Fuel Tanks
 

I answered a Post on Pro-Touring and thought I would add it here also...

Back in 1993 I had my first experiences with a ’69 Camaro and add on EFI fuel pumps. I bolted the pump to the frame rail added a return port to the tank and started to drive the car. As I was walking back to my house after the car quit for the 2nd time I had time to reflect on where I had gone wrong. The stock ’69 Camaro fuel pick up sock was falling apart and sending crap from in to my pump causing it to fail.

I added a pre-filter and solved that problem. I left for One Lap of America and the engine would fuel starve at anything lower than half a tank on road courses. I also blew the high pressure fuel line off the fuel pump at Michigan International Raceway and had a large fire that year. (Kyle Tucker was driving at the time and had to bail out of the car) The fuel pump I was using only had barb fittings on it. The high cornering loads at MIS caused the line to pull part way off. But not enough to kill the engine.

•Lesson 1 Stock fuel pick ups won’t work
•Lesson 2 Don’t use barb fittings

On the Red Witch I used an ATL fuel cell with a remote mounted fuel pump. It worked fine just a pain to fill at the gas station with the foam in it. It also required cutting the trunk out of the car. It would pull down to about a ¼ tank before fuel starvation.

•Lesson 3 Fuel Cells work

When I was building the Trasher I added a “Fuel Bucket” to the inside of the stock tank. The ATL (http://www.atlinc.com/catalogs.html) (Page 20 – 21) fuel bucket had 3 check balls in it and the fuel pick up. I added a sump to the rear of the tank and put the fuel bucket in it. To get access to the inside of the tank I cut an access hole in the top of the tank. I closed out the hole in the tank with an ATL tank plate and back up ring. ATL no longer sells these due to a law suit. It also always seemed to seep a little fuel after you filled the fuel tank. I think this was due to the lack of a proper vent and pressure would build up in the tank and push fuel past the gaskets.

That system worked OK. I could use the fuel down to ¼ tank on a race track. I didn’t like the idea of cutting and welding the stock tank. I lined the inside of the tank after I modified them to keep them from rusting. It was all a pain. I used something similar to this on the Mule. Both of these set up uses external Bosch fuel pumps.

I had Ricks build me a stainless steel tank for Camaro X with the check balls and a fuel bucket in the tank and a Walbro pump in the tank. It worked OK and would pull fuel down to ¼ tank on track. On this tank Rick’s still had not sorted out the vent and it would push fuel out of the tank when full. I added a vent to the filler neck that tied into the Rick’s vent and seem to reduce the problem.

•Lesson 4 Fuel Buckets work fair

When I did Jack Ass I had had years of experience with low fuel handling problems at work.

A little background. People suggested using two fuel pumps and a surge tank. This will work on a race car but will not work in production. Fuel pumps need fuel to lubricate them. Transfer pumps will work for a while dry but not very long. If you plan to use electric fuel pump to feed a surge tank then some day you will burn up your transfer pumps.

What we came up with is a fuel pump setup that sits in its own buck the fills the bucket with “jet” pumps. Jet pump are siphon pumps that use some of the fuel flow to run through an orifice to create a pressure drop to pump fuel. Many factory fuel pumps have jet pumps. Many new cars have split fuel tanks and need one jet pump to keep the bucket full and one to pull fuel from the other half of the tank. Corvettes have two tanks connected by a transfer tube and Cadillac CTS’s have saddle tanks and a transfer tube. I had Hector at Rick’s build me a split tank for a ’69 Camaro with the ring in it to allow a stock CTS-V fuel pump module. The fuel pump module sits on one half and a ½” tube runs to the other side of the tank to pick up fuel.

During the Motorstate Challenge Charley and I forgot to put fuel in JA after the road race Saturday night due to doing a photo shoot. We went to the Autocross the next day. Again we forgot to add fuel. I did my 3 runs then Charley got into the car and made two runs. Waiting to make the third run he noticed the fuel gauge "E". Charley made 1 more run on the autocross course with no fuel stumble before we could get more fuel. So the set up we have will pull the tank to empty in a heavy lateral environment.

•Lesson 5 Stock stuff works!

I went through 5 tanks from Rick’s before I got something that I feel works. I would like to thank Hector for all his help building me one off tanks. I consider this all development. There later tanks also have the vent system working much better now.

A quick note on fuel pumps. If you run a big pump for a long time at low consumption like on Hot Rod Power Tour they over heat. (ask Charley or Jody) I like stock style intake pumps with FSCMs to step down the voltage at cruise to help to not heat up the fuel.

Now the down side – none of this is cheap. Just my 2 cents…

Mark :lateral:

great info Mark, and thanks for posting.

