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I'm working on the layout of the boot of my build. I've got my fuel tank (thank you Jack @ Kinetic Vehicles) and it's going to be placed roughly in the position shown in the photo below.


In the back of my brain, I seem to recall that external fuel pumps should be mounted below the level of the bottom of the fuel tank. I don't know that it's true. I'm really asking.

It would be a huge packaging advantage if I could place the fuel pump and filters in a special "tray" as outlined in red in the photo. Will that work with an external fuel pump? Does it require a special kind of pump? Is it inadvisable?

The tray would be about level with the top of the tank +/- 1" or so.

Thanks,

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Damn! That front slip angle is way too large and the Ackerman is just a muddle.

Build Log: viewtopic.php?f=35&t=5886

Many (most?) of the newer quiet running fuel pumps do not "Prime" very well so need to be mounted low.
Not all, you will need to get one that does self prime well if you mount it high.

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If I must be a one-man PC free zone, so be it!

There are better, more complicated methods for an external pump and top tank fittings but that will work.

If the fittings are going to be through the top of the tank, a high mounted pump is better for a shorter length of tubing to prime. There is an internal check valve but they are know to leak and lose the prime over time.

A low restriction in-tank sock pickup is better than an external filter between the pump inlet and tank.

_________________
Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS cheap viewtopic.php?f=5&t=13225&p=134742
Simple Spring select viewtopic.php?f=5&t=11815
Frame LxcockpitWxengbayH
Lotus 7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12

@RichardSIA
Thank you, Richard. It looks like good self-priming is now a criteria for the pump. Thank you.

@MV8
The setup on the tank is fixed as you see it now. There's foam in the tank and the pickup (red cap in foreground) is already installed to the bottom of the tank. The dark blue cap next to it is the return line from the fuel injection system. The far dark blue cap is the vent, black is the sender and big red is the filler (sorry, pretty obvious).

I'm completely open on the actual components and arrangements. I'm looking for those items now. Generally, I go for simplicity and reliability. Like I said, having them up top would be a packaging (and maintenance) advantage, but nothing has been decided yet.

So, if you have some ideas feel free to toss them out there.

Cheers,

_________________
Damn! That front slip angle is way too large and the Ackerman is just a muddle.

Build Log: viewtopic.php?f=35&t=5886

For an external inline efi pump, I'd use the walbro gsl393:
https://walbrofuelpumps.com/walbro-gsl- ... fuel-pumps

I'm sure carter has a similar pump but I didn't look it up. I prefer carter gerotors for returnless carbs systems. Some oems have great pump systems but I assume you want new and don't want to pay $500 or more for a pump.

The vent should go to a tank vent tank like the early rx7 type that Chuck has. I like the jeep type (easier to find). Using coiled loops of hose is not a good replacement for a breather tank but it works to a degree.

A cheap, carb type inline pump could pull from the tank to fill a small tank with either a typical oem type internal pump or directly feeding an inline pump. The return line dumps into the small tank, helping to keep it full. Excess fuel is returned off the top of the small tank to the main tank. This system would be oem quiet, can be located in a convenient location, and doesn't need foam or baffles in the main tank to ensure the pump is not damaged or the pressure doesn't drop from picking up air. The cheap pump could be controlled separately to prime the small tank.

_________________
Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS cheap viewtopic.php?f=5&t=13225&p=134742
Simple Spring select viewtopic.php?f=5&t=11815
Frame LxcockpitWxengbayH
Lotus 7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12

@MV8
Excellent. Places to start. I was wondering what is done with the breather.

Thanks,

_________________
Damn! That front slip angle is way too large and the Ackerman is just a muddle.

Build Log: viewtopic.php?f=35&t=5886

I used the pump mv8 just recommended to you. I am running a different setup now, but it was actually installed by the front firewall and had no trouble pulling fuel.

https://www.amazon.com/Walbro-GSL392-40 ... 150&sr=8-3

@gto7419

Thank you for that information.

