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· Old Guys Rule
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3,384 Posts
ddawson, need your help, i have a stock fuel system, i read somewhere that you can drill holes around the bucket in pre determined spots, that will let the pump get more volume, anything to this. thanks, rob v
The whole purpose behind a semi sealed bucket with a venturi feed system is to keep the fuel pump submerged when the fuel tank level is low. while drilling holes in the bucket will help higher HP applications keep up with fuel demand, this approach negates keeping the bucket full with low tank levels.....ie easy in = easy out. You could make this work, I just wouldn't romp on it hard with less than a quarter tank of fuel.

There is no easy cheap solution to fueling our GTO's. the 8.1L bucket mod is just about as cheap as it gets, but still a PIA to accomplish. Get the parts as Dan has outlined, and plan on a nice Saturday to get it all installed.

FYI, if you plan on an FI boost reference setup, this is only the beginning:)
 

· 427 GTO
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59 Posts
Fuel Delivery

Some tips for converting the GTO Fuel Bucket to the 8.1L Bucket.

Parts,
8.1L GM Part Number GM#88965372 or AC Delco PN MU1312
Revised Part Numbers GM # 19133455 or AC DELCO PN MU1417
Float Sensor unit part number is GM#88965379

http://www.magnacharger.com
The Magnacharger part number is #31-12-00-026 for the H2 Hummer.
This included the;
1 Fuel Pump, In-tank, Walbro GSS340
1 Fuel Pump Inlet Screen
1 Fuel Pump Sleeve
2 16-14ga. Push On Term Female
1 Fuel Pump Discharge Hose
1 Fitting, Fuel, In-tank Pump

http://www.autoperformanceengineering.com/
APE Flexible Plastic Hose
You may also want to the get the APE Connector instead of the Magnacharger Push on Terminals.
Walbro Connector with Butt Connectors.


You will also need two small hose clamps for the above line and 1 large hose clamp for the Fuel Neck and a box of Heat Shrink Butt Connectors.

UPDATE
A seller on Ebay "ID is global-automotive" sells a complete bucket that INCLUDES the correct Float Sensor.

Also if your careful you can use the 8.1L buckets flex line and attache the GTO connector to the end of the flex line so you only have 1 worm clamp.
Thanks to those who keep finding out more information on this setup.

Picture of Finished Bucket.


Removing the tank,
http://www.lingenfelter.com/documents/gtofuelpumpupgrade.pdf

Over View,
Remove the fuel tank and pull the GTO Bucket.
Unclip the two Connectors from the top of the bucket
Remove the C Clip from the rod and separate the upper and lower section.
You will use the Upper half on the 8.1L Bucket so place it somewhere safe.

Modify the 8.1L Bucket.
See http://magnacharger.com/pdf/manual-HummerH2.pdf
Steps 20 though 42
The only difference is you will NOT be keeping the upper half.
Don't attach the bottom cover just yet.

Now you want to use the GTO Connectors and Butt Connect them to the 8.1L wires.
Take care that you get positive and negative correct on the Fuel pump.
If you use the Magnacharger kit you will use the spade connectors on the GTO wiring.

For the Float sensor wiring,
Place both Sensors in front of you. The new one points right and the GTO one points left.
Using the GTO connector Butt connect the left wire to the left wire of the new Float Sensor.
You can verify the correct wiring by using an OHM Meter. Empty is the higher number while full is a lower number.

Now you can connect the GTO Upper half to the 8.1L lower have. Slide the rods into the bucket and use the C Clip to hold it together. Attach the 8.1L bottom to the Bucket now. To line it up correctly the GTO upper half will be at the 3 O'clock position and the Float Arm will point to the 2 O'clock position.



This was the hardest part at the time but I found a better solution.
Making the fuel line that attaches to the tank,

Use a razorblade knife and cut the tubing off the connector that attaches to the fuel tank. Do the same thing for the 8.1L 90 Degree Connector that comes off the Fuel filter.

On both Connectors sand the barbs down enough to you can get a good fit with the APR Flex Line then use a hose clamp on both connectors.





Snap the 90 Degree Connector back into the Fuel Filter.



You're done and it's time to reassembly.

Thanks to PO04GTO and b727pic for helping me out.

I drove around town with the "You Need Fuel Stupid" flashing at me and had no problems.

I hope this help. Any questions??
In your estimation this would support how much horsepower
 

· Supercharged '04GTO
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610 Posts
It allows you to run low on fuel without staving the fuel pump.

The GTO bucket doesn’t allow enough fuel into the bucket with a high flow pump. The pump will suck the bucket dry leaving the pump with no fuel and no cooling.

People have added holes to the bottom of the GTO bucket which fixes the supply issue but as the tank runs low the holes allow the fuel to drain out of the bucket again leaving the pump with no fuel. This is turn burns out the pump.

You can see in the last picture if you look closely that there is fuel in the bucket sitting on my driveway. No fuel is leaking out.

The 8.1L bucket allows enough fuel to enter the bucket without modification and also doesn’t allow the fuel to drain out when the fuel tank gets low.

