22 gallon cell starving at ~12 gallons even with giant Hydramat - What am I missing?

mad_science said:

Time for my bi-yearly update on this thread after our weekend at Thunderhill.

TL;DR: did a bunch of cleanup, still cuts out at ~10 gallons left.

The upgrades: moved the pump into the tank, lying on its side for maximum immersion in fuel and minimum suction pressure head needed. Lines are 1-piece metal from rear axle to engine bay, placed in thermal sleeve and tucked up into driveshaft tunnel to block radiant heat from exhaust. We should have addressed pump "pulling" fuel and fuel heating.

...but it still cuts out on hard turns at 12 gallons used. It's definitely inertial.

Conclusion: my giant ass hydramat isn't performing as advertised. It covers the bottom of the cell, so should still have fuel on it with 10 gallons left, and it's definitely sucking air.

Next plan is to move to the puck pickups in all 4 corners like this setup, except with the pump in the tank.

Will try to test it with 1 gallon in the tank with the car at an angle or whatever to see what we get.

Will report back eventually...

We went from a hydramat to pucks and still had similar issues. Tried pucks plus tank foam, still had issues (always at 12 gallons used in a 17 gallon tank). Got the best results from baffles and a surge tank; however, we still are getting serious fuel starvation after 12 gallons but doesn't cut as bad as it used to. I'm thinking it's boiling hot gas from the return. 

In reply to DirtyBird222 :

Is your starvation inertia related? Ours only cuts out on right turns.

Could the hose running from the Hydromat to whatever it connects to be loose or have a pinhole in it? Either would cause the problem, where it works fine as long as it's covered, but sucks in air when uncovered.

kb58 said:

Could the hose running from the Hydromat to whatever it connects to be loose or have a pinhole in it? Either would cause the problem, where it works fine as long as it's covered, but sucks in air when uncovered.

Definitely worth checking, as that also matches the symptoms.

My 68 Mustang Street/Autocross car with FAST efi suffered fuel pick up problems with a stock type 22 gal tank,first with a Tanks Inc intake pump and (too) small fuel tray. Next Aeromotives stealth setup had me good at more than 1/2 tank but in autocross less than 1/2 had it cutting out.The fix,Aeromotives Stealth check balls, autocross no pickup problems below 1/2 tank (never raced with less than 10 gals. On the street I ran it out of gas and coasted into a station and put 22.2 gals in my 22 gal tank.

My point?

Intank pump in a sump at least 1/2 as high as the tank with anti over flow lip facing in.

one way check valves at the bottom sides of sump to let fuel in but not out.

Aeromotive has a fuel cell intank set up now,you may have to call to get the check valves.

In reply to mad_science :

I have a smaller hydramat in a stock tank. After fighting similar issues for years I've gone to a surge tank. 

Simple surge tank fed from stock tank by an electric carb pump mounted as close to and below the tank as possible. EFI pump gets fed from the surge tank and retuns to it. Surge tank has fitting at the very top that returns to stock tank. Its been a good change so far.

Surge tanks solve all these issues.  They are cheap and not many failure points.

It's just 1 pump and an aluminum tank.

I think we have all gone through this exact process.  

Not related to your fuel feed issue, but it seems like running the fuel line in the tunnel next to the driveshaft is kind of risky. What happens if you break a U-joint, and the driveshaft starts flailing around inside the tunnel? A fire seem likely to me.

Alas, external surge tanks are prohibited.

Barring my in-tank fittings sucking air, it's currently a toss-up between a 4-corner puck system or an internal trap door surge tank.

mad_science said:

Alas, external surge tanks are prohibited.

Barring my in-tank fittings sucking air, it's currently a toss-up between a 4-corner puck system or an internal trap door surge tank.

Lemons, right?  We ran one for about 6 years.

Ya just gotta make it look like a large fuel filter...  in fact, that's what we used for our surge tank.  A large fuel filter and mount.  We just added a long tube that went to the bottom of the filter as the pickup.  It also allowed us to get rid of the other fuel filter 

Edit...  looks like they started cracking down on the big fuel filter trick...

