Anatomy of a Fuel Bucket

[b727pic]

With all the talk of Fuel Systems lately, thought I would tear into my spare tank and see what is what, so here goes......

http://i5.photobucket.com/albums/y183/conibell/Fue l%20System/FuelBucket3.jpg

Knock the retaining ring loose.....kind of like the Jack in the box toy!! Boiiinnggg
http://i5.photobucket.com/albums/y183/conibell/Fue l%20System/FuelBucket8.jpg


Hmmmmm what do we have here?????
http://i5.photobucket.com/albums/y183/conibell/Fue l%20System/FuelBucket10.jpg

Out of the tank.....lets tear it apart!!
http://i5.photobucket.com/albums/y183/conibell/Fue l%20System/FuelBucket11.jpg

After a little prying, the lower bucket is removed.
http://i5.photobucket.com/albums/y183/conibell/Fue l%20System/FuelBucket16.jpg

Here is the upper assembly, with the pump and all the goodies attached.
http://i5.photobucket.com/albums/y183/conibell/Fue l%20System/FuelBucket19.jpg

My uneducated guess as to how this works.
Fuel is picked up by the pump through the strainer and delivered to the upper whilte housing, then under pressure there are two ports, one delivers fuel to the engine, the other ports fuel to the bottom of the bucket to the venturi system
http://i5.photobucket.com/albums/y183/conibell/Fue l%20System/FuelBuckethowitworks.jpg

Fuel pump removal from upper housing
http://i5.photobucket.com/albums/y183/conibell/Fue l%20System/FuelBucket28.jpg

Tiny little bugger...
http://i5.photobucket.com/albums/y183/conibell/Fue l%20System/FuelPump2.jpg
http://i5.photobucket.com/albums/y183/conibell/Fue l%20System/FuelPump1.jpg

[b727pic]

for discussion purposes, I have set the pump and the manifold into the lower bucket. you can see where the manifold is set into a molded receptacle which directs high pressure fuel into what I call a fuel eductor
http://i5.photobucket.com/albums/y183/conibell/Fue l%20System/FuelBucket37.jpg

Empty lower bucket to compare with above, note check valve on lower LH side
http://i5.photobucket.com/albums/y183/conibell/Fue l%20System/FuelBucket35.jpg


Here is the outside of the fuel pickup point for the bucket, High pressure fuel is directed from the manifold inside through a larger and slightly beveled hole in the bottom of the bucket. this essentially is a jet pump, the high pressure stream creates a negative pressure area around the inlet which draws in surrounding fuel.
http://i5.photobucket.com/albums/y183/conibell/Fue l%20System/FuelBucketventurishown.jpg

For a briefing on Jet pumps, motive flow, eductors and such: http://www.kinetic-therm.com/english/product/ejec-thermo-vac/page01.htm

[AnoxieGTO]

interesting...

[CSiJason]

I'm wondering why the complex waste of plasic and not just a larger more capable fuel pump?

[rcpepper]

Probably because of the returnless fuel system. Looks like the fuel pressure regulator in the picture of the empty bucket.

Rob

[b727pic]

This thread shows the "cut a bucket" approach.
http://www.exoticperformanceplus.com/services.php? service=59

I really don't see how cutting the holes is going to interfere with the venturi system. However I am not totally sure how the holes actually enhance the buckets ability to fill either. This whole bucket assembly is under spring tension between the top and bottom of the tank. The bottom of the bucket sits flush against the bottom of the tank...again under tension. While its not a perfect seal, I fail to see how the large holes are augmenting the filling of the bucket.

Any comments from those who have gone down this path would be welcomed at this point.

As for me, a little more thought.......plus I have to go to work:o

[wraith]

I would think the holes in the bucket just allow more fuel to keep it full in case the pump draws in fuel too slow through the screen, but I dont see how its possible to draw in fuel slower then it pushes out to the engine unless your trying to decrease the pressure loss by bypassing the screen.

Sam

[TrakDay]

B727... I am working on a few things right now and in the near future depending on my situation I may be interested in buying that stock fuel pump/regulator from you to do some testing/use of my own. Just let me know if you might be interested in letting it go. I may not even need it, but I will know fairly soon...

[b727pic]

I would think the holes in the bucket just allow more fuel to keep it full in case the pump draws in fuel too slow through the screen, but I dont see how its possible to draw in fuel slower then it pushes out to the engine unless your trying to decrease the pressure loss by bypassing the screen.

