I've got a 22gal ATL cell in my Lemons Ranchero.
Originally it was cutting out with 12 gallons left with the stock pickup in use.
I was able to snag a giant Hydramat from Holley for a steal a few months back. I thought our problems were over, but seems like we only gained a couple more gallons of usable cell.
I'm perplexed, as that mat covers like 85% of the bottom of the cell and hydramat is supposed to be able to slurp to the last drop.
...what am I missing here? Could the cell foam be compressing the mat or something? My fuel gauge sender is pinning it to the bottom of the tank, hopefully hasn't damaged it.
There are a couple of things I know are working against us:
- The cell is wide side-to-side, leaving potential for maximum lateral slosh
- The cell is tilted down in the front. I installed it square to the bed, but kinda neglected that the whole cartruck sits very nose-down. Would've been better to tilt down in the rear to keep the fuel in one spot while accelerating.
Pictures for reference:
Are you running mechanical or electric fuel pumps? If electric, how many?
maybe a venting issue not allowing the pump to suck fuel out once it reaches that level?
AngryCorvair (Forum Supporter) said:
maybe a venting issue not allowing the pump to suck fuel out once it reaches that level?
This would be my guess as well. Can you rig up a temporary vent to find out?
BTW, your pictures are a no show.
To test the venting question you could stop and open the cell. If there is a noticeable suction release then the venting is not right. If there is nothing noticable, then try to start it back up with after closing the cell and see if the problem persists, without adding fuel. There should be a vent in the lid or a roll over vent to the top of the can.
Pics aren't coming through but what fuel pump are you using? Some are particularly bad at suction. Agreed on the venting questions.
Any length of hose between the hydramat and the pickup? Or the pickup and the pump, or the pump and the tank outlet? I had an issue where a block of wood hit the bottom of my fuel tank and dislodged the pickup. That caused the hose between the pump and tank outlet to kink. Would start and idle just fine, but would not maintain pressure at anything higher than 2K rpm, just suck the supply hose shut at the kink. Only noticed it when reinstalling a third(!) fuel pump because I thought the first two had gone bad somehow. Cut the hose shorter and no more issues. Check your plumbing inside the tank.
Does this pic work?
Fuel pump is whatever electric inline comes with a Holley Sniper 2bbl master system, believe it's this 80gph inline. It's mounted ~20" of hose away, along the frame rail forward of the cell. Roughly even with the bottom of the cell, but I could/should double check that height.
Fuel line inside the cell comes from the -10 AN fitting on the driver's side of the hydramat up to a -8 bulkhead through the cell's top plate and is either 1/2" or 3/8" line to the fuel pump. 3/8" from pump to Sniper. No fuel filter between hydramat and pump because the hydramat works as a 10um filter according to Holley.
Cell has a vent line that goes down the back of the outside of the cell and has a loop in it. I can double check it's not too high (?) or pinched or whatever.
The fuel cut out is primarily inertial, where after certain turns or elevation changes (was just at Buttonwillow) it starves at/after corner exit. Drives fine in a straight line, etc.
That last bit of information definitely sound like the pickup is getting air. You may want to try adding baffles to split the tank in thirds left to right. A simple flat sheet of material that is plastic and fuel resistant would do the trick. Lock them in place with the fuel cell foam and leave some small notches at the bottom edges to allow the flow to settle when not cornering.
So you have the fuel pump mounted outside the cell and it's lifting the fuel out of the tank through the hydramat? Likely the problem, you need the pump IN the cell or get a pump with some suction capability. It only works when the fuel level is higher as you have some head pressure from the fuel giving the inlet of the pump some hydraulic help.
If I relocate my external pump to be as close as possible and below the bottom of the cell, that should address the issue?
...or would it make more sense to put an in-tank lift pump to feed the external? (could this be lower pressure than my external?)
...or would it make more sense to just redo everthing with an in-tank pump that does everything?
I'd think re-doing everything with an in-tank setup should be worth it, that will give you the simplest and most reliable setup overall, and with the hydramat you should get zero fuel starvation with that setup.
stafford1500 said:
That last bit of information definitely sound like the pickup is getting air. You may want to try adding baffles to split the tank in thirds left to right. A simple flat sheet of material that is plastic and fuel resistant would do the trick. Lock them in place with the fuel cell foam and leave some small notches at the bottom edges to allow the flow to settle when not cornering.
This would be my guess as well. If baffles don't help possibly damage to the line from the hydromat that sucks air once it's above fuel level. Been there, chased it for an embarrassing period of time.
GameboyRMH said:
I'd think re-doing everything with an in-tank setup should be worth it, that will give you the simplest and most reliable setup overall, and with the hydramat you should get zero fuel starvation with that setup.
My vote as well. I know some people pull fuel out of a tank but it's usually with a burly fuel pump (Weldon, etc)
Where's the exhaust????
I discovered on my car that I get "fuel starve" problems when heat builds up under the car and it basically (my guess) starts boiling or at least creating bubbles by the time it gets to the injectors.
A simple heat shield between the exhaust and external fuel pump fixed a lot of the issue. But in the past I've had heat buildup in the tank enough to "add" fuel volume in the tank until it leaked out the cap. Gallons worth of volume mine you...
We are having a fueling issue with our endurance car, too. It seems that the rubber intake hose is getting too soft after sitting in the hot tank of fuel for 8 hours, and collapsing. The tank doesn't drain over the 2 hour stints between refuel, and we are only refueling about 8 to 9 gallons of the tank (about half the capacity). The returning fuel is hot . . . and the tank is also near the exhaust, so nothing seems to cool down. The new fuel we add doesn't cool the tank enough, maybe?
We are going to try and replace the rubber gas line with a steel line and see if that addresses it. Maybe something similar is happening with yours?
In reply to ZOO (Forum Supporter) :
It's easy to hook up a fuel cooler on the return side, often generic PS/AT coolers can work.
I'm skeptical on fuel heating as the exhaust exits out the side, just behind the door. Fuel lines under car are like 6-10" away from exhaust for the run under the cab floor, but far away in the engine bay or near the cell.
More pictures:
(uploading from phone, so apologies if it gets weird)
gsettle
New Reader
10/6/23 10:11 a.m.
I know it adds complexity and more failure points, but I made a fuel surge tank that fixed my issue. The tank is made from an old Bunn coffee maker tank and is 3 quart capacity. Added a Quantum external 380 LPH (i think) pump to feed fuel rail. No fuel starve since install.
I fought a similar issue with a street car for a long time. No amount of venting, lowering the external pump, or heat shielding helped.
I ended up resolving the issue with a vaporworx system. It wasn't cheap, but it absolutely works.
If I had a good packaging solution I would have been interested in a surge tank like gsettle suggested.
I bet it's getting cooked in those lines running up the middle between the pipes.
You'd be amazed how much heat builds up under a vehicle
Any thought to replace the one big mat with 2 smaller ones in either end of the cell with a Y in the tubing? Never run a fuel cell, so IDK if that's crazy talk, but if the fuel is going to the ends, pick it up there?
In reply to 4cylndrfury :
I would think that would mean the pump would be more likely to pick up air, not less likely. You'd need two pumps that feed a surge tank that feeds the pump that goes to the engine.
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...
I've got a wide, flat fuel cell in my europa, and I added in a surge tank to keep it from starving and its done well so far. It does add complexity to the plumbing, though