I'd try to run an in tank surge tank if possible.

Damn we just ran a surge tank at lemons sebring. It does look like a catch can though. 

There are surge tanks that mount to the oval hole of an ATL fuel cell which would be inside of the cell and should meet Lemons rules.  Radium makes one.  Lift pump to feed the surge tank, then one or two pumps in the surge tank.  

I built a custom fuel tank from scratch for Midlana. The tank was divided into three sections, each tapering to a one-way flapper valve into an in-tank accumulator. Inside was the main fuel pump, and fuel returning from the fuel rail dumped back into the accumulator section. Zero problems, ever.

wvumtnbkr said:

mad_science said:

Alas, external surge tanks are prohibited.

Barring my in-tank fittings sucking air, it's currently a toss-up between a 4-corner puck system or an internal trap door surge tank.

Lemons, right?  We ran one for about 6 years.

Ya just gotta make it look like a large fuel filter...  in fact, that's what we used for our surge tank.  A large fuel filter and mount.  We just added a long tube that went to the bottom of the filter as the pickup.  It also allowed us to get rid of the other fuel filter 

 

Edit...  looks like they started cracking down on the big fuel filter trick...

 

I'd try to run an in tank surge tank if possible.

Hmmmmm...

I mean, since I need an in-line fuel filter anyway, running this monstrosity:

https://www2.wixfilters.com/Lookup/PartDetails.aspx?Part=100055

on a remote fuel filter housing is functionally a surge tank. It holds about a half gallon of fuel.

mad_science said:

Take this with a grain of salt. 

You need to baffle or bladder your tank. There is too much room for movement. The 4 pickup system will only help as much as the mat, which was minimal. 

Personally, I would run two pumps, a pair of pickups diagonal from each other and have the pickups set in a small well in each corner. Maybe a simple divider system made of angle that does not allow the fuel to run away quickly, shaped like a tic tac toe grid about 2" high.

mad_science said:

wvumtnbkr said:

mad_science said:

Alas, external surge tanks are prohibited.

Barring my in-tank fittings sucking air, it's currently a toss-up between a 4-corner puck system or an internal trap door surge tank.

Lemons, right?  We ran one for about 6 years.

Ya just gotta make it look like a large fuel filter...  in fact, that's what we used for our surge tank.  A large fuel filter and mount.  We just added a long tube that went to the bottom of the filter as the pickup.  It also allowed us to get rid of the other fuel filter 

 

Edit...  looks like they started cracking down on the big fuel filter trick...

 

I'd try to run an in tank surge tank if possible.

Hmmmmm...

I mean, since I need an in-line fuel filter anyway, running this monstrosity:

https://www2.wixfilters.com/Lookup/PartDetails.aspx?Part=100055

on a remote fuel filter housing is functionally a surge tank. It holds about a half gallon of fuel.

Just put a hose / tube to the bottom of the filter.  Otherwise it won't really work as a surge tank.  Also needs a fuel pump after the filter.

I found this thread while researching the fuel issue on my lemons car. I'm also running a 22-gallon cell with a Hydramat that covers the whole bottom. I can use about 15 gallons of fuel but after that, I still get fuel cut in corners and elevation change. I'm also running an in-tank pump as well. 

I called Holley but they were not much help and said they have never heard of it having this issue. The only thing they told me to try was to run it without foam. Our cell has a bunch of foam and I guess it is putting a fair amount of pressure on the mat. I don't want to remove all of it but I'm going to try and pull a few pieces for the next race and see if that helps. 

The mat also has 3 pickup points. Currently, the pump is connected to the middle one but I'm thinking of hooking all three up and tee them into the pump. 

Here was my stainless tank during construction. Top pic shows the general layout, with the three things standing on edge being the one-way flap doors. The lines show where the wall dividers go. They serve multiple functions: stiffening the final assembly, guide the fuel toward the rectangular accumulator section, and prevent sloshing. Second pic with dividers in place. Return fuel is fed back into the accumulator. Zero problem, ever.