Jody

Great Info Mark
 

Could you post up a simple sketch of how you did the CTS-V deal? If it is proprietary to you or Rick's I understand. I am in the middle of working out our fuel tank at the moment. It will feed an EFI Wegner LS415. I have been doing research and then you post this here. Great timing. Anymore detail would be greatly appreciated. Thanks very much!

Thanks for sharing your knowledge Mark. I always try to do the same. :thumbsup:

Jody,

I remember reading that you thought the fuel heating problem you had on PT with the yellow Chevelle was due to running the fuel thru the hot engine compartment.

I set mine up with the regulator at the rear bypassing immediately to the tank. I have a Walbro 255 in a Rick's tank. I hope I don't run into any pump overheating problems as I plan to drive out to Columbus next summer (about 7 hours for me.)

Thoughts? Mark, Jody, Bueller, anyone?

the fuel returning from the front mounted regulator was smoking hot due to a variety of reasons I'd guess; much bigger pump than required (A1000 Aeromotive), no pump controller to slow it down, fuel rails and engine compartment heating the rails, lines, and regulator, chrome plated intake and rails, etc. If you bypass at the rear it's not likely that the fuel will get warmed much at all. Mine is that way, and after driving 150 miles to Hot August Nights last year the stainless tank wasn't even warm.

Jody

I too would love to see a sketch of your solution Mark and Thanks for the info !

Jim

I asked first! :P How's that German Vette coming?

Okay -- Now I'm really confused!

I thought the whole purpose of having a bypass regulator was that the fuel was returning to the tank "continuously" -- keeping the pump running fuel - thus cooling it - and the large tank (in my case - 25 gallons) helping to act like a heat sink and cool the fuel.

I'm running the Aeromotive 1000 - externally - with an Aeromotive by-pass regulator.... I do not run a pump controller... it's just run by the Accel Gen 7... Fuel pump lead to a relay...

Are you saying that my fuel is getting "smoking hot" by the time it returns to the tank - and that I could have an overheating fuel pump??

where is the regulator?

Regulator is mounted on the firewall.

Is your regulator before or after the fuel rails? You'll get some heating of the fuel by going into the engine compartment, but probably not as much as going through the rails. We were fine for about 100 miles of steady driving. By 125-150 miles it had heated the fuel in the tank enough that the fuel pressure was dropping, pump was getting real loud due to aeration of the fuel from the heat. On Power Tour there were several other cars stuck on the side of the road or fighting the same symptoms. Most were not brand new builds, and had not ever had the issue before; but they had also never been driving 200-300 miles per day like you do on the Tour, so the short trips around town will probably never shows the issue.

Jody

Regulator is after the fuel rails -- so the fuel is fed to the front of the passenger rail - out the back - looped to the front driver rail - out the back to the regulator mounted on the firewall - where it returns to the tank.

I ASSumed the fuel was moving continuously through the system... only "stopping" / or "slowing" as required to build pressure (the regulator - doing it's job ala a thermostat on the coolant side of things).

If the pump is whirring away without any fuel movement -- then wouldn't we have another issue --- CAVITATION?

Here's pix of the rails etc as I plumbed them.... no comments from BENT about my work please!!!




http://i919.photobucket.com/albums/a...rtStack002.jpg







I pulled the other pic off there - it's too blury to post... and didn't add much anyway.

although the stainless hard lines and braided lines look good they do act like a heat sink. The fuel is moving through the system, but getting heated quite a bit in the hard lines and rails.

Usually if you enter in the front then you'd use a short line from rear of one rail to the other and exit in the front also (opposite rail you entered). So if you wanted the regulator hidden in the rear then enter in the rear also. Your way works, just adds even more stainless hard line to heat the fuel though. Bottom line, if you're not having problems with the fuel pressure dropping on long runs you should be fine. Large pumps aggravate the situation, but you do have some of the ingredients of the problem scenario with all the hard lines and front mounted regulator.

Not sure what you meant by the cavitation issue....... were you speaking of a rear mounted regulator? In that case the regulator still bypasses to the tank, just at the rear of the car, not the front. Still fuel moving through the pump like your setup, but without the hot fuel back to the tank. If you want to see if you might have an issue you need to take a 100-150 mile drive down the freeway, watch the fuel pressure, or pull over and feel the tank. If the fuel is heating the tank you'll know it, the tank will be hot to the touch. There are tons of cars with front mounted regulators that have no problems, it just takes the right combo of parts and conditions to cause the issues we had. Big pumps running full speed, hard lines and rails heating the fuel, long runs, etc. I've been mounting the regulators in the rear for years without any issues. Many people have said you can't do that, I don't argue with them. I know the later Vettes, GTO's, etc. all had the regulator in the filter on the frame rail, with the bypass off of that, only one line to the front and work fine. They do bump the fuel pressure, probably to help guard against any fuel boiling from the fuel in the rails; I've run from 43 to 58 psi at idle, never seemed to make any difference, no problem either way.

