Fuel Sump ideas and Horror stories

[SF_SN888KE]

Need to build an aluminum fuel sump (have a custom fit aluminum fuel tank) to relocate my fuel outlet lower (from the top of tank) and relocate my electric fuel pump lower. Not for drag racing, but long story about vapor lock at the Cobra Bash .... (Electric fuel pump is about 6" above tank with fuel pick up tube ... this is BAD for Aeromotive A1000 electric fuel pump)

Can not weld the steel Competitive Engineering fuel sump pan on my aluminum tank and will have to go custom built aluminum. Can not use fuel cell, don't want to cut up the tank and put the pump in the tank.

Any recommendations on the SIZE of the fuel sump when running fuel injection and Areomotive A1000 electric fuel pump? Smaller vs. Larger? Looking at 10" deep x 8" wide by 3 1/2" tall. (this would keep bottom of fuel sump parallel with pavement and allow me to go in/out of the garage). Could go wider (up to 36") for larger fuel capacity (adds 2 gallons), but would probably have to add baffels 12" apart to reduce sloshing.

People have cautioned me about the sump and fuel line getting ripped out on speed bumps and trash on the road. Any HORROR stories out there about your fuel sump?

[Rick 427 Cobra]

How about a high volume, lower pressure pump in the tank feeding a separate surge tank containing the high pressure pump. Volkswagen does it this way.

[PANAVIA]

http://www.fordfuelinjection.com

and http://www.fordfuelinjection.com/Inject_your_horse3.pdf


Check out their site, it may give you some ideas.

--Steve

[289fia_cobra]

Ron,
Thinking a little about how CER did the tanks, I'm thinking maybe see what CS does for their continuation cars for ideas. I don't know of anyone that ownes one but if a BACC member has one, maybe you two can meet.

Another thing to do would be to spend the "winter" removing the old tank, getting the rough dimenions and use cardboard to mock up a different tank with your requirements.

Perhaps some of fabricators in the Bay Area (i.e. Bruce Canepa) that have race experience can help. Won't say it'll be cheap but nothing in the custom-fab world ever is.

[vettestr]

I am a little surprised a 6" lift would be a problem for your pump but a few things come to mind. Reducing the restriction to the pump inlet is a function of lowering the pump or increasing the tube diameter. If inlet is now #6 or 3/8 increase to #10 or even #12 AN. The catch may be ability to increase the tank or bulkhead fitting but this has to be easier and less $$ than building a bottom sump.

I have had to use a pick up tank like mentioned by rick427. I plumbed inlet and return into the pick up tank on the top. The first pump (rated for continuous run) was used to fill a 2qt tank that simply kept it full. A line or fitting on the top of this tank dumped back into main tank only if tank was full. The 2nd or main fuel pump picked up fuel from this tank. The 2nd fuel pump was a demand type pump (turned on and off) as needed to maintain a fixed pressure to the carbs. A continuous type with a return could be used with additional bung or return to main tank.

[thudmaster]

Ron, what ever you do, good luck.
Now bring your sticks up here..........

[SF_SN888KE]

Great links and thoughts ... especially taking the sticks up to Yuba City!
The lift is about 6" above the tank, but Aeromotive recommends their pumps to be at the level of the bottom of the tank or below, and is a "push" not a "suck" system. (although I'm thinking that this sucks). The pump has to work harder if it is above the level of the tank, causing more heat, especially in altitiude and 100 degree weather = potential vapor lock. And forget about the addded heat in the engine compartment!
I believe the intake tube is large, maybe 3/8" or 1/2". Building the fuel sump and welding is only a couple of hundred, while adding an in-tank pump or building a new tank, or Canepa is ... $$$
As I recall, the CE sump is about 0.5 gallons. Consider the fuel sump as a small tank, but I can make it bigger if needed? What is the optimum fuel sump size (for the street? or for the track?)
The CER tank had a fuel outlet on the right side, bottom of the tank, but the weld/bung cracked and we had to put an inlet at the top (for the 2005 WSCB!).
Will also add a shut off valve to make changing fuel fiters easier. Also, living in San Francisco and going up a hill ... I want to be sure that fuel is getting to the pump.

