EFI Fuel Cell Install

[CBoynton]

Recently picked up a early 76 280z as a long term project. Both the spare wheel well and the gas tank are trash from rust. I am slowly working through all of the other issues (seized brakes, body rust, etc). The previous owner installed dual webers but I want to reinstall the EFI. One big change I was planning before I realized the tank was shot is to install a 15 or 20 gallon fuel cell. I have a few questions to go along with this. To preface, I plan to run new AN fittings and braided hoses since I can't trust the old steel lines. I will be using the stock EFI, but will install the Megasquirt system in the future.

1. What is the flow rate and PSI for the stock fuel pump needed to run the EFI?

2. Would it be better to use a baffled EFI fuel cell with an in tank pump (ie Holley), then bypass the external pump? Or just use an external pump and a fuel cell with foam/wiffle balls?

 

Thank you! I have read a lot of threads on here already, this forum is such a huge help.

[NewZed]

The Airtex E8312 is a common aftermarket pump for the stock EFI system.  It will put out 90 psi (unnecessary, too much) and about 30 gph (also more than needed).  

 

Don't get carried away on a bigger popular pump like the Walbro 255.  255 lph is 67 gph.  Way too much flow and the pump will make a lot of noise trying to push through the small L28 fuel lines.  There are several online calculators out there.  https://www.google.com/search?q=horepower+fuel+pump+calculator

 

You haven't described what you plan to do with the car.  The race guys often use a swirl pot or surge tank.

Edited December 1, 2023 by NewZed
8212E > E8312

[CBoynton]

10 hours ago, NewZed said:

You haven't described what you plan to do with the car.  The race guys often use a swirl pot or surge tank.

The goal is to just street it. Upgraded brakes, suspension, sound insulation, full upholstery overhaul. Make it a touring car with enough power for fun but the comfort for a long trip if we want to.

 

The fuel cell is mostly because the rear is shot and I have to store the gas somewhere. It'll be cheaper to do a fuel cell and seal up the spare tire area than to replace the tank and metal.

[AydinZ71]

My preference is external pump, in every case. Key is to mount the pump either at or slightly below the elevation of your tank/cell. If EFI and NA, a single high-pressure pump in the rear of the car with a regulator at the return end of your fuel rail, is fine. Use the OEM fuel line as a return, and run a new 3/8” hard line from near your pump to near your fuel rail at your firewall. If you want AN fittings throughout, you will need to run a new hard line for the return as well, since OEM is hose barb. 1/4” or 5/16” is fine for a return line. 

for high power application (turbo, SC), I prefer a low pressure high volume pump in the rear, a surge tank in the engine bay, and a high pressure pump mounted below the surge tank. Regulator return drains into the fuel surge tank, and surge tank overflows back through your tank return line. 

I think fuel cell is just a flex and overkill for a street car. I just modified my OEM tank to accept a new fitting for a fuel draw line. Up to you. If you are worried about fuel slosh, just install a 1qt surge tank in your engine bay and follow the directions I provided for a high HP application. It’s not sloshing all the time, and the surge tank will solve starvation issues. Much cheaper than a fuel cell for a street car. 

Edited December 2, 2023 by AydinZ71

[NewZed]

12 hours ago, AydinZ71 said:

I think fuel cell is just a flex and overkill for a street car.

Unnecessary opinion.    Aren't you "flexing" with your performance knowledge? 

 

You can find threads out there about modifying tanks from other brands of car.  You can also get replacement tanks, but they're expensive.  It's one of those do-the-math situations.  Good luck.

 

https://s30.world/product/01-75-till-12-76-datsun-280z-fairlady-z-fuel-tank-vapor

[AydinZ71]

@NewZed *shrug* it’s a lot of money and a ton of fabrication work to net you a tank. I suppose I gave the impression showing-off was a bad thing? OP, do what makes you happy. All my opinions are generally unnecessary ☺️😂

[CBoynton]

6 hours ago, NewZed said:

You can find threads out there about modifying tanks from other brands of car.  You can also get replacement tanks, but they're expensive.  It's one of those do-the-math situations.  Good luck.

 

https://s30.world/product/01-75-till-12-76-datsun-280z-fairlady-z-fuel-tank-vapor

I have looked into this before and it was on one of my budget plans. But in the long run, it would actually be cheaper to buy a fuel cell and run new hoses/fittings than to fix all the rust issues and buy a new tank.