Sam

Keep in mind that the holes are covered by the bottom of the tank.....go to the link that shows the holes in the bucket, now imagine a piece of steel covering those up on the bottom....you are somewhat defeating the purpose of cutting the holes in the first place.

As stated its not a perfect seal, so maybe that is all it takes???????

[MadGoat]

I'd br interested to see what the difference is on the 05 setups causing the fuel problems.

[b727pic]

I'd br interested to see what the difference is on the 05 setups causing the fuel problems.

According to AC Delco PN MU1371 is applicable to:

2006
2005
2004

GTO's

IMO it just means you 6.0 guys are 50HP closer to running out of fuel before us 04 guys!!:gr_jest:

[bullygoat]

Empty lower bucket to compare with above, note check valve on lower LH side
http://i5.photobucket.com/albums/y183/conibell/Fue l%20System/FuelBucket35.jpg


I think if you could find a way to add another one of those check valves to the lower half of the bucket, you will be taking a huge step in the correct direction. You'll notice how low it is. It's the main source for fuel to enter the bottom of the bucket for the fuel pump to pick up. The venturi also does this, but if you can't get fuel to even prime the pump, it's worthless. Adding another hole with a check valve, will allow the bucket to fill and stay filled because the check valve will close off holding fuel, unlike the cut-a-bucket design.

Just my .05(damn taxes)

Tim

[b727pic]

thanks to DDawson for the pic, this is an 8.1L Bucket, not sure of the venturi system differences, but easily seen is the addition of a couple one way check valves on the bottom of the bucket. Also note the bottom of the bucket has small stand off's to raise it off the bottom of the tank somewhat, and the check valves are inset as well.
......................................8.1L........ .................................................. .................................................. .......................
http://i5.photobucket.com/albums/y183/conibell/Fue l%20System/8.jpg

................................................5. 7L................................................ .....................................
http://i5.photobucket.com/albums/y183/conibell/Fue l%20System/FuelBucket45.jpg


As mentioned earlier the fuel tank has a stamped recess that the bucket is held against with spring tension, as our bucket has a completely flat bottom there is limited flow access into the bucket. I called EPP today and spoke with Brent, who stated that they had "Clayed" in an effort to determine how much clearance there was from the bottom, he thought .090. I just don't see how that can be without any standoffs or anything to ensure the clearance.

..........................Bottom of Tank...................
http://i5.photobucket.com/albums/y183/conibell/Fue l%20System/FuelTankBottom.jpg
Perfectly flat bucket bottom fits in recess shown above

http://i5.photobucket.com/albums/y183/conibell/Fue l%20System/FuelBucket47.jpg

[01ws6m6conv]

Will this 8.1 bucket bottom fit our top? If so this would be a solution to the fill up at 1/4 tank or burn your 255 pump up. The extra check valves should keep the bucket full eliminating fuel pump overheating,right?

[b727pic]

Will this 8.1 bucket bottom fit our top? If so this would be a solution to the fill up at 1/4 tank or burn your 255 pump up. The extra check valves should keep the bucket full eliminating fuel pump overheating,right?

That is the Million Dollar question......
I am not in possesion of the 8.1L bucket so I cannot answer that. However P004GTO did this mod so I will defer to his knowledge on just what he did to make this happen.

[ddawson]

Just wanted to add two dyno charts to show the difference.

This is Owe5Goat 05 GTO at 482.1 HP / 465.2 TQ. Bill didn't hook up the BAP correctly so notice the AF drop off at about 6.2K.
http://www.carolinaautomasters.com/dynographs/Bill Liebert-Maggie.JPG

This is PO04GTO's latest Dyno at 494.0 HP / 487.6 TQ
Notice thats Brandons is fine at 6.2K with the 8.1L Bucket.
http://www.magnaflow.com/richard/NEW/2%209%20pulle y-TB-MAF.jpg

It works it's just a matter of how far can you go.

[mistermike]

A solution I considered before getting a bunch of fancy Mallory fuel stuff is to add a second pump / bucket to the existing one and run them in parallel. In fact, I purchased a spare pickup assembly for just that purpose. It would take a bit of mechanical creativity to physically attach a second pickup to the existing one, but it's probably doable. After I do some flow testing on the stock pickup, I'll sell it to anyone who might be interested in such an approach.

[ROKS ROKET]

Very interesting thread, I don't like that two spring set up though. They should have made it either three springs at a minimum. It looks like it could some how jam as it rises and drops. I was also surprised by the Plastic design and how small the pump was. Thanks for posting that and going through the trouble of documenting every thing..........