Jody

Cavitation is what happens to liquids when they're being pumped but not moving... so it "stirs" bubbles in the liquid...

Think of it as your tires spinning -- it looks great but you're going nowhere...LOL

I was thinking that if the fuel was not moving continuously - that you'd have TWO issues -- no movement leads to pump heating up - and if you toss in cavitation - caused by a pump that is "spinning it's wheels" - then you're also going to loose pressure - since we know bubbles don't move like liquid (ala air in a brake line)

Jody --

I HAD to run the lines the way I did -- because the intake is so tight to the distributor...

I originally wanted to feed the rear pass side -- loop the front - and out the driver rear... just couldn't get 'er done that way and be able to hook it up etc.

The way I had to go was to install the motor - and then just be able to hook up the front feed... as the looping could be built and set up "on the bench".

As it is - to stab the distributor - the rear passenger side TB's have to come off... It's REAL tight back there! Real tight.

In what situation is the fuel not moving continuously through the pump?

Jody --

Maybe I'm just not trackin'

I guess what I'm trying to find out is -- why would the fuel be heating up - if it's always moving throught the system (as it should be) then it should be cooling off - even assuming it's being heated a bit while in the rails - It's got a return trip via SS lines (heat should be dissipating) - back to a fuel tank that should also be dissipating the heat - given the volume in the tank vs the volume in the return line...

So I guess where I'm lost is -- the fuel pump overheating... Or maybe I need to go re-read what Mark was saying? I may have misunderstood the whole thread!! LOL -- It wouldn't be the first time!! :cool:

let me say this, and see if it makes sense. I don't think you realize how much those rails, stainless lines, and engine compartment can heat the fuel before it's returned. On that Chevelle where Scott and I made the ice bucket solution for the return fuel, just to finish the Power Tour, the returning fuel was so hot that you could not touch the copper line in the trunk at the inlet to the ice chest. It actually was melting the ice chest................... The other thing was the too large A1000 pump running full blast without a controller to slow it down; that heats the fuel some also.

Jody

I only have this to say....

HOLLY CRAP!!


Okay -- First thing after SEMA - I'm going hunting for ANY fuel issues like this! Between now and then I will be sleepless in Seattle...

Thank goodness it's winter here - and I have time between now and Power Tour to modify.

Maybe we'll get a chance to talk at SEMA and I'll get a better idea of what I'll need to do -- and order a new Ricks Tank or whatever (I currently have a SS version from Rock Valley).

I'm amazed some propeller-head aircraft engineer didn't use a jet pump in an automotive situation long ago - aircraft have been using jet pumps in their tanks for over 40 years. Ours serve 2 purposes - 1 is to get all the fuel in the tank and sump areas (we use several due to all the low spots in tanks) - and 2 is to mix all the fuel and water :( in the tank so the water always stays suspended in the fuel and burn.

So that got me thinking, does anyone use aircraft style tank flapper doors to control fuel slosh in the different chambers of Lat/PT style street fuel tank ?

I've looked at many fuel cells being built for street type cars and they just use partial walls with holes or passages to restrict the fuel during laterals. In aircraft tanks we use a flapper style one way blockoff that closes over the opening in the the dividers/passages.

Example: the inboard tanks (against the fuselage) are where the pumps live. The outboard tanks usually gravity feed through holes in the tank walls into the inboard tank to eliminate extra pumps and tubing. But, the flapper valves close when the aircraft changes attitude to stop fuel migration back to the outboard tanks.

I wonder why we haven't used those aircraft parts to control fuel levels in a 'sump' area of our street tanks to control migration and sump starvation ? Or have I missed it and someone already does use them ??

I can post up an illustration of the aircraft valves if someone wants to see them.

Jim

I wouldn't worry until you figure out if you even have a problem............... :) Would be worthwhile to take a trip and see how it goes, even more so if the weather was warm like Power Tour.

Jim,

you up for a science project? We both need fuel tanks and we are not that far apart! We both have ideas, I have Solidworks and a fantastic welder friend! I'm game if you are!

Hi Chad !

I don't have the final size of my tank yet - but I'd be glad to do whatever I can to help figure out a design concept that we could use. Hopefully others on the site could lend some design ideas and experience too.

PS, your truck is looking great and you're making good progress !!! :thumbsup:

Jim

Thanks Jim. Maybe we will make it a class project. I am happy to model some ideas and see what we can come up with. We can post the progress. We'll see if we get any other input.

