entirely. This would eliminate potential leaks at the o-rings or backed up internal filter. This will require adding an external filter inline somewhere though.

It could very well still be leaking at the orings, everytime I pull it apart I find what I assume to be oring rubber in the basket. Maybe I am just asking for to much pressure and when it gets hot and the orings get soft it blows them out.

Hard part is in order to bypass that filter I will have to cut that factory line and replace it with fuel hose which means going back to the stock configuration could be an issue.

Would you entertain the idea of building me a basket with the required mods?

Mitch.. I mean no one else has any issues at all. WHAT..! :confused:

I am trying to work somethings out myself too, I believe it's part of being a Z owner, I only wish I had taking Auto 20/30 in high school. And I am kicking myself for it now. Hang in there Mitch - but have you considered Zat Zuma's Dual Fuel pump for sale? I think he still might have it. Hope you work it out.

What issues are you having? Same thing?

Just bought a whole basket and I am going to put my engineering degree to use and try and modify my current one to see what I can come up with lol. (I am sure anyone who works with an engineer will be rolling their eye nows, haha)

I will either wreck it or fix my issue. Ill grab some pictures of what I come up with. Now that I have another basket on the way I am not scared to modify mine past repair.

Hey man if you are looking for a solution, I have a Fast Intentions Fast 500 system that was made to resolve that issue. PM me if you are interested.

Sent from my SM-N910P using Tapatalk

I am not sure what the rubber that gets in the basket is from, but its not the orings. I get that same rubber and the ones that have been sent in to me get it also. The orings are Viton and will not degrade. If you replaced an oring with one of your own, its possible that you didnt use a fuel-safe material.

I would gladly assemble a fuel pump module for you and pressure test it before sending out.

In fact, send me the one you are having a problem with, and I will test it as is and tell you if there is anything wrong with it. Turn around time one day, and I will ship it back no charge. I am interested in seeing this for myself for if there is something wrong with it, it will just be something for me to watch out for and help others with.

Remove the level sensor before shipping it, those are fragile and I of course wont need that here.

are you also having problems with a fuel pump or fuel pressure?

I would take you up on the offer if my car wasn't currently strapped to the dyno. Id love to send it to you but I think I will just try to modify this one myself since I have another one coming in a week or so. I cant imagine I am doing anything wrong as I can apply 50psi of air to the outlet port and she holds, and I can confirm that when I shut off the car it holds fuel pressure with no issues (after fixing that oring). I am going to do what you said and bypass the basket filter and put a inline filter in the car. So it will go straight from the pump through a inline filter and to the engine, then back in through the venturi setup. I am going to try and remove the factory filter from the basket to allow for more fuel to sit in the basket.

I just went out and bought all the parts to do this, if I didn't want my car for the weekend I would have sent you it. If I do this and its still dropping off then my next place to look is the wiring, which could be the issue with the repeated higher pressures that the 1:1 regulator puts the pump under. I am also going to turn down my pressure since I am only hitting ~60% duty on my injectors so far.

Ill take some pictures, and you can see (in horror probably, lol) the mess I am going to make to try and fix these issues haha. If this works then ill have another basket to maybe try and see if I can fit it in the other side and have another pump T into the outlet inside the tank and run 2 pumps (one from each side) in parallel together. This would also act as a transfer I would think. But thats in the future.

I do appreciate all your input Charles, if you dont mind what is your baseline pressure set at?

If your basket holds pressure, than it can only be a couple things causing pressure to drop:

1: filter clogged
2: fuel pump output too low (out of steam, defective) or wiring for it is not keeping up.
3: regulator bad
4: out-running the feed plumbing on the car, pressure dropping at high demand

I always ran a static pressure of 52-53psi in my car, no vacuum/boost reference.

1. Filter could be clogged, but this would not explain why drop only occurs after repeated pulls.

2. Wiring does make sense, maybe repeated pulls heatsoak the wiring and as such the current and heat spiral out of of control (more heat, causes more current, which in turn causes more heat).

3. Doesn't explain why at the start of the pulls its perfect, 0 issues. Unless it is sensitive to engine bay heat, but I called automotive and they said they chances of it being the regulator are slim to none.

4. Also doesnt explain why its perfect when the pulls are starting. Ill get 2-5 pulls then she will start to really suffer.


My wife was looking through some R35 forums and one guy had a weak battery cause these issues, well mine is still the stock battery, so I think I will change that out as well as put more effort into tracing and diagnosing the wiring. Maybe I should go back to a static pressure in efforts of relieving the stress on the fuel pump wiring.