Cheers,

_________________
Damn! That front slip angle is way too large and the Ackerman is just a muddle.

Build Log: viewtopic.php?f=35&t=5886

I am using Bosch 69100 fuel pump but I placed mine directly below the fuel tank for gravity feed. I found this fuel pump when researching my build and finding it popular amongst the offroading crowd when they swap in V8s into their jeeps. It is a Bosch version of the E2000 fuel pump Ford used on V8 F150s. No need for primer pump. I can show you my fuel pump set up if you like. It is easy to get to. I just installed the Bosch fuel pump as I originally had a super cheap E2000 from Amazon that was getting very noisy after running very low on fuel once and I didn't trust if for a upcoming track day. It only took me about 10 min to swap out the fuel pump from the point that I pulled the car in the garage to the point that I turned the key and started it back up.

https://www.amazon.com/Bosch-69100-Original-Equipment-Replacement/dp/B000BZIC90

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Build on

Chris
Build: NA Miata based +221 Se7en

I agree, those are good pump applications for bosch or carter replacement pumps and should hold up similarly to the conservatively rated output walbro pump, but the ford applications for your pump also have an in-tank pump and a mini-tank like I described above.

If you don't need it to last as long as an oem pump, it can last for a while depending on the installation details and actual use. A new pump should have a little excess capacity (some return flow at WOT and high rpm). Picking up a little air briefly will damage the pump with no indication that it happened. Return systems tolerate diminishing pump output without normal drive ability issues. Eventually, the pump cannot meet the engine requirements either from high mileage/normal wear or sooner from picking up air.

_________________
Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS cheap viewtopic.php?f=5&t=13225&p=134742
Simple Spring select viewtopic.php?f=5&t=11815
Frame LxcockpitWxengbayH
Lotus 7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12

There appears to be room on the left side of the tank (facing forward). Can the pump go there, down low? The pic appears to show the tank as extending only part way down (hard to tell for sure though). If so, why can't it go below the tank and be easily accessible from below? On a somewhat related note, having it located down low likely helps to keep it out of "the line of fire" from getting hit by a trailing car's bumper.

_________________
Midlana book: Build this mid-engine Locost!, http://midlana.com/stuff/book/
Kimini book: Designing mid-engine cars using FWD drivetrains, http://www.kimini.com/book_info/

@FieroReinke
Thank you, Chris. You're the second person to reccomend that pump. One advantage I see with the Walbro setup is the flexibility of the fittings availabe at either end of their products. I'm really planning a system of pieces tied together: filters, pump, lines from tank, etc. It's a little easier to do with their products because of that flexibility.

@KB58
The original concern, Kurt, was keeping that space below the tank open for routing the exhaust. It looks like I'll be able to run it under the chassis now, so that's gone. However, I really like the idea of having it up high and easly accessible. The fuel lines have alway been intended to run along the top of the transmission tunnel. The location up high is ideal for that route.

Also, it leaves me some room down below for storage space. I'm keeping the Mustang jack and that would be a good place to stow it.

Cheers,

_________________
Damn! That front slip angle is way too large and the Ackerman is just a muddle.

Build Log: viewtopic.php?f=35&t=5886

An old discussion about the ford system:
viewtopic.php?f=27&t=18006&p=213887

_________________
Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS cheap viewtopic.php?f=5&t=13225&p=134742
Simple Spring select viewtopic.php?f=5&t=11815
Frame LxcockpitWxengbayH
Lotus 7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12

For what it's worth, you can install a new tank fitting at the bottom that will seal to that tank - that's what I did. I removed the anti-slosh foam, drilled the hole and installed the fitting, then reinstalled the foam. Unbolting the top hatch allowed me plenty of room to get my arm in there to do all that. I also tried to install it as near to the middle of the tank as my setup would allow, so as to reduce the impact of fuel sloshing on hard corners.

Here's the fitting I used, which includes an in-tank pickup screen. https://www.summitracing.com/parts/MRF-MP-7026BLK


Could you possibly manage something similar, maybe coming out the back?

@ZiG

Thanks for that information. I'm going to use what I have. It looks like I can get the pump lower than initially thought, and I think it's going to be OK. If not, I'll have a couple of options like a check valve to keep fuel in the hose to the pump or replacing the Walbro pump with one better at self-priming.

Thanks again,

_________________
Damn! That front slip angle is way too large and the Ackerman is just a muddle.

Build Log: viewtopic.php?f=35&t=5886