Fuel tank mod

[hoveringuy]

Tell me again why a driver side pump is required?

I get that the jet pump is the "normal" way for fuel to transfer left to right, but I'm thinking freeway cruising there.

On the track, isn't fuel constantly being transferred back and forth with cornering?

I just can't believe that more than a 1/2 gallon could get stranded on the driver side in hard cornering

[redneckvtek]

Tell me again why a driver side pump is required?

I get that the jet pump is the "normal" way for fuel to transfer left to right, but I'm thinking freeway cruising there.

On the track, isn't fuel constantly being transferred back and forth with cornering?

I just can't believe that more than a 1/2 gallon could get stranded on the driver side in hard cornering

Because when you take a hard right hand turn all of the fuel sloshes to the driver side. If there is no fuel pump there, you get no fuel to the engine after a few seconds. Usually the car makes it around the turn and then stumbles just as you are flooring it to leave the area.

2 pumps with normal pickup socks isn't perfect (it leaves about 1/2 gallon in each side, less in the passenger side because the stock fuel bowl helps).
2 pumps with hydramats is as good as it gets. Pints left.

[hoveringuy]

Because when you take a hard right hand turn all of the fuel sloshes to the driver side. If there is no fuel pump there, you get no fuel to the engine after a few seconds. Usually the car makes it around the turn and then stumbles just as you are flooring it to leave the area.

2 pumps with normal pickup socks isn't perfect (it leaves about 1/2 gallon in each side, less in the passenger side because the stock fuel bowl helps).
2 pumps with hydramats is as good as it gets. Pints left.

Right, but I'm looking at doing an in-tank surge tank on the passenger side (should have mentioned that to start...). Something similar to the one pictures, which was for RX-7. I'm guessing that all the fuel would eventually make it to the pax side.

I guess I'm thinking that this has much less chance of getting any air in the line, where the dual-pump (passenger and driver side) would still be susceptible to sucking air?

[hoveringuy]

Because when you take a hard right hand turn all of the fuel sloshes to the driver side. If there is no fuel pump there, you get no fuel to the engine after a few seconds. Usually the car makes it around the turn and then stumbles just as you are flooring it to leave the area.

2 pumps with normal pickup socks isn't perfect (it leaves about 1/2 gallon in each side, less in the passenger side because the stock fuel bowl helps).
2 pumps with hydramats is as good as it gets. Pints left.

and a follow-up question... Holley Hydramat looks too good to be true, but that's science. Can the late model level sender and pump combo be dropped on the drivers side and T'd into the pressure line to replace just the level sender? Assuming both pumps had hydramat and good check valves it would keep air out and pressure in.

[redneckvtek]

I describe that setup in post #57 of this thread. Yes the late model sender/pump hanger combo fits directly in the driver side in place of the sender only assembly. It sucks to install in the car but it can be done.

That in tank surge setup looks nice but the tank inlet on a e30 tank is tiny (57mm irrc) and welding to a galvanized fuel tank is all sorts of sketch so I would not recommend.

I won many enduro events with the dual hi-pressure pump setup feeding directly to the rail. At first with no hydra mat, then with hydramat added.

Now I run low pressure lift pumps (with hydramats) to a external surge plus reserve setup which gives more warning of fuel being out and the ability to make it back to the pits instead of the zero-warning the hydramats give you.

[AndryBismarck]

^^ yup

i'm in the making of an accumulator type tank with my current high pressure intank pump inside. I will replace the intank pump with a low(er) pressure, high volume pump such to keep the accumulator tank always filled and the high pressure pump always submerged completely (cools it too). This is probably the closest thing to actually having a fuel cell. I think this is the best solution our cars will see.

I can still see starving with that setup. definetly less, but its 'not a wow that's the ticket!!' kind of thing.

I'am just at the stage of installing a double-pump pump, it feeds a small expansion tank, which then feeds the high-pressure pump. But, I faced the problem that the wall work tank when using a small fuel cell with a capacity of 1-2 gallons, it requires the manufacture of a sealed rear bulkhead for safety. It was possible to replace the fuel cell, of course, but I saw the prices! And it is very difficult to mount because it can pose a security threat outside the cell shell.

[hoveringuy]

I describe that setup in post #57 of this thread. Yes the late model sender/pump hanger combo fits directly in the driver side in place of the sender only assembly. It sucks to install in the car but it can be done.

That in tank surge setup looks nice but the tank inlet on a e30 tank is tiny (57mm irrc) and welding to a galvanized fuel tank is all sorts of sketch so I would not recommend.

I won many enduro events with the dual hi-pressure pump setup feeding directly to the rail. At first with no hydra mat, then with hydramat added.

Now I run low pressure lift pumps (with hydramats) to a external surge plus reserve setup which gives more warning of fuel being out and the ability to make it back to the pits instead of the zero-warning the hydramats give you.

Yes, I saw that a slight modification of the mounting tangs will let the pax side unit fit. Some additional questions...

-Is the bowl depth the same between sides?
-Do both level sending units work interchangeably? (I know they have different form factors, but does it work correctly to have two pax side units?)
-You used the 3x8 hydramat with 11mm inlet?
-Any indications of sucking air? That is the biggest thing that worries me because it can damage the engine. Is it really the magic that it appears to be?