~ROK~

[Owe5Goat]

Just wanted to add two dyno charts to show the difference.

This is Owe5Goat 05 GTO at 482.1 HP / 465.2 TQ. Bill didn't hook up the BAP correctly so notice the AF drop off at about 6.2K.


Damn, rub it in my face. Just :gr_jest:. I know you were just making a point. It's hooked up right now. Two many damn purple wires in the harness where the fuel pump wire is. Oh well, sheet happens. I should have another dyno run with AFR readings in about a week.

[Owe5Goat]

thanks to DDawson for the pic, this is an 8.1L Bucket, not sure of the venturi system differences, but easily seen is the addition of a couple one way check valves on the bottom of the bucket. Also note the bottom of the bucket has small stand off's to raise it off the bottom of the tank somewhat, and the check valves are inset as well.
......................................8.1L........ .................................................. .................................................. ....................... 5.7L
http://i5.photobucket.com/albums/y183/conibell/Fue l%20System/8.jpghttp://i5.photobucket.com/albums/y 183/conibell/Fuel%20System/FuelBucket45.jpg


As mentioned earlier the fuel tank has a stamped recess that the bucket is held against with spring tension, as our bucket has a completely flat bottom there is limited flow access into the bucket. I called EPP today and spoke with Brent, who stated that they had "Clayed" in an effort to determine how much clearance there was from the bottom, he thought .090. I just don't see how that can be without any standoffs or anything to ensure the clearance.

..........................Bottom of Tank...................
http://i5.photobucket.com/albums/y183/conibell/Fue l%20System/FuelTankBottom.jpg
Perfectly flat bucket bottom fits in recess shown above

http://i5.photobucket.com/albums/y183/conibell/Fue l%20System/FuelBucket47.jpg

Sure would be nice to get an installation guide for the 8.1L bucket. I think using it and a high volume LPE, Holley, or Walbro pump will take care of a fueling issues.

[b727pic]

Very interesting thread, I don't like that two spring set up though. They should have made it either three springs at a minimum. It looks like it could some how jam as it rises and drops.

~ROK~


ROK,

The assembly doesnt move once installed. The springs are there just to apply a little pressure to keep the pickup at the bottom of the tank and the vent at the top of the tank.

[ROKS ROKET]

ROK,

The assembly doesnt move once installed. The springs are there just to apply a little pressure to keep the pickup at the bottom of the tank and the vent at the top of the tank.

Ahhhhh, ok that makes sense, it didn't look like the springs were strong enough to have a lot of movement to them. After looking at the assembly again I can see how that works. Thanks.......

~ROK~

[ddawson]

Damn, rub it in my face. Just :gr_jest:. I know you were just making a point. It's hooked up right now. Two many damn purple wires in the harness where the fuel pump wire is. Oh well, sheet happens. I should have another dyno run with AFR readings in about a week.

Trust us we know how you feel. Your case was a perfect example of the AF falling off without the extra help.

b727pic does great write ups so I'm just going to feed him the information as I go. PO04GTO even left me his phone number, so I even have my own Help Desk line :gr_jest:

[MadGoat]

anyone got a part #? I'll go get one.

[b727pic]

anyone got a part #? I'll go get one.

That is the issue at the moment, DDawson has the bucket but none of the #'s are recognizable when a PN search is done. I called Bean's and Martin.....no luck.

I called Airtex got some #'s for a truck application, went to Autozone and physically examined a few units...none were even close.

Then went to the local GM dealer he pulled 4 off the shelf, they all looked like the airtex units.....
I printed out a copy of the pic that DDawson provided, none of the parts guys recognized it....not necessarily a high failure rate item so that in itself isn't all that surprising though...

Interestingly enough all of these new truck buckets, had their pump socks external to the bucket....still seemed to have a venturi return...but didn't want to shell our $300.00 just to dissect a bucket.....

So the hunt continues......