[Ben280]

Going to agree with @AydinZ71 on this one and recommend you get a new factory style tank and external pump. A fuel cell used to be the "easy" route, but if you want one with proper baffling, pumps, surge tanks etc, you are looking at double the cost of a factory style tank, and that doesn't include the fab work to make it fit. Fuel cell's also require semi frequent inspection which is unnecessary on a OEM style tank. 

 

If you DO want to use a fuel cell, the Radium FCST setups are the way to go, and is what I have in my car. I have 2 AEM 50-1200 pumps in there. They were great with the old L series motor and are doing just fine with the LS. When you do the AN lines, be sure to get ones that are rated for ethanol. A lot of the rubber in the standard lines isn't designed for any amount of ethanol, so the E-10 in typical pump gas will make them rot out. 

[calZ]

There's also this option, which is meant for EFI conversions. It allows you to use a retrofit in-tank pump, or an OEM pump if you're going LS swap or similar. 

https://www.vintagetanksolutions.com/products

[jhm]

FWIW, I agree with @AydinZ71 as well.....on just about everything he said.

 

@CBoynton, if you've decided that fuel cell is the best solution for your particular situation; just make sure it's installed correctly and SAFELY.  I've seen way too many installs done incorrectly.  As an alternative to the cell, have you considered "sealing off the spare tire area" (your words) and replacing your current tank with a used OEM tank?  They're still available for $200-300 used.  Just throwing out ideas here....

[NewZed]

On 12/1/2023 at 10:15 PM, AydinZ71 said:

I think fuel cell is just a flex and overkill for a street car.

 

10 hours ago, Ben280 said:

Going to agree with @AydinZ71 on this one

 

10 hours ago, Ben280 said:

If you DO want to use a fuel cell, the Radium FCST setups are the way to go, and is what I have in my car.

 

Are you racing or flexing?   Ha ha....

[NewZed]

One fact that has been verified by many but might not be well-known is that the factory stock 280Z tank and fuel system suffers from fuel starvation on long left hand turns if the fuel level gets below about 1/3 full.  You can find commentary about it in the various surge tank threads, I've had it happen to me a few times.  It's a design flaw.  It's pretty startling to have the engine cut out if you're accelerating through a wide long left on a busy street, on low fuel level.

 

Something to consider for anyone rebuilding their fuel system or just looking to correct a real flaw in the system.  A valid reason for a street car mod.

[AydinZ71]

@NewZed if one were to avoid using a surge tank in the engine bay, I agree. You would have to solve your slosh/starvation issues at the tank. Even a momentary vapor bubble pulled into your fuel line will cause a problem with EFI, if the ~40psi doesn’t cause it to collapse. SU’s, you would be OK to a point, since the fuel dumps into an atmospheric reservoir anyways (float chamber). I am a big fan of the quart surge tank though. S30 has a ton of space up front to choose from, but it would be a struggle to fit Z31+. That’s a heck of a lot of fuel to run-through, and the shape means you will use it all before you pull Vapor into your EFI pump. To be specific, this is my experience with the L28et street Z I have (@16psi). 
 

Have not raced yet… I’m just an Engineer that comes-off as a know-it-all, and humbly accept criticism as a result. I don’t mean to be condescending, but I recognize i can be. 
 

John and Ben are real racers though  

 

cars almost running! Should be hitting the track by Feb (thanks to my California mortgage payment). 

good luck to the OP! 
 

PS: same problem to consider with oil starvation, but it would take significantly more lateral G’s than what it takes to suck Vapor in your tank when <1/3 tank. 

Edited December 3, 2023 by AydinZ71

[jhm]

4 hours ago, NewZed said:

One fact that has been verified by many but might not be well-known is that the factory stock 280Z tank and fuel system suffers from fuel starvation on long left hand turns if the fuel level gets below about 1/3 full. 

You are 100% correct there, @NewZed.  I have actually had starvation issues with tank half-full (or more).  Solution that worked for me was a surge tank and a better pump at the rear....now I can run the tank almost to empty, even during hard track use with sticky slicks. 

 

Hopefully this discussion has helped the OP.