I'm not concerned about getting down to the very last gallon, I just have issues on right-hand sweepers below 1/2 tank.

One other detail. I'm running an N52 engine with the IVM unit in the rear side panel (it's a coupe), so my fuel wiring goes from battery---) straight to the IVM ----) the pump. I'm not sure if the IVM is spec'd to carry the load of two pumps, may need to run an intermediate relay to be safe. Any insight, anyone?

[redneckvtek]

Yes, I saw that a slight modification of the mounting tangs will let the pax side unit fit. Some additional questions...

-Is the bowl depth the same between sides?
-Do both level sending units work interchangeably? (I know they have different form factors, but does it work correctly to have two pax side units?)
-You used the 3x8 hydramat with 11mm inlet?
-Any indications of sucking air? That is the biggest thing that worries me because it can damage the engine. Is it really the magic that it appears to be?

I'm not concerned about getting down to the very last gallon, I just have issues on right-hand sweepers below 1/2 tank.

One other detail. I'm running an N52 engine with the IVM unit in the rear side panel (it's a coupe), so my fuel wiring goes from battery---) straight to the IVM ----) the pump. I'm not sure if the IVM is spec'd to carry the load of two pumps, may need to run an intermediate relay to be safe. Any insight, anyone?

Bowl depth is close enough. You may have to adjust slightly for the hydramat. There is no bowl in the driver side. (This is true for "late" tanks). Early tanks don't have the hole and are much shallower.

Yes the senders work interchangeably. The pax side unit has the added thermistor for low fuel light that won't be used. Alternatively you can swap to a early cluster which the fuel gauge reads 0-60 instead of 0-120 as the early cars only used 1 sender unit. I did this and used the sender unit hole to add venting for rapid fill of the tank.

Yes the long skinny rectangle one.

I have no idea what "sucking air" means other than the car starving for fuel. I've not blown any motors if thats helpful.

I have a custom harness with each pump supplied independently with its own relay, fuse, and wiring. I know guys have gotten away with running them both on the same wire, but technically you would be pushing the limit of the wire and you leave yourself venerable to a cascading failure.

[hoveringuy]

Here's where I stand.

I have a stunt-double fuel tank (it's actually in good shape and hasn't been used to jack-up the car...)

I have an extra fuel pump hangar.

I sourced some 5/16 polymer coated steel brake line at NAPA, as well as the proper inverted flare tee (amazingly cheap!)

I have a good idea of how the pump and lines will sit, but the clearance on the drivers side access is minimal. I think I can grind out the opening a bit to clearance the pump pipe, but the black cover plate will still be sitting on top of it. I will probably also weld a modified cover plate that has an extra inch of clearance. That pipe sits about 1" up and the access cover plate get pretty tight to the tank towards the back.

Do I need to bend the line into the intricate shape of the stock line??

Suggestions welcome...

[hoveringuy]

That hardline if pliable enough to bend closer so it will stay within the confines of the access panel. Now I need to get an additional sender and modify the hanger for a DW200 pump, plus order the hydramat.
)
An important question: is anyone running Hydramat with a turbine (non-positive displacement) pump?

Edit: I did some experimenting and verified that the turbine pump may work...

https://youtube.com/shorts/xjC8JmR1AkY

However, that was with the extra vent hole on the bottom plugged, otherwise it sucked air through that and stopped pumping.

[redneckvtek]

I run the DW Micro pump with no issues.

[hoveringuy]

Here's my final interpretation of the requirement. It's a Walbro GSS430 pump and a Holley 3x8 Hydromat sock. I have the level sender insulated from the body by enlarging the inlet with a die grinder by a few mm and up-sizing the O-ring a bit. The studs have heat shrink over them, plus a fiber washer on the bottom and nylon on top. Resistance between the sender and the tank is 1 megaohm.

I'll very likely have this pump on a separate switch for "track mode".

[redneckvtek]

Can you explain your sender isolation issue? The OEM fitment of that sender on the passenger side requires no heat shrink, fiber or nylon washers?

I only run the passenger side sender and use the early "eta" fuel gauge to compensate.

[ForcedFirebird]

The in-tank swirl pot is a decent rig, but if fuel capacity is an issue like endurance racing, then you are using up precious space. Throughout the years we have had all kinds of variations for starvation and we eventually settled on an external tank (.5l) in the spare tire well that uses an external pump to the engine, and a single stock pump in the tank. The dual pump system works great for heat races, but we found when in a long endurance race, the pumps would seem to burn out prematurely and often. We gathered that the pumps were getting hot when running low on fuel.

The dual pump setup will make your fuel gauge malfunction. The early tanks (and 318) have a single sender, so the fuel gauge needs to be swapped out for one with correct resistance - otherwise the car will read 1/2 when full and empty when empty. The 318 pump hanger already has a return in it (late model 325 return is in the bottom of the tank near the filter).

[hoveringuy]

Can you explain your sender isolation issue? The OEM fitment of that sender on the passenger side requires no heat shrink, fiber or nylon washers?

I only run the passenger side sender and use the early "eta" fuel gauge to compensate.

Using an early gauge and one sender is one solution.

The stock dual-sender solution on the late model tanks is electrically isolated on the driver side because the two senders are connected in series and letting the driver side sender be grounded would short the signal path. The element in the sender is electrically bonded to the metal flange.

I don't know if this a "better" solution or not.