427 engine (part 2) - RHS block

[Rich Z]

Here'e the Aeromotive fuel pressure regulator that is on my car:

Now here's a pic of what I believe is the same one from Aeromotive's website.

The obvious difference is that silver colored vacuum nipple coming off from the right hand side....

So I went and took a closer look at mine to see what I had there (or HADN'T there, in this case):

Hmm, not only is there nothing on the vacuum nipple, but the nipple itself is gone. Now I have to figure out if I NEED to have that vacuum line hooked up or not for the regulator to function properly.

While I was at it, I took some photos of the connectors on the fuel lines that I have to relocate.

Here's the bundle of lines at the stock fuel pump:

And here's the specific line that I need to change from the AN-06 line that is now on it to the AN-08 line that will come from the out side of the Aeromotive pump:

And here's that AN-08 out line that is on the Aeromotive pump:

Doesn't look like it will be too much of a chore, but I DO need to figure out what to do about the fuel filter issue, since no one apparently thought my car needed one......

 

[Benjamin]

well technically you do have a "filter" at the bottom of the pump in the tank.

The port on the regulator in theory should have a vacuum reference behind the throttle body, when at idle it will pull vacuum and actually lower the fuel pressure a few PSI to help with being rich at idle, then when cruising and there being minimal to no vacuum it will go to normal fuel pressure and then when under boost it will increase 1:1 fuel pressure to boost PSI. at least that is how the ones on the turbo car's I have dealt with in the past have worked. some regulators have a different ratio than the 1:1 but 1:1 is standard unless you go all import and find a 12:1 ratio one.

 

[Rich Z]

Yeah, I've seen pictures of that mesh filter in the tank, so thankfully that probably caught much of the coarser stuff floating around in the gasoline. But I still think I need another fuel filter coming out of the pump. Is a 10 micron TOO small? I've seen all kinds of ones available. I understand that the smaller the mesh the more crap it will filter out, but the drawback is that it will get clogged faster and need more maintenance. Does anyone know how large the openings are in the fuel injectors themselves? I guess the point of this is to keep from clogging the fuel injectors, so that should be the target I need to shoot for. If the injectors are, say, 50 microns, then it doesn't make much sense to try to filter out anything much smaller than that if they will pass through the injector without clogging anyway.

BTW, I was looking over the fuel rail plumbing, and I'm not all the crazy about it. The AN-08 fuel line goes into the back of the passenger side rail, and at the front of that rail becomes an AN-06 line that crosses over to the front of the driver side fuel rail. At that point there is a T junction that has one leg going into the fuel rail, and the other leg going (via an AN-06 line) to the fuel pressure regulator. What worries me is that the driver side fuel rail is a dead end with a plug on the back end of it. I checked, and there just is not enough clearance to put a hose fitting there (not unless I can find one that is no more than 1 inch from the end of the fuel rail to clear the firewall). So I'm thinking that perhaps I need to replace that AN-06 stuff with AN-08 so there will just be more fuel flow to that driver side rail as well as to the regulator. I guess the reason this concerns me is because I've read so many accounts of that #7 cylinder running lean and sometimes breaking pistons. With it being at the far end of that deadend fuel street, I guess I don't want to run the risk of that cylinder getting starved for fuel at any point because it's the last man in line to be served.

Or am I just being a worry wart now? I guess I just don't trust that ANYTHING was done right on my car at this point...

 

[CorvetteJohn]

Rich
I don’t know if this will help you or not but I have learned the hard way about fluid volume. My first house I bought was new and I discovered after the fact that the builder had run all 3/8 copper from the pump to all the fixtures. All the time I lived there if I flushed the toilet and someone was in the shower they were left high and dry so to speak.
My next new house I made sure that it had the same size plumbing as the outlet side of the pump to as close as possible to each fixture then it was reduced to fit the fixture opening. Imagine my disappointment when I had the same water starvation problem as the previous house. In a close inspection I found a 3/8 pinch valve was used in a pipe on the water heater I replaced it with a ¾ gate valve and I can run all my fixtures without any loss of volume.
I think you are on the right track. I would be concerned that one side of the engine has a smaller feed line then the other. My concern would be that one whole side of this beast is running lean.