[MadGoat]

I've got my 05 setup out right now. I snapped some pics
http://www.wickedgtos.com/photos/madgoat/category1 051.aspx

[Exotic Performance Plus]

Put it this way, if the holes we added to the bottom of the bucket don't add anymore fuel, then no one has to worry about keeping a 1/4 tank of fuel when they go wide open throttle.
We have not seen a fuel flow problem at 500 rwhp (Mustang Chassis Dyno) with our procedure, and we initiated our 255 Walbro fuel pump and bucket mod purely as a means to prevent fuel starvation for the ProCharger installs that we were doing, not as a way to get rich. Bob



thanks to DDawson for the pic, this is an 8.1L Bucket, not sure of the venturi system differences, but easily seen is the addition of a couple one way check valves on the bottom of the bucket. Also note the bottom of the bucket has small stand off's to raise it off the bottom of the tank somewhat, and the check valves are inset as well.
......................................8.1L........ .................................................. .................................................. ....................... 5.7L
http://i5.photobucket.com/albums/y183/conibell/Fue l%20System/8.jpghttp://i5.photobucket.com/albums/y 183/conibell/Fuel%20System/FuelBucket45.jpg


As mentioned earlier the fuel tank has a stamped recess that the bucket is held against with spring tension, as our bucket has a completely flat bottom there is limited flow access into the bucket. I called EPP today and spoke with Brent, who stated that they had "Clayed" in an effort to determine how much clearance there was from the bottom, he thought .090. I just don't see how that can be without any standoffs or anything to ensure the clearance.

..........................Bottom of Tank...................
http://i5.photobucket.com/albums/y183/conibell/Fue l%20System/FuelTankBottom.jpg
Perfectly flat bucket bottom fits in recess shown above

http://i5.photobucket.com/albums/y183/conibell/Fue l%20System/FuelBucket47.jpg

[b727pic]

Put it this way, if the holes we added to the bottom of the bucket don't add anymore fuel, then no one has to worry about keeping a 1/4 tank of fuel when they go wide open throttle.
We have not seen a fuel flow problem at 500 rwhp (Mustang Chassis Dyno) with our procedure, and we initiated our 255 Walbro fuel pump and bucket mod purely as a means to prevent fuel starvation for the ProCharger installs that we were doing, not as a way to get rich. Bob

Hey Bob,

Just put the link up so folks could compare....I agree your not gonna get rich on a $300.00 turn ...Lol

As stated I dont see how drilling holes is going to have a detrimental effect on the venturi system.....Up until the point where more could leak out than the venturi could supply. Essentially the bucket is nothing more than an internal surge tank who's sole purpose is to keep the fuel pick up submerged. question is what is happening in the bucket at around 1/4 tank capacity, that is different when the tank is above this level. I am wondering if head pressure maybe enough to force fuel into the bottom holes on the bucket, but as the head pressure decreases that force is reduced to inhibit that additional flow????? would be interesting to see what a few thousandths worth of stand offs on the bottom of the bucket would do

Your dyno results results speak for themselves, I also like the fact that EPP stepped up to the plate with an approach to the situation when no other has. The whole purpose of this drill is to find a solution that allows full utilization of the tank capacity.

Keep up the good work Bob, I enjoy reading about all the fun stuff that goes on at EPP!!:hail:

[MadGoat]

I ran w/ no bucket on the dyno with the stock pump and there was no difference. I might order the LFP pump on Monday.

[b727pic]

I ran w/ no bucket on the dyno with the stock pump and there was no difference. I might order the LFP pump on Monday.

My OEM pump and a BAP held pressure between 58-60 up to 8# of boost, my last pull (before the engine came out) I was losing 10PSI @ 10# boost. never had a chance to figure out if the BAP pressure sw gave out, or if I actually found the limits of the pump.

Thanks for taking the time for the test.....

[MadGoat]

Called LFP.. On backorder...

[JCMGTO]

FINALY ! ! ! ! A pic of what I was referring to here in this thread and what I did.

http://www.ls1gto.com/forums/showthread.php?t=5080 7

Basically figured change the jetting or the flow to keep up with the pump.


http://i5.photobucket.com/albums/y183/conibell/Fue l%20System/FuelBucketventurishown.jpg

[catunderhood]

According to AC Delco PN MU1371 is applicable to:

2006
2005
2004

GTO's

IMO it just means you 6.0 guys are 50HP closer to running out of fuel before us 04 guys!!:gr_jest:
You dam right :(

[8MYDUST]

So is this what you enlarged on the bucket?

[ddawson]

It's a balancing act.

Upgrade the pump with the stock bucket and the buck runs dry as gas can’t flow in fast enough.

Drilling the Bucket in anyway shape or form and gas won’t stay in the bucket once the level starts to lower.

You need to allow enough gas flow into the bucket and not allow the gas to leave the bucket.

[b727pic]

Just ordered a Walbro fuel pick up....thanks to MisterMike for pointing me in this direction.

