Dual In Tank Fuel Pumps: Post how you are setup
 

Hey Guys,
So I am wanting to install a second intank pump and "Y" them together inside the tank but not sure about how to get the 12v source to them safely..

Can you post how yours is setup and if you have pics please post also..

Thanks,
David

Bump, I wouldn't mind seeing some too.

go in the single turbo area or do a long search. Im running twin walbro's but ran them out of the tank each to a seperate rail, then to the fpr and used the stock feed and return lines as return lines

Crap.. I'm not sure if I took pictures or not, but I simply jumped one pump to the other for power/grnd (which has been argued unsafe, but I've had no issues) and used a 3/8" plastic Y I found at a motorcycle shop (made for fuel) to tie them together in the tank. I ran it right out the stock line.

It's better (for higher HP) to run them parallel (or like teamafx). Use the stock feed and return lines as feed lines. Go straight to the primary and secondary rails from there. After the rails, tie them into the left and right sides of the FPR, and run the return line through what used to be the charcoal canister line. I've never done this, and am not quite sure what happens to the canister though..

rfreeman on nopistons has a huge writeup on his install.. which is VERY nice. It's in the 3rd gen section somewhere I think..

Justin

That's how I've had my fuel run for over 2 years now. No issues. I even jumpered one pump from the other. I think eventually I'll run them parallel but I've had no fuel issues so why bother.

Thanks for the input. Matter of fact.. you helped convince me that it was safe to begin with! :D

?? as in you wired the second pump in parallel with the first one? did you need to beef up the wiring going to the first pump then?? ive heard its already a little thin.

I didn't touch it. I run them at a constant 12v too. There are no signs of overheating or anything like that either.. No discoloration.. not getting brittle.. I can't think of any instances where pump wires failed.. But that doesn't mean it hasn't happened..

I have two. Ran two seperate sets of thicker wiring to the relay. The pumps are T'd together into the stock fuel line for now, but will more than likely run two seperate lines in the future if I stay set up this way. I'll try to dig up pictures of how I attached the pumps to one another.
-Nic

here is my setup:

http://img.photobucket.com/albums/v2...d/DSC04265.jpg

http://img.photobucket.com/albums/v2...d/DSC04267.jpg

http://img.photobucket.com/albums/v2...d/DSC04268.jpg

Just discussed this a few days ago...here are a few images and a link with the discussion; Scroll to the bottom:
https://www.rx7club.com/forum/showth...=395465&page=2

Rob, your pumps look nicely mounted..might have to change mine a bit, but I'd consider running power lines to each pump individually with their own relays/fuses. Otherwise you may power starve the pumps.

That is a beautiful set-up

After the noisy POS SX fuel pump took a shit on me at a major intersection in the summer time and I had to push the car out of the road, I was forced to switch pumps.

My mechanic made a slick looking "Y" design with 2 Nippodenso pumps. Now, my pumps are silent and I should have enough fuel to support more horsepower than my car will ever have with a 13B (I guess I'll just have to go 20B).

Sorry no pictures. My mechanic has pictures, so I'll see if I can get them from him. I'm not sure how they're wired, but I did have upgraded wiring pre-installed for the SX, so it has definitley been upgraded.

Nice! Looks just like mine (minus the fance fittings!)

:)

Ok, Great...this is exactly the kinda responses I was looking for...

In this photo I see some huge power wires going to the pumps...Where are the coming from? and are they "Y"ed together outside the tank and running one power wire to the source? can you explain this wiring? (explain it as if you were telling it to a 5 year old)

https://www.rx7club.com/forum/attach...chmentid=97285

i have to say that this is the setup I saw some time ago that I wanted to duplicate...Now on this setup it seems the power and ground wires were also upgraded but just thickened up inside the tank...Or is it just that I can't see the rest of the wiring?

https://img.photobucket.com/albums/v...d/DSC04267.jpg

I guess I pretty much have the plumbing down..It's just the wiring I am not too keen on...

It seems if you beef up the wiring inside the tank (as in the second photo) you aren't getting the full benefit of thicker wires as if you ran thicker wires straight from the battery...Can you explain the wiring how the wiring is setip on photo 2?

Also, what is that putty looking stuff used to seal the tank in photo 1? Would have to be air tight to keep the pressure in the tank right?

The photo below I am just putting as a comparison...This is my stock pump coming out before I replaced it with the supra pump...As you can see the stock wiring compared to above is quite a bit smaller.

https://www.rx7club.com/attachment.p...id=97722&stc=1

You would have to wear shoes, and upgrade the wires as follows for optimal performance:

Take two wires 12guage or thicker and run them straight from the battery with fuses inline. From there put each wire into a relay (near the tank would be easiest, or next to the fuel pump relay in the engine compartment) and wire them so when the stock fuel pump relay is triggered these will supply the two pumps with current. then run it through the car and drill a hole in top of the fuel pump housing. Install a rubber grommet, run the wires through along with the same size wire for ground. So now you will have two 12gauge wires (positive) and two 12gauge wires (ground) running through the grommet. Seal the top and bottom of the grommet with a silicone or some other gas-proof sealant. Then wire them to the pump. When grounding the wires make sure to sand any paint away and test the grounds with a test light before driving the car.

