Doing some future planning, and I'm looking at (when they become available again) the BNR Stage 2's, and a target of about 400whp. I've combed through some of the search results, looking at the Supra TT, Walbro, the Aeromotive 420, etc. My main concern is, If I go with the Supra TT pump, and if I approach that 400whp number, is it needed to do a fuel pump re wire, or can this pump (or one of the others) be okay as is?

I also noticed on RockAuto the part for the Supra TT denso fuel pump matches the FD fuel pump...is this pump still an upgrade at this point if they are the same part? Did they just adapt the better performing Supra TT pump for use in the FD?

 

Rewiring the fuel pump is always a solid idea. It's basically a free fuel pump upgrade. You don't have to do the whole thing, just feed the circuit opening relay off the battery.

I'm a big fan of the Walbro 255, mine has been awesome for 15 years.

Dale

 

My main input would be to ensure you're getting a genuine pump, from a reputable retailer, regardless of your choice. There are way too many convincing knock-offs running around for budget prices.

 

I'm also interested in what people are currently doing, I guess the big thing mentioned by Dale is doing a rewire. Here's a good thread I found on it with pictures.

I've been looking at the 255 or 350 from Walbro or maybe even the Aeromotive 340 from Banzi (I guess you need to use the universal install kit, but should work).

I'm also curious about which pumps are quiet, not sure how insulated the tank is from the interior. This article shows the 255 being quite loud

Looking at Radium's video from that article almost makes me just want to put the quieter newer F90000 series 400lph pump in.

 

My issue (if you could even call it that, I'd say more of a preference) is I'd prefer to leave the wiring on the car untouched if at all possible. So theoretically if I sourced a denso TT pump from rock auto (even if it shares the same Part number as the FD pump, that makes me wonder if they 'upscaled' the FD pump or 'downscaled' the TT Supra pump) could I push 400whp~ without a rewire? Obviously if it came down to id I'd do the rewire rather than risk damage, but if the stock wiring can be left alone, I'd prefer it.

 

Re wire the fuel pump is consider an upgrade for anybody changing fuel pump for a bigger one.
Walbro 450 work great. Just get the genuine pump and you are good to go as mentioned above.

 

I would upgrade the wiring before the fuel pump, unless you somehow find an aftermarket pump with the same (or lower) current draw compared to the stock one. There are people who have posted photos of melted OEM connectors (near the fuel pump) after switching to the Supra/Denso pump, it seems like it draws just enough current to melt the factory plastic bulkhead connector but not quite enough to pop the fuel pump fuse. I'm having trouble finding the exact forum thread but here are a couple worth reading:
https://www.rx7club.com/3rd-generati...-921896/page2/
https://www.norotors.com/index.php?topic=6346.0


If you haven't seen this thread, it describes a quick and reversible upgrade to the factory fuel pump wiring. That won't help with the bulkhead connector, but it's helpful if you don't plan to replace the wiring between the battery and the fuel pump.
https://www.rx7club.com/3rd-generati...ewire-1124167/
All the work is done in the engine bay, you need about $50 in tools and materials plus some familiarity with wiring (de-pin one connector and insulate it using heat shrink, then crimp two new pins on a new wire and insert that into the housing).

 

Looking over some of the threads, I noticed the one from Regan Rotary Racing saying "The Supra Denso pump flows 290 lph at 43psi at 13.5 volts compared to the FD OEM Denso pump that flows 255lph at 43psi at 13.5v."

I'm somewhat confused by this. If people melt the wires with a supra pump, how/why? Either the information from RRR is wrong, or people are exaggerating (which I don't believe to be the case)

That is what has me confused as to why the supra pump would melt the wires in the pump area if it draws the same voltage, (I'm thinking RRR might be incorrect if that's the case, because that doesn't logically make sense that a pump drawing the same volts would do that.)

I'd prefer to keep the wiring untouched in the car and inside the tank, if it will take a stock legitimate Denso TT pump and not melt anything I'd rather that.

So can anyone conclusively say it will melt the bulkhead connectors with the TT pump at 400whp~? If it will then I'd make sure I have it done, no question.