Am going to try and incorporate a fuel return system to the bucket and utilize this pickup as well.

[b727pic]

had a few spare moments this afternoon, and decided to play a little with the pressure regulator assembly. Now keep in mind my test equipment is nothing more than a shop air water separator and regulator assy. but nonetheless here is what I found.

There is no flow through this manifold assembly to the venturi feed, until the pressure regulator starts to bypass pressure. I played a little using shop air, the regulator starts to bypass at around 60PSI and appears wide open around 65PSI. My intrepretation of this is, if fuel pressure drops below 60 PSI at the regulator, at best you have minimal flow at worst no flow through the manifold and thusly nothing powering the venturi feed system. Essentially all you have is gravity feed through that little check valve in the bottom of the bucket. So in this scenario, not only is your fuel pressure low, additionally you have no "power assist" to refill the bucket.

Assuming my thought process is on track here, this might explain the 1/4 tank bucket problem... and thusly fuel pump overheating....with alot of fuel in the tank the force of gravity to feed the bucket through the check valve is greater than when at a lower level?????

Now all this makes sense when I am looking at fuel pressure to the rails being 52-58PSI, I am assuming the pump is throwing all it can to the rails and nothing is being bypssed through the regulator to the venturin system.

In OEM configuration, with 28 LB injectors I suppose the pump output is exceeding demand and is creating enough pressure to feed the injectors and enough bypass fuel through the regulator to power the venturi feed.

http://i5.photobucket.com/albums/y183/conibell/Fue l%20System/PressureReg.jpg

So here something to ponder, if a return system is installed, along with a boost reference regulator. I see no reason why this "in" bucket regulator could not be replaced with a fitting, and the (or some) of the return fuel from the regulator could be powering this venturi feed at all times.....

Something along these lines....would need to be a 90* fitting though
http://i5.photobucket.com/albums/y183/conibell/Fue l%20System/pressregbypassexample1.jpg



Thoughts????
Comments???

flame suit is on fire away:bubbrub

[8MYDUST]

I am not an expert at anything on fuel pumps but I have a theory.

From all the pics that I have seen I have been wondering why we don't just get rid of that regualtor assembly and cut three holes on the bottom of the bucket and then run a pump like from racetronix (see Pic attached) hook up the wires to the pump and BAM done. Unless that regulator is sending a signal to the computer or something if so then NEVERMIND.


Does anyone have pictures of a C5 fuel pump like the ones on our GTO's maybe we can cheat and use racetronix C5 fuel pump kit and put it in ours.

[b727pic]

I am not an expert at anything on fuel pumps but I have a theory.

From all the pics that I have seen I have been wondering why we don't just get rid of that regualtor assembly and cut three holes on the bottom of the bucket and then run a pump like from racetronix (see Pic attached) hook up the wires to the pump and BAM done. Unless that regulator is sending a signal to the computer or something if so then NEVERMIND.


Does anyone have pictures of a C5 fuel pump like the ones on our GTO's maybe we can cheat and use racetronix C5 fuel pump kit and put it in ours.

I think the answer for most folks under 550 RWHP is going to be the 8.1L bucket and the Walbro 255LHP...a few have even pushed 600 RWHP with a BAP.

Unfortunately an entire bucket assembly must be purchased.. I had one quoted today that was $500.00 :eek2: Hence my looking into alternatives to keeping the bucket full....

Another thought is to follow along the lines of the EPP approach, like you also mention. However I would suggest a check valve like the 8.1L buckets....I have been unable to source anything remotely similar. I called a few aircraft supply places, and as suspected very quickly the 8.1L bucket looked real attractive price wise!!!!

[bullygoat]

Ok, so the pressure regulator bleeds off pressure when the supply line and fuel rail reaches roughly 62psi(to keep it simple).
So the pump can't keep up with larger fuel demands(read drinking the well dry).
If it could supply enough, then the regulator would open up and bleed off into the venturi jet causing the
fuel bucket to fill up, correct? If so, it would seem that you need a pump that is able to supply a larger amount
of fuel at a greater pressure. Or is it that even with that pump,
the venturi isn't large enough to let the bucket fill up with the larger demand?

Tim

[b727pic]

Ok, so the pressure regulator bleeds off pressure when the supply line and fuel rail reaches roughly 62psi(to keep it simple).
So the pump can't keep up with larger fuel demands(read drinking the well dry).
If it could supply enough, then the regulator would open up and bleed off into the venturi jet causing the
fuel bucket to fill up, correct? If so, it would seem that you need a pump that is able to supply a larger amount
of fuel at a greater pressure. Or is it that even with that pump,
the venturi isn't large enough to let the bucket fill up with the larger demand?