What size are the fittings to be used?
 

Currently I have only a walbro fuel pump. I would like to add another one. Can you tell me the process of doing the upgrade?

Search it, it has been discussed many times before.

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/y-twin-fuel-pumps-1-feed-line-372570/

Drill a hole in the fuel pump assembly cover and install a 90 degree bulkhead fuel fitting. Earls makes them, or you can use something less expensive from a hydorlcs store. Secure the 2nd pump along side the first with some hose clamps. You're going to have to play around with the positioning of the pumps to get them to fit right, especially the way the sock filters point. At this point you can chose to run a new fuel line for the 2nd pump, use the existing vent line as a 2nd feed, or t the two fuel pump outlets together and use just the stock feed line. The stock feed is pretty small, and I like to keep the vent to prevent fuel vapor smell, so I like to run a new line. The problem with this however, is that it is more work to add another hard line, and running a soft line the length of the car can be dangerous. In your case I would probably just T the two pumps together. Makes it alot simpler. Some people run a pump for each fuel rail, but that becomes a real pain and I don't see much benefit in it. The stock wiring is barely adequate for a single pump, so you need to upgrade it. The stock setup also runs the pump at 9 volts (if I recall correctly) and then steps it up to 12v via relay under load. The best way tp get power in my opinion is if you already have the battery relocated in the bins or trunk. Run a power wire to the pumps. I forgot what guage I used, but it was at least twice as thick as stock. You also need to incorporate a relay into this. Don't use the starter relays alot of people use. They click loudly as they cycle and are not designed for extended use. Gotham usually has the proper ones in stock. Other than that, make sure any hose you use is marked as fuel injection hose and for high pressure. The other cheep stuff will burst over time. Also, solder and heat shrink. everything. I don't trust the crimp connectors for critical applications like fuel.

i have 2 nipondenso pumps that i was planning on using for my project car... but i was thinking it would be nice to mount the two pumps on opposite corners of the tank, so when the fuel starts sloshing around you would (hopefully) prevent starving the motor. anyone done this?

PS for the electrical connections is there special gasoline resistant wire that you need? it seems that there would be but i havent tackled this project yet.

The stock fuel tank is already setup so that you don't have to worry about fuel starvation during hard cornering. That's why there's that metal thingy (for lack of a better word :LOL:) inside the tank.

Thanks for the pics rob20rx7... looks like you T the ground wires close to the second pump, is there a reason why? also, no one use fuel/oil resistant shrink wraps??
Do you think the stock wires will handle the load and not over heat?? Thats one of my concern with your set up. Also, has anyone consider capacitor in between the battery and the pumps?? to reduce initial current drop when pumps turn on due to the high load.

I guess all those years I thought running your car close to empty was dangerous was all a myth.

Well I wouldn't call it a myth. But inside the tank are metal "walls" that trap a certain amount of fuel inside of them so that you don't go lean under hard cornering. Problem is that if you have little fuel in my tank, then that little bit of fuel left inside the walls probably won't do anything.

I wouldn't go that far... Low fuel + hard cornering could possibly cause problems, but under normal fuel levels you should be more than safe.

I just added that because your initial post didn't say anything about low fuel level.

just giving you a hard time.. :)

Thanks Ihor...I am no electrical wizzard so excuse the stupid question...But what part does the relay play in this and why would it be bad to just hard wire the pumps to the battery with a fuse?? I guss they would always be on then :scratch:

This is what I understand from all this. What role does the relay play and where is it wired in?

https://www.rx7club.com/attachment.p...id=97780&stc=1

The relay acts as a 'switch'. Essentially you run the stock wiring to the relay to activate them. Otherwise the pumps would just run and run and run, regardless of whether the ignition is turned on/off. The relay relies on a ignition switch power source meaning it's only hot or on when you turn the ignition key. That's where the stock fuel pump wires come in. They're an ignition switched source. Each relay has four terminals. I'd still run two relays and two sets of wires, one set to each pump.

Ok, so I guess the next question is, what relay should we use for this??

Also, are you suggesting to take the the source of the stock relay and wire them to the relay/s for the two pumps??

Also, why would you want to install 2 relay and not just have 1 relay control both pumps?


Thanks again.

