Fuel tank mod

[redneckvtek]

I run the DW Micro pump with no issues.

[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.

[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...

[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]

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?

[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.

[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.

[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.

[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?

[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]

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

[Erik]

Such great information! Legend!

[redneckvtek]

Thanks, REALLY helpful!

If I understand this correctly, the thought process for running 2 of the high pressure pumps (in addition to being cheaper/simpler) is that when one starves for fuel, the other delivers fuel and slams shut the check valve on the starving pump?

So all you need is for one pump to have fuel? And by the sound of it, running both does not wear them out faster?

I’ve already got the low and high pressure pumps, but am thinking I go this route. THX!

The driver side pump isn't needed at all until the car has been on track for about 90 minutes (assuming stock or mild power modded M20, M50, or M54).
After that, the fuel bowl on the passenger side (in conjunction with the venturi powered crossover, called the "sucking jet pump" in more modern terms) is not sufficient to keep fuel at the passenger side pump.

What we do is turn the driver side pump on about half way through a fuel run.
Running both the whole time hurts nothing. this happens occasionally when the driver forgets to turn the 2nd pump back off after a pit stop.

With two "high pressure pumps" already in the car, failure of either pump results in a shorter fuel window (about 90 minutes).
With one lift pump and one high pressure pump, failure of the lift pump is a shorter window (again, 90 minutes). Failure of the HP pump is a ride on the roll back.

[Leebo]

Thanks, REALLY helpful!

If I understand this correctly, the thought process for running 2 of the high pressure pumps (in addition to being cheaper/simpler) is that when one starves for fuel, the other delivers fuel and slams shut the check valve on the starving pump?

So all you need is for one pump to have fuel? And by the sound of it, running both does not wear them out faster?

I’ve already got the low and high pressure pumps, but am thinking I go this route. THX!

[redneckvtek]

The low pressure to high pressure solution works, but its complicated and costly - IE sourcing a 318is pump for the two inlets or using the 325E 55l tank pump and 14 adapters to get the sizes back right.

Its (in my opinion, anyway), much simpler and more robust to just install two high pressure pumps.

Just buy another 88L high pressure pump (just like the one that goes on the passenger side). Put that in the hole on the driver side.

buy a 5/16" tee. Cut the fuel line near the passenger side pump. insert tee. Clamp it up.


The fuel pumps all have a factory installed anti-drainback valve in the outlet of the pump itself. Not on the metal hanger, but actually IN the pump.

The little plastic white connector between the pump and the hanger is a failure point also. I've had two give me issues. Standard procedure is to replace with submersible fuel line at this point. Gates 27093. Yes, its $20/foot. Thats enough for 2-3 cars with 2 pumps per car.


I've won a few enduro's with E30's with this setup.
For extra fuel range, there is a Holley Hydramat which will attach to the OE pumps and fit into the stock tank.



Leebo to directly answer your questions though.

To wire the 2nd pump, its better to go back to the engine bay. Then you wont be putting twice the expected amps through the stock wire. There is a nice Aux fuse box on the side of the normal fuse box with two populated slots (and 2 empty ones). One of the populated ones is "key on" and one is "always on". That should get you what you need.


The 3 wires include the wire for the "low fuel level: light.



On the driver side one you are adding, you will attach the two car wires (both BR/GN) to the pigtail Br/GN and BR wires. The BR/GY wont be used.