 

[Rich Z]

Rich
I don’t know if this will help you or not but I have learned the hard way about fluid volume. My first house I bought was new and I discovered after the fact that the builder had run all 3/8 copper from the pump to all the fixtures. All the time I lived there if I flushed the toilet and someone was in the shower they were left high and dry so to speak.
My next new house I made sure that it had the same size plumbing as the outlet side of the pump to as close as possible to each fixture then it was reduced to fit the fixture opening. Imagine my disappointment when I had the same water starvation problem as the previous house. In a close inspection I found a 3/8 pinch valve was used in a pipe on the water heater I replaced it with a ¾ gate valve and I can run all my fixtures without any loss of volume.
I think you are on the right track. I would be concerned that one side of the engine has a smaller feed line then the other. My concern would be that one whole side of this beast is running lean.

Yeah, that's along the same thoughts I am having. Even if I can't find some sort of fitting that would allow me to put that return line on the back of the driver side fuel rail, I'm still planning on replacing that AN-06 stuff with AN-08 to the pressure regulator. I think I can keep the AN-06 return line in place that runs from the regulator back to the fuel tank.

I really don't like the idea of that driver side fuel rail being a dead end leg like it is, but so far I haven't had any luck finding a fitting for the back of it that will let me change it to being a feed THROUGH the rail. It's just REALLY tight back there with not much wiggle room...

Maybe I can find a single driver side rail somewhere and have it machined shorter? :shrug01:

 

[navy2kcoupe]

OR.........find a set of square rails, and drill & tap the side of it :shrug01:.
A fitting coming off of the side would make it easier to do any future
maintenance or mods.......:thumbsup: Just thinking out loud (or more
correctly.....thinking with the keyboard)!
Andy :wavey:

 

[gmjunkie]

Looks to me like that the nipple has been broken out of the pump housing!:thumbsup:

I'd get rid of that pump and pressure regulator and put it back stock with the stock regulator and filter,then go from there!:thumbsup:

 

[CorvetteJohn]

That picture of the fuel rail plug looks to me like when the engine torques up it is scaping the firewall. At least in this pictures I see two witness marks. I wonder if you could use a banjo fitting to get some clearance and also to have a return line from the back of that fuel rail. It would only need to be abel to move the fuel back to the return line so it would not have to be very large in id.

 

[Rich Z]

Looks to me like that the nipple has been broken out of the pump housing!:thumbsup:

I'd get rid of that pump and pressure regulator and put it back stock with the stock regulator and filter,then go from there!:thumbsup:

What nipple is that? I'm not sure of what you are referring to.

Actually, I would like to be able to use as much of the stuff I paid for that I can. So I'm really not inclined to just trash the Aeromotive fuel pressure regulator unless I absolutely have to. Out of curiosity, would the stock filter/regulator support the fuel demands of a 700 rwhp engine?

 

[gmjunkie]

What nipple is that? I'm not sure of what you are referring to.

Actually, I would like to be able to use as much of the stuff I paid for that I can. So I'm really not inclined to just trash the Aeromotive fuel pressure regulator unless I absolutely have to. Out of curiosity, would the stock filter/regulator support the fuel demands of a 700 rwhp engine?

The nipple that looks like it had been screwed in too tight in that hole!

That used to be a threaded hole,Now the treads have been ripped out!
Without a vacuum supply,That regulator is going allow Full Pressure full time!~! The regulator is NOW JUNK!:thumbsup:

I don't know how much volume the stock pumps deliver,But I'll look see if it's in the service manual!

 

[Rich Z]

That picture of the fuel rail plug looks to me like when the engine torques up it is scaping the firewall. At least in this pictures I see two witness marks. I wonder if you could use a banjo fitting to get some clearance and also to have a return line from the back of that fuel rail. It would only need to be abel to move the fuel back to the return line so it would not have to be very large in id.

Right now I'm just looking for ANYTHING that will work. Do you know of any banjo style fitting that would work? I've been pouring over pages and pages of fittings from various websites and just haven't seen anything that looks promising yet.

One of the guys helping me out on CorvetteForum suggested that the current plumbing layout will work OK (not optimal, but just OK), so it wouldn't kill me (nor the engine) to keep it as it is. He didn't comment on the size of the plumbing, but I am planning on going to AN-08 all the way to the regulator, regardless. He did mention that "crud" possibly could accumulate at that "dead head" end of the fuel rail, so I'm trying to figure out the best fuel filtration that I can put in place to keep that "crud" from even getting to the fuel rails.