[EarlsflyinCobra]

Check this link out, it might help.....7th item on the page counting across.....twice, then starting on the third row..............I installed one of theses in my tank and it was a breeze....haven't had an engine start yet but don't think it will be a problem....................good luck

http://www.docskustom.com/tank_accessories.html

[289fia_cobra]

Hills in SF should never pose a problem with the fuel tank. I mean think about it: Steve McQueen was racing around in a 67 FB Mustang up and down SF. If he can do it, so can you!

[xlr8or]

Many people run a separate "swirl pot" for fuel injected cars that use a typical electric pump from the main tank to the pot. The pot feeds the main pump to provide adaquate pressure to the FI. Return line goes to the pot so the first pump only has to keep up with what is acually used at the engine and then vent the pot back to the main tank for an overflow. This will keep the expensive main pump supplied at all times so you don't burn it out from cavitation. A side benfit is there are no slosh problems becuase the swirl pot is always filled to the brim with fuel and can be located above the main pump for gravity feed.

[SF_SN888KE]

"swirl pot" sounds like a goog idea, but don't think I have the space. Think of the fuel sump as a "swirl pot". What size should the swirl pot (fuel sump) be? 1/2 gal? 3/4 Gal? 1 Gal?

Also interesting in-tank pump ideas - but that would require cutting a new hole in the top, will call them and double check and see if they can work ... lots of options. If the fuel sump doesn't work, I can always try the in-tank from the top.

Steve McQueen handled the hills of SF like Evil Kinevel, but you don't get vapor lock by catching air flying over the hills of SF on a 55 degree summer day with a full tank of gas, costing $.25/gal! Maybe I should get a 67 FB mustang? I'll put that on my bucket list.

[BossCER]

Hey Ron,
Jump in that thing and head down to Pismo this weekend. I'll be there on Sat w/ the silver car.

[Aussie Mike]

I messed around with this stuff quite a bit.

With injected cars and high pressure pumps they don't create a lot of suction and have real trouble drawing fuel up out of the tank. You need to either make sure the pump is installed down low below the fuel level or have a swirl pot that will give you a head of fuel to keep the pump constantly supplied.

The other issue you have with injected fuel pump setups is that if the pump pickup becomes uncovered you lose fuel pressure and the car will stall or hicup straight away. This wasn't a problem with carburetors as you had a constant supply of fuel sitting in the bowls it. It didn't matter if the pump took a few seconds to catch up with demand.

There are a few options for fixing this. I ran an in tank pump to feed a swirl pot that keeps a constant head of fuel available for the high pressure pump.

With your setup to avoid any modifications to the tank etc I would look at installing an external carter electric pump to draw fuel from the tank and feed it to your aeromotive pump. The carter pump is a low pressure diaphram pump rather than a vane pump like the holley so they have good suction and will pull the fuel up out of the tank. You may get away without running a swirl pot and feed direct from the carter to the aeromotive but having a swirl pot in between would help. The return line from your EFI pressure reg should go to the swirl pot and there should be a return from the swirl pot to the main tank.

I'm currently running a low pressure in tank pump in the main tank and this feeds a swirl pot mounted up high in the left rear of the car this feeds down to a high pressure pump that feeds the fuel rails.

My next project is to build a stainless fuel tank with the swirl pot inside it. I will either use an in tank high pressure pump sitting in the swirlpot or keep my Bosch 044 and mount it down low near the bottom of the tank.

Hope this helps.

Cheers

[ByronRACE]

I'm going to go outside the box slightly, having seen your car and situation.

What I would do would be to put a service hatch on the top of your tank (and in your trunk floor) and build the solution into that, and I'd use a completely different pump solution to drop the fuel heating problem down significantly.

A single Walbro GSS342 pump can support 500rwhp and is tiny by comparison to the A1000. If you're making more than 500rwhp, then use two. They are OEM quality pumps, last a long time, and will be silent compared to your exhaust note. They also don't heat the fuel as much and when they fail, they don't fail in such a way that it slowly leans out your mixture...when these gerotor pumps die, they just die completely most of the time. That is, if they *ever* die. I've seen them go 100k+ miles routinely.

The pickup screen/filter is part of the pump. All you need is a hangar to hold it near the tank floor, a baffled area to keep fuel to it at all times (perhaps with ball-check valves or trap doors), and a feed-thru for +12 and gnd to power them.