Tim

I am speculating this to be the case.

The walbro should be of sufficient output to power larger fuel injectors and the venturi system. however there is several documented cases of the pumps burning up, the cause is assumed to be loss of fuel around the pump pickup area....ie... the bucket is empty.

I suppose the next thing to try is to rig up a test setup with solvent or kerosene, diesel, some fluid with near the same viscosity as gas and see what is happening with the venturi feed at various voltages, flow demand etc....

[JCMGTO]

So is this what you enlarged on the bucket?

Yes that whole piece will pop off. And reading down further in this thread is what I had figured with the regulator. So (as I mentioned before) I could be way off, but I drilled the jet bigger, so I would have more flow. Remember I am also running a KB BAP, which with it I use to still see my pressure drop. But now with the BAP cranked and the jet drilled it has seemed to balance it self out. the BAP keeps the PSI up to let the regulator opens and with the larger whole in the jet seems to fill the bucket back up while under heavy throttle. Where as before the pressure would be up and under throtlle it would slowly drop. Not enough return. I can expalin better in person then in words. But with the BAP cranked (not maxed, which it used to be and saw pressure drop) pressure stays up and stays constant after drilling the jet out.

Now I do need to see how the new epxoy is holding, that is the only concern or one of, cause I could be wrong in my theory but keeping fingers crossed. Please let me know thoughts. :wall:

[JCMGTO]

Wow no more thoughts on this?

[b727pic]

Wow no more thoughts on this?

I think it has basically come down to this.....

We need more fuel flow, additionally a way to fill the bucket faster than our OEM bucket will. this can be accomplished in various way's.

1. Get the 8.1L bucket / Walbro mod, looks like your good to 500ish a little more with a BAP

2. utilizing our OEM bucket, install the walbro and find another way to keep the bucket full....ie...install a return system, and run a portion or all of the return fuel back to the bucket.

[Steel Chicken]

if you were to install a return system, what would be involved? sticking a return line on the fuel rails? would an additional pressure regulator be required?

[b727pic]

if you were to install a return system, what would be involved? sticking a return line on the fuel rails? would an additional pressure regulator be required?

My .02 ...

Either live with the limitations of the 8.1L bucket set up..
or
be preparred to go an entire new fuel system install.....ie similar to Trak Day.

to accomplish a new system you will need.

1. high flow rails......or modify OEM
2. high pressure EFI pump (S)
3. Proper size fuel feed line, and return line.
4. Regulator assy.
5. Tank modifications to accomodate pump feed, and regulator return fuel.

You will have to find a place to install a return fitting, ie weld in a fitting or bung. Instead of just dumping the fuel into the tank, you will need a way of directing the fuel to the bucket. Off the top of my head I would envision a fitting on the inside of the tank, attach a hose and direct that flow to the bucket. What you don't want is to creat too much swirl or distrubance in the bucket.....just basically fill it up....example would be how your toilet tank fills, little or no turbulence, the level just rises.

From what I have read a proper system should be something along these lines.

tank -->Pump (S)-->fuel rails-->Regulator-->tank

If a regulator is added at the rails I think you will want to disable the regulator in the tank...keep in mind the OEM regulator seems to be in full relief mode at 65psi, if trying to utilize a boost reference regulator you will be bypassing fuel in the oem bucket instead of directing that flow to the motor...

However if an in line booster pump is utilized, retaining the oem regulator may be possible, still sorting through this one. One thought I had was to install a walbro (in tank), make the appropriate mods to the tank itself, ie...sump points and return set up. then have a sump point feed to an in line booster pump such as a Weldon 600A (pick your poison as to what brand) with the existing OEM bucket feeding into a T at the inline pump outlet. My BAP pressure sw. could then control the booster pump (3PSI of boost) to then "assist" the in tank walbro with feeding the engine. Meanwhile the pressure out of the in line pump will be greater than that of the "in tank"...this should cause the bucket regulator to go full open, which will induce the venturi system to help fill the bucket......

Hard to put into words, I can envision the system...just need to work it out some more. The 727 I fly has an optional fuel pump override set up which is what prompted me to think along these lines. basically while all pumps may be on, some are a slightly higher pressure, those tanks with the higher pressure will overide the lower ones and feed the engines......