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Carburated fuel tank to EFI tank


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#1 Jelmer C31

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Posted 09 December 2016 - 01:03 AM

I'm in the middle of installing a JDM VG30DET in my C31 Laurel. It was carburated and has 2 6mm fuel lines from tank to engine. I'm going to replaced them with 8mm steel lines but I'm still in doubt about the connections on the tank it self. It has the 2 6mm lines on the front/side of the tank which are welded/soldered on. I could modify the sending unit and put my Walbro pump in there but space it tight there. I also have an external Bosch pump that I could use.

 

What have you guys done with similar fuel tanks?


1984 Nissan Patrol 160 L28E --->L28ET in progress

1983 Datsun Laurel C31 L24 --->VG30DET in progress


#2 datsunrides

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Posted 09 December 2016 - 07:01 AM

Take a look at the tanks inc in tank fuel pump kit. I installed one in a 1200 tank, which is fairly shallow. The problem with an external pump without either a sump or surge tank setup with EFI will be fuel starvation when cornering once the fuel level gets to around 1/4 tank or so.

#3 Lockleaf

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Posted 09 December 2016 - 09:54 AM

Perhaps more work than you are interested in doing, but here is how this guy converted his stock 76 Mazda fuel tank over to FI.


Half Pint ('71 510 Goon) http://community.rat...agon/p?=1269361

 

Audrey ('69 Roadster 1600) http://community.rat...rey-the-ratster

 

Tiny Havok ('85 720 DIY built Crewcab 4x4) http://community.rat...ache/?p=1395455

 

720 Shenanigans http://community.rat...20-shenanigans/


#4 G-Duax

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Posted 09 December 2016 - 01:37 PM

I have never run into problems with an external pump for EFI, if everything is plumbed up correctly.

Common conversion in Japan also.

They are big on the Bosch 044 pump, mounted externally.

You just have to run a larger pick-up tune from the tank, going to the pump.

And while your at it, mount a fuel filter sock, hung from a length of hose, so it's sits on the bottom of the tank.

I've found pick-up socks made to hang from -6 & -8 hoses on eBay.



#5 CGraves

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Posted 10 December 2016 - 11:37 AM

I'm in the middle of a RB25 swap on my 260z and basically how my setup works is.

Stock tank>Low pressure pump>Surge Tank>Walbro 255 HP pump>Nismo FPR>Engine.

 

I didn't want to get a new tank so I ended up going for a surge tank with 2 inline pumps. Cost for my whole setup was like $400.



#6 Jelmer C31

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Posted 10 December 2016 - 02:01 PM

How do you deal with the small diameter outlet on the stock tank?

1984 Nissan Patrol 160 L28E --->L28ET in progress

1983 Datsun Laurel C31 L24 --->VG30DET in progress


#7 CGraves

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Posted 10 December 2016 - 10:38 PM

The 240z/260z tanks are 8mm from the factory or 12mm on the EFI 280z's. 

 

I don't see why a 6mm outlet wouldn't work to be honest though.

 

If you end up going with an external pump make sure you get a surge tank.



#8 Jelmer C31

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Posted 11 December 2016 - 06:43 AM

6mm is to small if you plan on 300+ Hp

1984 Nissan Patrol 160 L28E --->L28ET in progress

1983 Datsun Laurel C31 L24 --->VG30DET in progress


#9 G-Duax

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Posted 11 December 2016 - 08:52 AM

Cut the 6mm line off, flush with the tank, and weld it shut.

The install a bulkhead fitting somewhere close to the fuel level sender, that you can still get your fingers to.

Install a drop hose with a filter sock on it, onto one end of the bulkhead fitting, drop it in though the fuel sender hole, and then up through the new hole.

Screw the retaining nut on to the fitting, and you are done.

 

Here is the one I used, just used an old AN fitting machined to match the end of the 18mm fitting.

http://www.ebay.com/...MFUfT4F&vxp=mtr

 

Or this one for a little more if you don't have someway to machine an old AN fitting to match what the filter sock needs:

http://www.ebay.com/...CpYBRz-&vxp=mtr

 

You probably want to do the same to the return line, since at idle you are returning almost the full volume of fuel being put out by your pump.

You of course don't need the filter on the return line, but you should still run a drop line so that you are not aerating the fuel by it spraying into from above the fuel level.



#10 Stoffregen Motorsports

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Posted 15 December 2016 - 04:52 PM

Yes, http://www.tanksinc.com/makes a great drop in unit for any tank. With a fuel pump, the kit costs about $225.

 

Tanks Inc pump in '85 Land Cruiser

 

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If you have access to the tank from the car that the engine came out of, I would just use that setup and weld a boss into the top of your tank. I've done it multiple times.

 

Toyota Tacoma pump in my '83 Toyota pickup

 

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Toyota pump in my Land Rover

 

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