Also, huge thanks to everyone posting the links for review.

 

The simple answer to your confusion is the wiring in a 25+ year old car isn't like it was when it was new. FD fuel pump wiring when new was perfectly fine for the stock pump, and likely good enough for a Supra Denso pump or a Walbro 255. But as wiring ages, corrosion sets in everywhere and especially at all the connection points. So now each termination adds a little resistance to the circuit, and your fuel pump (whatever model) still needs to consume XXX watts of power to run, and since the voltage available to the pump will be reduced by all that extra resistance from corroded contacts & wire, it will keep drawing more current until a fuse blows. More current = more heat = burnt up connectors & contacts.

FWIW, my FD came with a Walbro 255, and when I upgraded it to a Walbro 450 and did a full rewire, I noticed that the OEM bulkhead connector was pretty badly melted and only suitable for the trash heap.

 

It's simple, you don't yet know enough about electricity to understand the problem that you're trying to solve. Don't worry, it's not too hard to learn. Ohm's law is usually the first lesson, and luckily it's about all you need for this.
V = I*R, or
Volts = Current * Resistance.

If you rearrange to solve for current, you get
I = V/R, or
Current (measured in amps) = Volts (measured in Volts) / Resistance (measured in Ohms).
This is what we care about for now.

First example: your car's turn signals and headlights both receive battery voltage when they turn on, but the headlight bulbs have a lower resistance than the turn signal bulbs so they draw more current through the wires. I'm going to stick to simple estimates like 'lower' and 'higher' so we don't get bogged down by math, since it's Saturday.
Headlight current = (Battery Volts) / (Lower Resistance) = relatively high current.
Turn signal current = (Battery Volts) / (Higher Resistance) = relatively low current.

The two different fuel pumps are acting similar to headlights and turn signal bulbs, the ones with higher flow usually (with very few exceptions) have lower resistance will draw more current through the factory wiring.

Something you might not have considered is that barely-adequate wiring to the fuel pump can often result in lower fuel flow, for instance your 400hp-capable pump might only flow 350hp or 300hp worth of fuel because the factory wiring is not supplying it with at much current as it needs. In that situation, even if the bulkhead connector doesn't melt you're likely to see the engine run lean (not enough fuel pressure) which can be pretty dangerous. Worst case scenario is the wiring works just barely well enough during the first two dyno pulls, then the connector heats up during the third run and the engine runs lean and your engine gets hurt if you didn't have lean protection set up in the ECU. If you're lucky you find the problem and fix it before hurting a second engine.

 

If you are dead set on keeping the factory loom intact, buy the matching bulkhead connector and run separate wiring to the back of the car with a new relay triggered by the factory loom. Not upgrading the wiring is a false economy as you won't maintain voltage under load, when the pump is working against another bar of pressure at high fuel demand. Why potentially burn your car down? You don't magically get more work out without putting more energy in.

Personally if I was doing fuel systems again it would be big supply wiring, individual fuses and relays with a drop in surge tank/pump hanger.

 

Learn from my experience here:

Re-wire the fuel pump. This has been covered in agonizing detail. Search "chuck westbrook fuel pump rewire." There are variations, which I suggest you tailor for your goals. This is as much as reliability mod as it is an upgrade. If you mess with your fuel system, this is to be the first thing you must do.

A 450lph fuel pump make no sense on a fuel system not making 700-ish horsepower. It over-taxes the old Mazda OE wiring and system, and will set you up for a bad day with the amperage draw. Trust me, I learned this the hard way (but it luckily didn't cost me a crispy car).

If you have any doubts, get a shop to do this for you. A reputable shop won't be overly expensive, and you get them to tune your new system after installation.

 

I'd actually call it a lapse in thought. I've taken a few basic engineering courses in college to where I should have thought that through, but it's been long enough that I didn't even stop to consider it more intricately than "if both are x volts why is there an issue" I guess you could say I didn't think, which, I didn't. It's basic simple math, and elementary equations in any electrical engineering class. I have no excuse for not running that through my head in my thought process. I just didn't think.

No sarcasm, I appreciate you typing all that out. That served as a very good refresher.

