36 replies to this topic

[FTodaro]

I'll add I've never seen an nb hold pressure for long. Aka drops at shut off and soon after it is 0
And I've seen a few

For the record, i was talking about an NB, not an NA. My experience is the same as Chris's.

[Johnny D]

https://www.youtube....h?v=RmwqnqL3Hbg

J~

[chris haldeman]

Johnny you are special😜

[Johnny D]

https://www.youtube....h?v=Hy5wNeSPzfQ

J~

[RazerX]

Jamz,

 

Last November, i had injectors cleaned and balanced, new o rings and injector seals.  I am 99% sure it is the pump.  I have an A/F in the car and it is as consistent as changing environmental variables allow.  It is always within a couple tenths of what i expect when running.  So I recall there is a check / return valve on the pump as I think there was a video of the NB pumps and little plastic bits that fail and some mention that then can not hold pressure but still pump.  

 

FWIW, I have the older AA regulator in the engine bay.  I would love to hear an engineer explain why the one on the trunk (w/ 10 feet of head loss) is superior to the one close to the fuel rail....

[Johnny D]

Here David, it's in the store ^^ 99~05, more people should look around up there. (the pic of the return line mod are there as well)

This regulator is engineered to work the same way Mazda designed the original system to work. With one regulator, with a return back to the tank. This ensures proper regulation of fuel pressure/pulse to the fuel injectors. Other products on the market piggy back a second regulator that does not return excess pressure to the tank but bleeds it off with the injectors opening and closing. This can cause an uneven pressure and pulse that the injectors can see, which can lead to fluctuating A/F ratios. In addition, regulating the fuel pressure by constricting the orifice size is tuning on the razors edge. You are limiting both the volume as well as the pressure of fuel supplied to the engine. This system does not limit the volume of the fuel, just the pressure it is delivered at. A large fluctuation of temperature when using "other products on the market" can lead to an extreme lean condition which can have catastrophic results, usually ending with an engine failure.
This kit is made to the highest standards using AN 6 and OE quick disconnect hardware. No hose clamps are used in this system at all. There is also no cutting or modifying of the OE hoses. All hoses are professionally made custom for the application and crimped to the fittings. The regulator is made by the leading manufacturer of fuel systems. This kit comprises all the best parts possible. Don't be fooled by cheaper inferior products on the market.
Our regulator is mounted in the trunk and not in the engine compartment. By mounting the kit in the trunk we keep it away from the heat of the engine compartment which can effect the temperature.
Adjustment is simple with one screw and the kit comes with a liquid filled gauge to monitor your pressure. There is also an additional un-used port on the regulator which can be used to add the optional fuel test port kit fitting.
Monitoring and tuning your AF ratio can help get the most performance out of your engine. This is the kit to have.
This kit comes complete with the following items:
• Adjustable Fuel Pressure Regulator
• Professionally made custom fuel lines (2)
• Instructions
• Liquid Filled Gauge
• Replacement Fuel Line

J~

[RazerX]

Here David, it's in the store ^^ 99~05, more people should look around up there. (the pic of the return line mod are there as well)

This regulator is engineered to work the same way Mazda designed the original system to work. With one regulator, with a return back to the tank. This ensures proper regulation of fuel pressure/pulse to the fuel injectors. Other products on the market piggy back a second regulator that does not return excess pressure to the tank but bleeds it off with the injectors opening and closing. This can cause an uneven pressure and pulse that the injectors can see, which can lead to fluctuating A/F ratios. In addition, regulating the fuel pressure by constricting the orifice size is tuning on the razors edge. You are limiting both the volume as well as the pressure of fuel supplied to the engine. This system does not limit the volume of the fuel, just the pressure it is delivered at. A large fluctuation of temperature when using "other products on the market" can lead to an extreme lean condition which can have catastrophic results, usually ending with an engine failure.
This kit is made to the highest standards using AN 6 and OE quick disconnect hardware. No hose clamps are used in this system at all. There is also no cutting or modifying of the OE hoses. All hoses are professionally made custom for the application and crimped to the fittings. The regulator is made by the leading manufacturer of fuel systems. This kit comprises all the best parts possible. Don't be fooled by cheaper inferior products on the market.
Our regulator is mounted in the trunk and not in the engine compartment. By mounting the kit in the trunk we keep it away from the heat of the engine compartment which can effect the temperature.
Adjustment is simple with one screw and the kit comes with a liquid filled gauge to monitor your pressure. There is also an additional un-used port on the regulator which can be used to add the optional fuel test port kit fitting.
Monitoring and tuning your AF ratio can help get the most performance out of your engine. This is the kit to have.
This kit comes complete with the following items:
• Adjustable Fuel Pressure Regulator
• Professionally made custom fuel lines (2)
• Instructions
• Liquid Filled Gauge
• Replacement Fuel Line