As for the scraping against the firewall, I presume that happened either at Chris's or Aaron's (or possibly both) when they removed the fuel rail for troubleshooting purposes. The motor mounts are Pfadt polyurethane, so I don't think the engine moves very much at all under torque.

 

[Rich Z]

The nipple that looks like it had been screwed in too tight in that hole!

That used to be a threaded hole,Now the treads have been ripped out!

I don't know how much volume the stock pumps deliver,But I'll look see if it's in the service manual!

Ah, OK. I was told on CorvetteForum that it isn't necessary (nor advised) to use that fitting anyway. The purpose of it is to adjust the fuel flow based on the vacuum line coming from the intake. But since the PCM expects a constant fuel pressure for it's A/F calculations, than having a variable fuel pressure from the regulator would actually CAUSE problems with the tuning of the engine. So it actually is best that it is not being used. Personally, I would like to see that hole just plugged off, rather than being open to the elements, so I may have to see if I can find a set screw or something to plug it off.

Thanks...

 

[gmjunkie]

Ah, OK. I was told on CorvetteForum that it isn't necessary (nor advised) to use that fitting anyway. The purpose of it is to adjust the fuel flow based on the vacuum line coming from the intake. But since the PCM expects a constant fuel pressure for it's A/F calculations, than having a variable fuel pressure from the regulator would actually CAUSE problems with the tuning of the engine. So it actually is best that it is not being used. Personally, I would like to see that hole just plugged off, rather than being open to the elements, so I may have to see if I can find a set screw or something to plug it off.

Thanks...

I guess if you want it running rich at idle and washing down the cylinder walls it would be alright!:shrug01:

 

[Rich Z]

I guess if you want it running rich at idle and washing down the cylinder walls it would be alright!:shrug01:

Explain, please....

 

[Rich Z]

I got the passenger side wheel, brakes, etc. all together with the new half shaft and started taking apart the driver's side. I bought a GM tool to break the shaft loose from the hub and that, along with my spraying the shaft and hub with PB Blaster for the last couple of weeks, got the shaft loose with no issues. I'll get it all apart tomorrow and start cleaning up the various stuff before putting it back together again with the new shaft. Hopefully my rear brakes will still work....

Been talking with a guy from NastyPerformance.com about the fuel system and he's going to be working with me to try to get that all worked out. BTW, he recommended a different fuel pressure regulator, saying that the Aeromotive has been known to be flaky trying to keep a stable fuel pressure.

But in any event, the light at the end of the tunnel is starting to get brighter.... :dancer01:

 

[RevXtreme 1]

Ah, OK. I was told on CorvetteForum that it isn't necessary (nor advised) to use that fitting anyway. The purpose of it is to adjust the fuel flow based on the vacuum line coming from the intake. But since the PCM expects a constant fuel pressure for it's A/F calculations, than having a variable fuel pressure from the regulator would actually CAUSE problems with the tuning of the engine. So it actually is best that it is not being used. Personally, I would like to see that hole just plugged off, rather than being open to the elements, so I may have to see if I can find a set screw or something to plug it off.

Thanks...

Absolutely false....but I'm sure I know nothing as I see some other problems you have decided to ignore also. I'm not sure why you keep getting charmed by those that have only some knowledge or wrong info alltogether, but hey, its your car! :thumbsup:

 

[Rich Z]

Absolutely false....but I'm sure I know nothing as I see some other problems you have decided to ignore also. I'm not sure why you keep getting charmed by those that have only some knowledge or wrong info alltogether, but hey, its your car! :thumbsup:

Well, explain it to me, then, please.