Call me, its my fuel issues ALL over again

PM me your number I didnt save it anywhere.

Thanks Lloyd.

What was the fix?

BTW, you are still running the factory EVAP system right? If you are getting a vacuum in the tank, that can cause a big fuel pressure problem once the car has been running for a little while and builds up a big vacuum in the tank.

I thought about that last night, so I shut everything off and listened for a suction when I opened the tank and there was none. I could try doing a few pulls with the lid off to see what happens tho, ill add that to the list of things to try.

My car is doing something similar but when it seat overnight. When i turn the car cold it struggles for 4-5 seconds on the 1st try. Ones the car heat up no matter how many times i start the car during the day it fires right up. I upgraded the walbro 255 to a aeromotive 340 and 1000cc injectors. Before that i never had any problem before the upgrades.

I took off the boost ref line today, set my regulator to 55psi and its been working perfect. I think the added pressure was causing to much of a current draw and heating up my wiring. Ill know for sure when I finalize the tuning tomorrow hopefully. But even down to a 1/4 tank she would only drop to about 52psi under wot.


I think you might have one of the issues I was having. Do you have a way to watch fuel pressure? If you do, turn the key on let the system pressure up then kill the fuel pump and watch the pressure, it should slowly bleed. If it dumps all at once then you know you have a internal leak inside the basket. That said if you have a return type system a good practice is to turn the key on, wait 2-3 seconds for the pump to build up pressure then crank. If you go straight to cranking you have to wait for the pump to work up the pressure. Alternatively it could be tuning, in ECUtek there is fuel tables for cranking that may have to be adjusted. That said if your tuner dialed in the injectors correctly they they shouldnt have to touch them, I didnt but I am only at 750s.

Thanks for the tip man. I do have CJM Return Fuel System. When i got the car back from the upgrades and tune the car work perfectly for 3 days after that it started acting up when cold and it was really bad. The car struggle after trying to crank 7-8 times then it would fire up. My tuner adjusted the fuel tables but still it does it but now is just after the 1st cranking that the car has difficulty to start. Plus now the damn car is throwing p2101 which is the throttle body on the passenger side which is just great:shakes head: I'll be taking the car back to the shop to have it look at and do what you said. Thanks :tiphat:

The black gunk plugging the pre filter is the fuel hose breaking down. For some reason if the clamps are tightened too tight and the hose is cut, it decomposes.
Once I replaced the fuel hose, the black gunk never appeared again.
GTM kit btw.

Once that happens the black gunk plugs the basket fill orifice's and it wont run right again. Fuel pressure goes low at high fuel demand. That is as far as I got. Returned the car to stock and replaced the fuel pump with a stock one.

That's my educated guess based on my experience.

That could all make sense. What fuel hose did you replace? All the hose in the tank is the hard plastic type. Everytime I do pull apart that basket there is that gunk in the bottom, I assumed it was a result of the orings.

Also I ran into a low pressure condition again, just when I think its all good I get a nice shot of 30psi during a wot pull, its downright dangerous, thank god for ecuteks good knock strategy protection.

Hoses from the fuel pump that came with the hose clamps

The two short pieces that make up the U that feeds the intank filter?

Yup replaced them and viola ..... no more black gunk chunks

What did you replace them with? Just more fuel hose?

I used the specialty fuel resistant hose that Phunk uses and didn't over tighten the hose clamps. No more gunk.

So first nice day here where temps were around 70F and the stupid car can not even make enough fuel pressure out of boost. It drops down to the 20s as the car starts to get going and building boost.

When you guys set your regulators do you see the fuel pressure change? When I left the house this morning with a cold car the pressure was ~60psi with the car running. Right now as it sits it barely makes 50 with the car off. Is it common for a regulator to fluctuate that badly? Regulator is warm but not hot to the touch. I redid the wiring around the relay and I can 100% confirm that the wiring is not hot, again relay is warm but I can hold it in my hand without it burning.

I also confirmed no leaks internally in the tank anymore because the car has no issues holding ~40psi when you turn the car off.

This is very frustrating. I guess its time to get a new regulator to test it out. Its the last thing left.

If you have a vacuum line connected to the regulator, the pressure will be all over the place as idle vacuum can change a bit. But if its tuned with a static fuel pressure and no vacuum line, than you shouldnt see any noticeable differences in fuel pressure.

No vac line is connected.

Cold start sits at ~56-58psi, when hot its about 46-48psi.

Would this be a regulator issue possibly then? Ill get another regulator and try that tomorrow hopefully.