Well they're relatively inexpensive and you'll have two sets of wires, one for each pump. In the end, it'd be more reliable to have two relays instead of splicing everything together. One might overtax a single relay as well. I purchased my relays from RadioShack along with the 25A inline fuse holder. For the relay's power source, I disconnected the stock fuel line wiring leading to the tank and used that. No need to go all the way up to the stock relay.

it was either pettit or peter ferrel (one of the 3 rotor guys) that was having this problem... since they burned fuel so fast this, fuel starvation was a situation they were running into frequently. i dont know how or if they solved it.... but it would suck to have to pull off the track to fill up once you reached 1/3 of a tank of fuel so you didnt blow your motor. i cant imagine that 2/3 of a tank would last them very long at all at those power levels!

The "baffle" inside the tank is what keeps fuel near the pump when hard cornering, braking and acceleration.

I have a 1995 RX7 that was built in December of 1995. Technically it's a 2006. There are a few differences between my car and other 1995 models (and before) such as the ABS system. Another is that I have very little issue with fuel starvation at anything other than an empty tank. I should take a picture of the inside of the tank and will if I have a chance...I have a white plastic "tub" or baffle system which keeps fuel around the pump. Anyone else have this in their car? I heard Mazdaspeed sells an add-in baffle and I'm wondering if that's what is already installed in 96+ 7's.

WOW i had no idea.... id be VERY interested to learn more if anyone has any info...

1996 or 2006?

Wishful thinking on my part I guess...1996.

one thing to consider running two sets of wires to the back, is that if one pump dies on you, the car will still run but when you boost if you have them in parallel, fuel goes to one rail only and you might pop. If you run one set of wires, the pumps die and the car doesn't run at all, saving you an engine. Just another way to look at it.

Both fuel pumps run to a Y so they feed just like the stock pump would and feed both rails sequentially. Wires aren't going to die unless they're overloaded, hence the two sets of thick gauge wire.

i like thid approach better personally. just get one relay that can handle the load (dont know what would be the load from 2 say nipondenso pumps), but it seems safer like that

I plan to use the Y into the stock supply line, teeing both pumps into one. I will let the stock wiring and variable voltage solenoid operate one pump, for normal driving. And use an adjustable boost actuated switch into a relay to switch on the second at about 8psi when the extra fuel is needed. This should keep noise in general and excess fuel consumption when cruising to a minimum...IMO. We will see.

OK so now that we have established how to do the dual pump conversion (relatively simple)... lets talk about some other aspects related to doubling our flow!

what about the fuel filter?? is twice the flow a problem for the stock filter? is it even that great compared to the aftermarket replacements? (and is there any worse place in the world to put the fuel filter... took me 2 hours and tons of swearing to even replace the stock one... thanks mazda... :wink: )

also im wondering if the hardlines, return lines, soft rubber lines, charcoal cannister, or anything else will need to be upgraded if we are doubling the flow of fuel. thats alot of fuel that we are moving around (especially at idle... when its not being used and has to be returned). is there anything about the stock fuel tract that will be a problem??

last thing... we have a fuel pulsation dampener, and a fuel pressure regulator correct? can you guys recomend good aftermarket replacements that you have had good luck w/? i know the FPD is the one that people normally replace (and the stock ones catch fire), but what about the FPR?

thanks guys... this is an informative thread. lets keep it going. -heath

For the FPR, the stock unit is fine even for two Walbro pumps. I don't think it would have trouble supporting 450rwhp. It does 400rwhp just fine. I use an Aeromotive FPR, their new "compact" unit which only features one inlet/outlet as that's all I need. It's a whole lot smaller than the dual inlet unit.

As for the filter and related lines, they're fine to hold the pressure (that's regulated by the FPR and how much boost you're running) but the fuel filter should be changed every 30K minimum as it's essentially the Miata filter and can clog quickly. If you're running lots more fuel through the system, I'd recommend changing it sooner. I'm very surprised no one in the aftermarket industry has come up with a better solution (a kit) to move a larger fuel filter to an easier to service location. Might be down to lack of room.

Form what I understand, people are doing the relocating to the rear rebar just by the tank. I had Gotham relocate mine....Basically it's the filter strapped to the rebar with 2 large hose clamps. I think if you go through the trouble of changing the filter in the stock location you may as well relocate while you are at it.

Double post.....

Thought this new software you couldn't do that :scratch;

what pumps are those in the pics of people with 2?

pat

Those skinny silver ones are the walbro's.

if youve got a digicam lying around, id really love to see some pics of where exactly it is, and how its done. did they end up using an aftermarket fuel filter or the stock one?? thanks, heath

oh, also... is it the Fuel Pulsation Dampener, or the Fuel Pressure Regulator that everyone keeps on going on about is a MUST to replace as they will "catch your car on fire."

PS if one does go w/ an aftermarket FPR, what is the propper pressure to set it at? (sorry its off topic but i was just wondering.)

The fuel pulsation dampner always leaks after time and is in need of attention. As for the fuel pressure, you can search that as I am unsure and it has been talked about before.