J~

Hi Johnny,

 

I have a seen that document and I am working to separate the marketing from the engineering.

The description opens by implying value of the OEM setup, then changes it to a bypass system with a return line.  Additionally the OEM uses this ‘razor’s edge’ of an orifice to manage fuel pressure, and as does this system, as does the one Advanced Autosports sells.  They all have a AFPR that works roughly the same regardless of where  it is.  They both still have the regulator / pulse damper prior to fuel rail and both use Aeromotive AFPR, so that gets  â€˜marketing’ BS meter active.  While we can argue if the trunk gets hot with an exhaust pipe under it and no circulation.  We are likely talking more about the density of the fuel changing than the orifice hole changing much with a delta temp.   Not to mention that the flow of the fuel is likely a far bigger influence on the orifice temp, that the sounding temps.  I have felt that engine mounted AFPR and not once has it be ‘warm’ like many other engine compartment bits.  Usually feels cool relatively speaking. 

But there is an argument for it in the engine bay, it is very close to the injectors, and thus the variance is smaller from the AFPR, than all the way back in the truck.  In this solution you set the pressure in truck, but it is subject to head loss from AFPR all the way under the car to the regulator.  If there is argument being made about temperature and orifices then surely you have to consider this as well.  Headloss is also affected by fluid density.  True that gas is really not compressible but having a higher pressure at the engine bay mounted AFPR means that when you go from low to WOT, that proximity could mean even less of a chance of lean situation.  That is a weak assert to be sure but can’t be worse than one in the trunk.

So clearly I may be missing something but if I simplified to the pure difference this is what I see and for the sake of argument the brand and type of AFPR is the same.

Trunk AFPR mounted converts to return line orientation and provide a target pressure from the trunk to the engine bay where it is still managed/dampened by the regulator before the injectors.

Engine Bay AFPR maintain OEM configuration but adds a AFPR in line that restricts pressure from that point to dampener/regulator prior to the injectors. 

So the question is one really better than the other?  If so how?  I mean really how?  The trunk has had some reported issues if the return run is not properly running on the pick-up sock that they can ‘hiccup’ earlier than the OEM setup.  The trunk job is more complicated.  Gauge in the engine bay on the regulator is more convenient for one man troubleshooting.   But it is nicer to the extra space in the engine bay.  

 

I am just asking.  I am engineer, and always willing to learn, but engineers also have a right to blow the BS whistle and look for facts and data.  

[Johnny D]

Just saying.

The guy selling it seems to win a lot.

 

Also, you can lead a horse to water...

YMMV, etc, etc.

J~

[chris haldeman]

Another interesting point... The seller of the underhood mounted reg no longer sells them for the 99 up cars and has switched too a very clean rear mounted design

[Johnny D]

Hi Johnny,
 
I am just asking.  I am engineer, and always willing to learn, but engineers also have a right to blow the BS whistle and look for facts and data.

Being an engineer and all.
Is it blow the whistle and then look for the facts and data?
or
Look for the facts an data and possibly blow the whistle based on the results.

J~

[Steve Scheifler]

Perhaps you interpret "blow the whistle" different than he meant it. He makes perfectly valid points and asks reasonable questions. If people who designed the trunc systems are certain that it is a better system, then surely they can answer his questions and help all of us to understand.