The baffle/box area can be built into the hangar such that it's resting on the trunk floor when the unit is bolted into place. To bolt the fill plate in place, you can use rivet nuts on your existing tank. If you make your fill plate a standard stock car size you can use the existing gaskets that are available to seal it. If the material on the tank is too small, you may need to make a nut plate (backing plate) that you could thread instead of using rivet nuts. You could bond that into position, or use a couple small flat-heads to hold it in position.

You want the pumps in the center of the tank, if possible (the corners slosh dry more often), and the baffled area as tall as practical, and enough volume to supply during transients (a pint, or more). You can hold the pumps in with hose clamps; the hangars need not be fancy.

That's what I'd do. No ground clearance issues. No need to weld on the tank. Cooler fuel. Cooler pumps. Longer service intervals.

Then, once it's working, you could add a pump controller that raises pump voltage with engine rpm and run the pumps on 6-15V depending on demand. That will also reduce heat and extend service life.

And, ebaying the A1000 will pay for all of the hard parts most likely.

Byron

[ByronRACE]

If you decide to do this "fuel module" approach, consider making a round can with a flat and thick (so it stays flat) bottom, and on the very bottom, drill a big hole (1") in the center and cover it with a disk of thin aluminum sheet metal that is smaller than the ID of the can and deburr/sand all the edges. Keep the welds on the outside of the can. Add some stops to keep the disk from being able to move vertically more than say 1/8", but leave lots of free area for fuel to flow by.

The idea is that when you submerge this can into fluid, the disk lifts and the can floods. Lift the can, and it remains full. This would make for a very simple, very slosh tolerant pickup area. That can would be at tank level regardless if you did nothing else.

I wouldn't pour your return fuel into this can; it makes it harder to keep bubbles out of your pickup stream; and if you think about it the level will remain (on average) at the same level as the tank regardless.

This isn't my invention; this is how the OEM ford fuel modules work.

The OEM modules take this one step further and use the return fuel stream to power a jet pump that lifts the fuel from the bottom of the tank (outside the module) into the module. This keeps it full to overflowing all the time; and is even better. I don't know what to recommend for a jet pump design, but if you want a real project, that would be the ultimate.

Reference: https://delphi.com/shared/pdf/ppd/pwrtrn/series7000.pdf


B

[SF_SN888KE]

Wow! Sounds complicated .... I think I might go back to a 750 double pumper! Or just stay out of the altitude, hot weather and keep the fuel tank 1/2 full! Will ponder this over the weekend at the DeAnza show.

[PANAVIA]

So Byron, where can one get a Delphi 7000>?

Steve

[ByronRACE]

Not sure where you can source that exact module, but if you browse around in the bone yards starting at around 1996, you can find all kinds of fuel modules that work exactly like that.

Buckets with flappers on the bottom that use return-fuel jet pumps to keep them full was "the thing" then...right up until they all started to get rid of the fuel pressure regulator, dead-head the delivery line, and use software to modulate the fuel pump voltage to hit the desired delivery pressure.

If you want an immediate example, 1996 Mustang GT or cobra thru 1998 for sure.

However, these designs are only good to about 300rwhp. You'd have to build your own to get more flow/fill out of them. The jet pumps are sized accordingly and if you start taking fuel out of the bucket faster than the jet pump and bottom fill orifice can accommodate, you'll run the bucket dry at WOT.

I'd like to build a jet pump bucket design like that...if I find time, I'll work on it. The simpler version...or "just a bucket with a flapper bottom" would be plenty provided you leave some fuel in the tank. The jet pump is nice because you can run the tank nearly bone dry and the bucket remains full.

[SF_SN888KE]

Byron and Mike,
Had to read your suggestions like 5 times each and then check eBay for parts and the links to figure out what you guys are talking about. (I'm a stock broker, not a mechanic!) Sounds like internal "swirl pots" and internal fuel pumps are the way to go. I'm at 600 hp at the rear wheels (TWM injection system), so which pump?
The fuel sump still sounds easier for a first try and if it doesn't work, (assusming I don't rip it off on a speed bump) I can always start cutting the top of the tank out!
Will have to think about it and figure costs and time, or drive in a cooler place. Tx.