In reply to PseudoSport (Forum Supporter) :

PseudoSport any resolution to your problem?  I'm having the same problem w/ my fuell cell and hyrdarmat as I'm running in Champcar.  I've got the same situation where my hydramat covers the whole bottom of the cell but I end up missing a few gallons from it when on track.

I learned recently that Hydramats are consumables.  A friend had one in their 22 gal cell, couldn't get nearly full capacity.  They took it out, it was all dirty, put a new one in and were suddenly able to just almost all of their capacity again.  

jsflanagan said:

In reply to PseudoSport (Forum Supporter) :

PseudoSport any resolution to your problem?  I'm having the same problem w/ my fuell cell and hyrdarmat as I'm running in Champcar.  I've got the same situation where my hydramat covers the whole bottom of the cell but I end up missing a few gallons from it when on track.

If running in champcar, just put a surge tank in.  You just need a second pump to feed the engine.  It's like a 40$ aluminum tank and a fuel pump.  It WILL get everything out of the tank to the point that when your car sputters, you better be in pit lane!

Do you have the ability to run a drop in pump/basket? It's a pretty simple solution with the integrated baffling and valves.

In reply to Shavarsh :

To be honest, I am shocked if drop in units don't already exist for common fuel cell layouts.

This type is essentially a built in surge tank with a trapdoor on the bottom.  OEs use these in unbaffled plastic tanks to get every drop of fuel out under all conditions.

If Hydramats are consumables, that's an awfully expensive consumable!

Sonic said:

I learned recently that Hydramats are consumables.  A friend had one in their 22 gal cell, couldn't get nearly full capacity.  They took it out, it was all dirty, put a new one in and were suddenly able to just almost all of their capacity again.  

Oh damn

Prepping for upcoming Buttonwillow, so we cracked open the cell to check things out.

• Had about 2 gallons in a 22 gallon cell
• Tilted car away from the port side of the hydramat as high as my jack would lift.
• Had maybe 1/3 of hydramat covered in fuel, 2/3 dry.
• Ran things with the cell open to see if we're getting bubbles.
• Confirmed the hydramat fittings between it and the pump were not sucking air when exposed.
• No bubbles, no sputtering of the motor, nothing. Working as it should.

And to remind people, the symptoms are: at ~1/2 tank (11 gal), the motor starts to cut out on right turns. Only right turns, and comes right back when straight. It's very inertia-driven.

We had 2 engineers and a physicist looking at this thing this afternoon utterly stumped...so, uh...wut now?

Thoughts:

• Maybe we fixed it by messing with it this afternoon? Unlikely.
• There's some dynamic element to it: like the pump + mat + foam are somewhow all sliding to one side and causing a pinch or kink? But why only at 1/2 tank? Also, tried to move things around in there by hand, nothing wants to budge.
• We're not really drawing a lot of load to consume a lot of fuel to duplicate it? But it's a return-style efi, so I think it always draws the same volume and just returns what's not used by the injectors? We were dumping the return into a gas can to further deplete the available fuel and it was pumping a high volume.
• Maybe our problem requires heat build up from racing? I don't see how an inertial problem could come from having hot fuel, but dunno (shrug). We weren't about to break out the heat gun on an open box of gas.

Ultimately I think my (Lemons rules legal) options look like:

• Do nothing and be annoyed but not surprised when it cuts out early again. I don't like this option but it's cheap.
• Swap hydramat for 4-puck system. I'm skeptical because those work basically the same way a hydramat does (shut off when not in fuel), and I talked to at least one vendor who quit doing those to move to hydramats instead. Only thing would be if this change is enough to stop the unknown source of our problem.
• DIY or buy an in-tank passive surge tank/box with check valves and put the pickup inside
• DIY an in-tank surge tank/box with a lift pump
• Fork out like $1500 for a Radium FCST unit or similar from DeatschWerks and be done with it.

As an aside on the "complete unit" solutions: I also have to re-do our filler setup b/c it was deemed us standing in the truck bed to refill was unsafe. I already have the pile of ATL parts of that, none of which are compatible with the modular surge tanks above.