Perhaps my understanding is faulty, but from what I understand the PCM controls the air/fuel ratio at all RPM ranges by controlling the pulse width of the fuel injectors. This pulse width command to the fuel injectors has to assume that the fuel pressure is known, as the amount of fuel needed for a proper air/fuel mixture is ONLY controlled by the duration of time that the fuel injector is commanded to be open. In other words, with a constant 60psi of fuel from the regulated fuel rails to the fuel injectors, if the PCM has been sending out a 20 millisecond pulse to the fuel injector and decides it needs MORE fuel for a proper AFR, it issues a longer firing pulse (like 22 ms). If it needs LESS fuel for a proper AFR, it issues a shorter pulse (like 18 ms). These calculations all HAVE to assume a known and constant fuel pressure, otherwise the desired AFR will be completely at the mercy of whatever the fuel pressure is at any given firing of the fuel injector pulse. A 22 ms at 60 psi will not deliver the same amount of fuel as an 22 ms pulse at 58 psi. So if the PCM commands say an 18 ms pulse because less fuel is warranted for the AFR desired, and the fuel pressure has changed from 60 psi to 62 psi for that commanded 18 ms pulse, will the resulting AFR be what the PCM was trying to achieve?

So with the fuel pressure regulator changing the pressure in the fuel rails via that vacuum line, how does the PCM know what the fuel pressure actually is at any given moment? Is there a fuel pressure sensor somewhere that the PCM references for this variable in it's calculations for the proper AFR to command for each injector firing? I've been looking, and I just don't see one. Not to say that there isn't one that I just haven't found yet, mind you.

What that vacuum line does for the fuel pressure regulator (as far as I have been able to determine) is to reduce fuel pressure at high vacuum, which indicates low engine speed, such as idle. Then on the reverse side, say in a boost condition with positive manifold pressure, the regulator will increase the fuel pressure on a 1:1 ratio.

So with all the above in mind, how does the PCM know how to accurately command the AFR that it calculates as being optimum when the CONSTANT it expects from the actual fuel pressure varies with what the fuel pressure regulator is doing with fuel pressure?

I hope this doesn't come across as argumentative, as I am trying to filter everything anyone suggests to me by everything else I am told and what I am learning from every possible source I can find in this process. I just am not taking ANYONE or ANYTHING at face value any longer without researching what I am being told to do. If I understand something incorrectly, then please SHOW me where I am wrong about what I think I know. Sorry, but I'm just not buying ANYONE telling me to "Do it this way, trust me". I've already trusted two shops far more than I should have, and look where that has gotten me...

So, if the PCM can, in fact, determine actual fuel pressure somehow, then yes, I will buy the fact that a fluctuating fuel pressure from the fuel pressure regulator via that vacuum line is OK to work with. But if, in fact, the PCM EXPECTS a constant fuel pressure at the fuel rails, then I'm sorry, but then that vacuum line to the fuel pressure regulator does NOT make sense to me because of the above stated reasons.

 

[Rich Z]

And while I am thinking of this, can anyone tell me if the stock fuel filter/regulator has a similar in function vacuum line running to it?

I sure didn't see one......

 

[CorvetteJohn]

Banjop fittings

I have tried in vane to find a chart that gives the diemensions of the banjo but can not find one. Looking at the picture again it looks like there is an adapter in the fuel rail so they could put in a plug. You might try removing the plug and the adapter and going to a hyd hose supplier and see if they have a banjo fitting that would go directly into the fuel rail without the adaptor. That might get you the clearace you need.

 

[Rich Z]

Thanks for looking for me. I've also been looking and asking around, with no luck. Nate at NastyPerformance suggested that I may just have to bite the bullet and cut the firewall, as it actually would be best to have flow all the way through the fuel rails. Which my gut feeling agrees with, but was hoping I wouldn't have to butcher anything else on the car in order to accomplish that. If I HAVE to go that route, I'm thinking a 180 degree fitting will give me the least amount of cutting I will have to do to the firewall to clear it. If I put in a 90 degree, then the fitting for the hose will be hitting back there, and I would have to remove more firewall to clear it. Maybe I'll see if there is something like a 120 degree fitting. That might give me a better angle for that braided hose plus keep the fitting clear of the firewall. Otherwise if I go with a 180, I would likely use another 90 degree on the end of that 180 to point the hose toward the regulator.

I'll still have to cut enough of the firewall away to keep the fuel rail and/or hose fitting from hitting the firewall from movement of the engine under torque, though. Things would get REAL messy in a hurry having a fuel rail fitting BREAK OFF while under WOT conditions....

While I'm thinking of it, I guess I could always try to form an aluminum panel for that hole so it just doesn't look like a gaping hole in the firewall. I would like it to at least LOOK like a professional job.