[Johnny D]

You could be right.
I just don't look at something and say BS until proven, sure do Missouri, "show me".
 
This isn't my opinion below, this was a cut and paste from the description of the FPR.
 

This regulator is engineered to work the same way Mazda designed the original system to work. With one regulator, with a return back to the tank. This ensures proper regulation of fuel pressure/pulse to the fuel injectors. Other products on the market piggy back a second regulator that does not return excess pressure to the tank but bleeds it off with the injectors opening and closing. This can cause an uneven pressure and pulse that the injectors can see, which can lead to fluctuating A/F ratios. In addition, regulating the fuel pressure by constricting the orifice size is tuning on the razors edge. You are limiting both the volume as well as the pressure of fuel supplied to the engine. This system does not limit the volume of the fuel, just the pressure it is delivered at. A large fluctuation of temperature when using "other products on the market" can lead to an extreme lean condition which can have catastrophic results, usually ending with an engine failure.
J~

Then the post that his FPR has been discontinued and the new one is similar to this one ^^.
IDK, I've been wrong before.

J~

[RazerX]

My BS meter, like spidy sense tingles.  I am not saying it is BS.  I am just saying that to me and my understanding I have some doubts about how some of the statements are said and I am seeking knowledge.  And I explained why I think the benefits may be the same.   In my brother's car that I help him build he put it in the back so I am not against it.  Just wondering out loud which is better and why.

 

Beta lost out VHS and there many other situations where popularity and marketing have one product triumph over a comparable or even better product.  More bits and bobbles needed w/ the trunk one, maybe a better profit margin?

[davew]

I may not be an expert, but I did spend a night at Holiday Inn Express.

 

I designed the first AFPR for Spec Miata. Mine was the prototype system that the SMAC tested prior to approving it and the slotted timing wheel. Way back in the olden days.

 

If I had my choice for an NB, I would use the under hood mounted design. I built the first regulator using this method and sold a bunch of them. This design does not use an Aeromotive built regulator. All Aeromotive regulators are a return system design. In other words it sends the extra fuel back to the tank. The NB does not have a return line from the engine back to the tank. It is all done at the rear of the car. The regulator I used was a non-return style regulator. A hi pressure version of the little chrome unit we have been using forever on carburetor cars. Also similar in function to a gas regulator used on a welder. Unfortunately the manufacturer discontinued the regulator. I had a final batch made, but those are all gone. To my knowledge, and believe me I looked, nobody makes a fuel injection, non-return regulator. I ran a fuel pressure sensor to my data system at hi-resolution and found the pressure never varied more than 1/4 of a pound. The system installed easy. In about 10 minutes.

 

Since I have not been able to find a new source for the regulator, I went back to the drawing board and made what "I" feel is an improved version of what others where selling. But that is a different story. I am using a competitor of Aeromotive for my version. Works the same, but I like this company better for this application. I will state that for my NA version, I use an Aeromotive regulator. I sold several hundred of the under hood versions. I never had anyone call me and say their engine failed because of lack of fuel. Let's face it, the fuel rail gets hotter than the frame rail.

 

The trunk mounted version is more expensive to build, and harder to install. A couple hours versus a few minutes. Both do the same job in a different way. I do not feel either works better than the other. But, unless I go in the regulator manufacturing business, we are all stuck with the trunk mounted version. If you can find a 70psi, non-return regulator, let me know.

 

I hope this explains better

dave

[FTodaro]

I do not know if I am getting us off the topic or back on

 

Question what does the fuel pump relay do?

 

Where is it?

 

Is it different for the 99,00, and 01?

 

when it goes bad what are the symptoms?

 

experts non experts or just folks sleeping at a holiday inn what is the story?

[Johnny D]

Does this help Frank ?
http://www.miata.net...lter/index.html

J~

[Steve Scheifler]

Excellent Dave, thanks for the explanation. It makes sense and paints a different and more logical picture than some seemed to infer and/or imply.