I built this one... but it's OLD SKOOL like Garage Dog was saying -- just some baffles with holes... I LOVE the slosh door idea... where the sump could fill but not empty...




http://i919.photobucket.com/albums/a...k/IMG_0946.jpg




The TIG welding sucks --- One of these days I'll get the hang of it!

But check out that MIRROR POLISH!!! EEEEEEEHHHHHHHHHHAAAAAAAAAA!!!





http://i919.photobucket.com/albums/a...k/IMG_0956.jpg

This is NOT for you "track stars" -- this metal is so shiny it's beyond ridiculous!!!



http://i919.photobucket.com/albums/a...k/IMG_0950.jpg

I'll be watching for your post on the baffle design. Very interesting.

X's 2 -- 'cause I have to build another fuel tank soon -- and I'd love to see what kind of baffles etc...

I'm thinking (which is a bad thing!) that they'd be "similar" to the baffles used in an oil pan... a simple hinge pin - and trap doors... with a compartment in the rear - center of the tank?? So the fuel would be "contained" there... with the fuel pump and or pickup in that compartment.

Mark ---

What is this -------> FSCMs <------

You reference this in your original post -- and I can't come up with a suitable "name" -- something something Control Module??

I'm running a SPAL PWM fan controller - is this something "similar" where it really doesn't drop the voltage to the pump but rather Pulse Width Modulates the motor?

Sorry I'm so dense....

You got it Greg !

It's a compartment with a lowered floor that has the sump pickup for the pump and it's surrounded by walls. In the walls, down by the lower flange are the transfer holes (just like the tank dividers you made - just lower the round holes all the way down to the flange) - but there's no other access for the fuel to move. The flapper connects on the compartment side that has the sump by 2 bolts so the fuel flows in by gravity and/or lateral forces - but not back out.

It was patented in 1941. Pretty simple device so I’m sure someone is using it. Here's a pic.

Beautiful work on your tank Greg - I'd be proud to have something like that ! And yes, it is shiny !!!

Jim

Fuel System .......... I think

FSCM (Fuel System Control Module) used to step down the voltage to the fuel pump.

Sorry for the confusion

Mark

you friggin' engineers.................... :lol:

Thank you Jody!! My thinkin' egg zackedetly

LOL

Okay - found the controller at Aeromotive website -- nice little billet jobbie. Seems they only make ONE - so that's REAL EASY... I'll add this to my system - and then check the fuel temps as soon as we "thaw out" here in the Pacific NorthWet.

I'll be certain to have this all redone before Power Tour. Damned if I'm going to have you guys flipping me off as I sit on the shoulder.... steam rolling out the front - one tire shot - A/C blowed up... Tailgate draggin'.... tools spread out for half a mile...


:>)

wow, some awesome info in this thread for sure!!

Does anybody have any sort of link, or any way they can lead me to more information about or a source automotive jet pumps? I've tried to hunt down info on the 'vette and the cts-v setup and am getting nowhere...Seems like a jet pump might be a wiser way to do a surge tank (albeit still not as wise as an internal setup).

So it seems at Mark has done all the R&D for perfect tank .. and Ricks- Hector can build one. So why they dont offer us one at the first place ?

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Take this for what it is worth -

It's been awhile since my Fluid Dynamics classes back in school, but I just thought I'd chime in (and probably confuse things and myself in the process).

Cavitation occurs when the pressure of the liquid drops below the vapor pressure of that liquid at a given temperature, essentially boiling. The creation of these "bubble" and their collapse causes little shockwaves inside the pump, causing vibrations and can cause the impeller to pit/break etc.

This Wikipedia entry was helpful in refreshing my memory and/or relearning.

http://en.wikipedia.org/wiki/Cavitation

I'm guessing that what is being seen in these applications is discharge cavitation - caused by too high pressure at the exit of the pump, caused by restrictions. The rule of thumb that I saw in the Wiki entry was this is likely to occur when the pump is running below 10% of it's most efficient point - not sure how accurate that is, but it may be a good rule of thumb.

I'm not sure that this helps or how practical any of this is, but it may help explain some of what is going on.

On another note, it was mentioned that running the regulator at the tank required running a higher pressure to get the needed pressure at the fuel rail. That would be expected as you will see a pressure drop proportional to the length of the pipe run. I think Bernoullis Principle is used to figure this out, but more practically, just measure it and adjust accordingly.

OK - I'm done rambling about stuff I used to know about...............


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The Fuel System Control Module sounds like the way to go. I've yet to build anything that makes enough power for this to be an issue!!!! Maybe one day!

Mark, what controls the FSCM? What does it use as a reference to adjust the voltage? Is it controlled by several factors from the ECM - like load, throttle position etc.?

Brandon --

The Aeromotive version takes a TACH input...

It's pretty simple wiring - Ignition - power - tach.