At this point we know it can supply 500HP which is fine for me but I don’t think we know were the 8.1L bucket becomes a limiting factor again.
The bucket on the stock set-up rests on the bottom of the fuel tank, so you dont have a problem with fuel running out of the bucket unless you are in the habit of running your fuel down to almost empty. I installed the Ligenfelter fuel pump system which puts out a max of 300lph @ 16 Volts and only removed the old stock pump and drilled 3 holes in the stock bucket about 3/4 inches off the botton. With the bucket resting on the bottom of the tank, those holes will not flow fuel out unless the fuel tank is almost dry. I usually fill up @ 1/4 to 1/8 fuel remaining and I've had NO problems. Pump was $139. plus shipping and VERY EASY to install. Hardest part of the job was dropping the old tank. I wanted the 8.1 L bucket setup but this works as well and was a lot less expensive with NO PROBLEMS EITHER RACING OR CRUISING. I just have to keep the fuel level above about 1/8 tank. With all the hp I put down, I needed 79lb injectors and the stock pump would not feed them properly so I was forced to upgrade.
 

· Registered
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1,064 Posts
I did this mod and it was pretty straight forward. I have had no problem and have run my tank down to 1/8 to see if the level sensor reads correctly and it does. I also had read that some people's fuel level needle moved up slowly after a fill up, but mine is no different from stock. Had the tank in and out in less than two hours (first time removing tank). I did the 8.1 mod before the tank removal. I purchased a stock fuel setup from ebay so that I could save my stock one just in case I screwed something up.
 

· Registered
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2,642 Posts
i finally ordered all the stuff to do this mod. I have a spare walbro pump in hand already, so i just ordered the bucket from ebay, and all the little parts from APE, hopefully ill have everything a couple days into december
 

· Back in Black
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492 Posts
OK I am going to do this also as I'm 472 wheel on the stock pump NA adding the spray so I already had a LPE pump kit so I just bought the sending unit referenced in post #151 Am I correct in thinking I can rig this to work with no other parts ?? appears thats correct I see post of people buying hose somewhere and others saying you can make the 8.1 units hose work .. Guess I will know better when its in my hands next week. I figure I can't sell the car so might as well see if we can put 650 rwhp down and go have some fun !!!
 

· Registered
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2,642 Posts
has anyone else had a problem with the gauge not reading right after filling up? when i put the bucket in it read about 1/2 tank, which i think was right, and went down from there. when i filled it up it went back to that 1/2 mark, and then after driving for a little while it eventually made it to full and went down like normal from there.

i filled up again yesterday and it did the same thing. i went to 1/2, and then after driving it slowly went to full. anyone know whats going on???
 

· Registered
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2,642 Posts
it reads, but it also reads correctly. it just takes between 5-10min to get there after filling up. ive got the battery disconnected again but it has a full tank right now, so ill see what comes of it the next time i fill up.
 

· Premium Member
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15,570 Posts
Discussion Starter · #170 ·
Could be a bad sensor or float.
 

· ChimChim is in the HD's trunk
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5,305 Posts
I have a full GTO assembly in my basement in a box. If anyone needs it for parts send me a PM. I want to get rid of the whole thing.
 

· Registered
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68 Posts
Does anyone have an 8.1L bucket on the bench? I could really use these dim's.

Resurrecting a great thread....

I need some dimensions of the 8.1 bucket:

1) Height of the bucket only.
2) The largest diameter on the bucket NOT including the fuel level sensor.

I may try to retrofit this unit into another tank but using an LS1/ GTO Magnacharged drivetrain.

Thanks a bunch.
 

· 1 of 90
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1,259 Posts
Does anyone have an 8.1L bucket on the bench? I could really use these dim's.
I have one coming this week, when it arrives I will get the dimensions for you.
 

· Registered
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159 Posts
Hello GTO people, I did this mod back in March of '06, when this thread was started. I got the bucket off ebay and, and the pump from Lingfelder.
I am running 62lb injectors, maf-less speed density tune, GT67turbo and made 525 rwhp on the dyno, with my tuner's help (Jeremy Formato).

The fuel gauge works perfectly, and I have had no problems after nearly 4 years.

As I remember, I think that I had to remove the whole damn tank, right after putting things together the first time. Something got hung up, and the gauge didn't work. But, I took it apart and reassembled it, and it worked right the second time.

I am still running low boost, so I have a long ways to go, tuning wise. I see about 9lbs on the boost gauge, and so I bought some heavier springs for the wastegate. I haven't installed them yet. Looking to run the boost up to about 15 or 20 lbs. (its got forged internals). I took a break from all the modifying, and just drive the car.

This is a really good mod . Good luck .
 

· ...
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1,121 Posts
Does anyone have an 8.1L bucket on the bench? I could really use these dim's.
1) Height of the bucket only.

The molded D-shaped bucket is 6.750" tall- if you include the raised section for the sending unit mount, it's 7.235" tall overall.

2) The largest diameter on the bucket NOT including the fuel level sensor.

Mine measures 5.040" at the top (with inner piece in place), tapering to 4.950" at the bottom
 

· Registered
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Thank you very much Ed.

If you have the flange OD of the upper section that would also be helpful. Someone told me it too was 5" but that makes no sense given your dim's.

Thank again, you're saving me from having to buy one and then find out it won't fit.
 

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I've got the garage buttoned up for the evening, Carl, but will pull that info for you tomorrow AM.

.
 
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