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PostPosted: December 30, 2010, 12:05 am 
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Hey guys,

Some time ago I mentioned how I was doing my In-tank fuel pump and received several emails about it. Finally getting around to writing up a how to.
Pretty much all modern cars use a fuel bucket system for their fuel pumps. This means instead of having baffles etc in the tank, you have a bucket that you keep full of fuel that the pump draws from. The fuel pump is always submersed, and never sucks air making them last longer, run quieter, and push better. The way the buckets get filled up is by: gravity- one way valve allows fuel in but not out, tank is full higher than the bucket keeping it full. Or a jet pump which uses a little of the main electric pumps pressure/flow to draw fresh fuel into the bucket using a venturi jet. The return line also dumps all unused fuel into the fuel bucket.

So, what I did was collect OEM fuel pump modules where the pump had burned out (they were free). I collected several and forgot which one I used.... oops. 2002 Silverado maybe, definitely GM. I removed everything but the bucket, jet pump and one-way valve and installed a new walbro 255 pump (pretty good pumps). I bought a Tee fitting from ZZperformance.com that has a small outlet to feed the jet pump. Apparantly this is obsolete because you can now buy a walbro pump that has the outlet to feed the jetpump.
http://www.zzperformance.com/grand_prix ... &catid=113
It would be better that way because using the Tee the fuel pressure bleeds down every time you shut off. Tip: heat the end of the plastic hose that goes to jet pump then stuff it over the fitting. It will shrink down and fit snug when cold.

I then added a baffle (which I wanted to control slosh anyways. This could be done w/o a baffle) to my fuel cell by cutting a slit in the top, and 2 smaller ones on the bottom. Slid the flat baffle in and had it TIGed up by a pro. I then clamped the bucket to the baffle using 2 large hose clamps. The fuel bucket sits directly on the bottom of the cell as it should and is directly under the return line so return fuel will dump into the bucket.
I then used SUBMERSIBLE fuel hose (must be SAE 30r10 hose or it will rot/crack) and attached the fuel pump outlet to the FEED tube which goes to the AN fitting on top. For wires I used 2x "liquid tight connectors" from marinco. You drill a hole in the cell, tighten the connector and then run the wire through it and tighten it. A rubber O-ring clamps tight onto the wire; sealing it.

Attached is a photo of the bucket I used. Ignore the float; It's not required. The hole with the black rubber sleeve is where the electric fuel pump goes. Then you stick a filter sock on it inside the bucket. The black hose is for the jet pump and gets pushed over the small nipple on the electric pump (or in my case, a Tee fitting).

The attached doodle is how the jet pump works.

Hope this helps. So far it seems like a good system and the jet pump is definitely working.

Cheers,
Cory


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File comment: fuel bucket I used
module 001.jpg
module 001.jpg [ 352.97 KiB | Viewed 3264 times ]

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PostPosted: December 31, 2010, 12:15 am 
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C10CoryM wrote:
I then used SUBMERSIBLE fuel hose (must be SAE 30r10 hose or it will rot/crack) and attached the fuel pump outlet to the FEED tube which goes to the AN fitting on top. For wires I used 2x "liquid tight connectors" from marinco. You drill a hole in the cell, tighten the connector and then run the wire through it and tighten it. A rubber O-ring clamps tight onto the wire; sealing it.


Excellent information. I knew there was some spec of flexible hose out there for running the pump to the top of the tank. I just ordered some for my car since the regular SAE stuff was looking pretty bad last time I was in there.

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PostPosted: December 31, 2010, 12:31 am 
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Good post, very helpful for those trying to avoid a two pump system or a sump on the typical long skinny 7 tank. If my recent efforts to avoid fuel starvation don't succeed then I'll try the "bucket" approach.

Ron

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PostPosted: January 1, 2011, 7:51 am 
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What do you use for the "jet pump"?

Mark

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PostPosted: January 5, 2011, 2:07 am 
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michmark wrote:
What do you use for the "jet pump"?

Mark



The Jet pump is part of the fuel bucket from the GM truck. I can't think of any GM newer than 2000 that does not use a jet pump. Ford and Dodge also use them heavily. Imports, not so much.
In the picture above you can see the black hose that feeds the jet pump. It uses that hose to create a suction that pulls fuel into the bucket from the bottom of the fuel tank.

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PostPosted: October 27, 2016, 10:21 pm 
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Cory, I looked through your build log, but couldn't find any other information on this setup. Do you have and additional photos of how you put this all together including the tank it went into? I'm assuming you built your own fuel tank.

I'm thinking I would like to use this concept in my own build. In my case, I may want to select a Ford unit, primarily so the float/sender would be compatible with my (donor) '94 Mustang ECU and fuel gauge embedded in the donor instrument cluster.

My donor unit does not use the fuel bucket concept although it is an in-tank system.

Thanks,

Lonnie

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PostPosted: October 27, 2016, 11:42 pm 
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Hey Lonnie,

Don't think I have much in the way of photos.
I actually used a RCI aluminum tank. I wanted a baffle to keep the fuel from sloshing as bad, so added one. My fuel bucket is just clamped to it and I reach through the filler-flange hole to do so (it's not overly pleasant). if I were to do it again, I would duplicate the OE further and use their mounting system (or similar) and have the baffle separate.

GM and Ford used the same Ohms for their fuel levels for a lot of years; you may get lucky.

If you are unfamiliar with how GM fuel pump buckets fit, watch this vid: https://youtu.be/3mjaQv-VcZU?t=13m22s

The top of the assembly is held down by a lock-ring, and seals with an O-ring. The bottom of the assy rests on the bottom of the tank. The assy is too long, and you have to compress it (it telescopes with springs for tension) on installation. I would replace the lock-ring with a bolt on flange, and the O-ring with a gasket if required. If the tank is too tall/short for the assy, I would change the length of the assy at the telescoping tubes. You can get pigtails for wiring, and adapters to AN for the lines so that part is easy.

Ford did use fuel buckets as well for some models/years. They tended to be quite small and, iirc require a locating spot on the bottom of the tank to keep them from flopping around. The GMs are rigid and secured by the top only.

Let me know if that helps, or if there is anything more I can clear up. My painkillers are starting to kick in so I hope this makes sense :roll:

Cheers.

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PostPosted: October 27, 2016, 11:55 pm 
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This is sort of what I had in mind for mounting. Could probably figure a way to do it w/o welding though.
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PostPosted: October 28, 2016, 12:15 pm 
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Yes, that video and the additional info were very helpful, Cory. The most economical way to go would be OEM replacement equipment through Rock Auto or Parts Geek. So, I'm hoping I can make that work out some how.

I never did fully understand the jet pump setup in your example, however. I know from documentation that my '94 Mustang donor fuel pump puts out 40 PSI. It's the constant flow type with a return line for excess, unconsumed fuel. Later models of Mustang had a variable speed fuel pump that was controlled by the ECU. It varied fuel pump speed to keep fuel rail pressure constant at the injectors, and had no return line. Thus, my donor ECU does not know how to control a variable speed pump, only the off/on of the constant rate type. Is the jet pump a constant rate type, or variable speed type?

Thanks again,

Lonnie

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PostPosted: October 28, 2016, 12:43 pm 
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I wonder how effective that is over having one-way valves into the box. In a turn, if fuel sloshes away from the inlet, the jet pump may blow air into the box. I guess that's no different than a one-way valve not receiving any fuel. Under heavy acceleration, nearly all the fuel may be consumed by the engine, leaving little for the jet pump's "motivation."

I guess I don't see this being any more effective than having a baffled pan with one-way valves leading to a central pump box, like that below. With the baffles, fuel doesn't have any choice but to flow into the center section and once there, can't flow back out. I don't mean to steal your thunder, just offering up alternate approaches.

Image

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PostPosted: October 28, 2016, 10:15 pm 
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The jet pump is just a siphon pump that uses the main fuel pump's flow to create a little suction. Fuel in the main line rushes past a small restriction, which creates a low pressure area. That's where a hole is to suck fuel from outside the bucket into the bucket. It's no different than the thing that sucks soap into your pressure washer, or air into your fishtank. Since it is a jet pump with no moving parts, it doesn't care if it sucks a little air as you corner/brake on low fuel. Any air it pulls in will separate in the fuel bucket before the main pump sucks it in. I have seen vehicles with this setup run until the fuel tank was completely empty before it died. Total fuel left in the tank and bucket would be <100mL. They also tend to run totally fine until they just shut off and won't restart.

Really the bucket is no different than baffles. It's a mechanism to hold fuel around the main fuel pump pickup as long/often as possible. That being said: The bucket is better IMO. It is sealed tight so no fluid will escape which allows it to run lower before starvation. Meanwhile the jet pump gulps up any fuel it sees. There is also a one-way valve that let's fuel in via gravity (this is where the bulk of the fuel comes in once the fuel level is lower than the top of the bucket). It also leaves the fuel pump fully submerged in fuel even when the tank level is low which extend pump life. OE tanks often have small channels to get the very last of the fuel to the jet pump. Flat bottom tanks may not perform as well. Because of the angle mine is on, I probably would still have around 1L of fuel left when my car shuts off. I'm not too concerned, but if you were building a full-prep autoX car or something you may want to have the bucket in a small sump (or just hammer that part of the tank lower). GM buckets probably hold 1-1.5L of fuel which should be enough to get any reasonable motor around a corner. If not, get a bigger bucket :wink:

The fab work to install a bucket is also pretty easy compared to good baffles. Also cheap. Looking on Amazon and you can get a good pump assembly for $167USD (can find them for $60 but that seems too cheap). I paid more than that for the Walbro I stuffed in mine.


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PostPosted: October 28, 2016, 10:26 pm 
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In case this helps show how easy it would be to install one of these into a typical aluminum/plastic fuel tank. BTW, many pumps come with pigtails.


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PostPosted: October 29, 2016, 8:58 am 
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Thank you for the photo above and the additional explanation, Cory. They look like they'd be pretty easy to install.

Cheers,

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PostPosted: October 29, 2016, 10:44 am 
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Check the car the bucket/jet pump is from. My Blazer pump is like that but puts out over 90 psi if blocked. Normal pressur with external regulator is over 60 psi. Much higher than some other systems.

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