That should have been common sense/occurred to me that the wiring would increase resistance with age for the reasons you stated above. I've worked on enough older cars where grounding, resistance, etc was an issue, but it's been awhile. This not being able to work on my car where I live for over a year has really taken me out of the problem solving mindset in a way.

I'll look into the rewire, most definitely.

 

there is one where you move the fuel pump power from the ignition switch to something more direct, really easy to do and not only does it give the pump more voltage it also takes load off of the ignition switch. its a lot of win for moving one wire.

 

"A 450lph fuel pump make no sense on a fuel system not making 700-ish horsepower. It over-taxes the old Mazda OE wiring and system, and will set you up for a bad day with the amperage draw. Trust me, I learned this the hard way (but it luckily didn't cost me a crispy car)."
No way in hell a single walbro 450 will give you 700whp on a rotary.
You will need e85 or such and will require more pump than a single walbro 450 to push that much.
https://www.google.com/url?q=https:/...jcVz-xIlOj6iDt

Reed on if you want.

 

Quick plug for @DriftinJim 's fuel pump rewire kit. I am near electrically illiterate and was able to install it pretty easily on my car using the Walbro 255 kit. Very complete and high quality kit that has everything you need and even comes with some nice screws for the pump cover.

https://www.ebay.com/itm/25511944819...d5ee%7Ciid%3A1

https://www.ebay.com/itm/25511944819...d5ee%7Ciid%3A1

 

The grommet that passes through the bulkhead on this kit, is it metal or plastic? I'm asking because I want to get a 100% seal. No leaking fumes, etc.

 

Hey sorry I actually use this kit https://www.ebay.com/itm/255119435906?

It is a 255 kit do you do not use a separate grommet. I will be ordering the kit I posted earlier for a 450, when I upgrade.

 

Is it ok to do both re-wires? I completed the under the hood fuse box re-wire "888 Werkes" mentioned above about 2 years ago. I am now in the process of upgrading my fuel pump and re-wiring it through a relay now. Do I need to undo the under the hood re-wire?

Thanks

 

Are you talking about at the fues box? If so, i did the same and did re wired my pump and works fine so far.

 

I had a little time so I wrote down some thoughts about this. This is a very underrated yet beneficial step. On my 350 whp twins car I retained the fuel pump relay to keep the voltage step down. As I started adding mods to the car ( read - m2 air box, downpipe, high flow cat, cat back ect ) I wanted to make sure I could retain the factory wiring and step down relay to extend pump life yet still get enough flow for the Supra pump to safely cover the needed lph. I am running the 550cc primaries with Rc 1300 bored secondaries. I found a write up that covered removing the fuel pump feed that went through the ignition switch as you described. I took before and after voltage readings with my fluke and noticed a .5 volt increase at idle ( I actually had to readjust the idle area fuel some ). The fuel pump wiring originally went through the ignition switch as a safety feature. I’m not suggesting removing that, merely describing what I did. Having said that, I believe that 95% of people should never touch the wiring on their car. I have seen more hack jobs and **** poor excuses for wiring than I can remember. On my other car, the single Turbo with fuel requirements much higher, I run a walbro 450 rewired for Constant voltage. One thing people seem to overlook when rewiring their fuel pumps is the more recycled fuel that returns to the tank unused is heated up by the engine as it passes through. I’ve noticed a definite increased in fuel temperatures after a duration of time from re-wiring and running a constant speed. This becomes worse as the fuel level drops recycling hot fuel the entire time. Though I don’t disagree The fuel pump rewire has its merits, I don’t necessarily agree it’s right for everyone. I found on more moderate builds having just moved that one wire and dropping in a pump to be adequate. Having consistent pump voltage is paramount. A solid charging system, alternator and battery goes a long way in creating that.

There is also a modified version of the ignition bypass as well. The wire bypasses the ignition switch and the feed is changed to a larger size and moved from the fuse block over directly to the battery with a inline fuse. The load wire has a new piece of wiring ran back from the relay to the pump in a larger size to keep voltage drop down. This retains the two speed pump but uses new wiring. Again, I don’t suggest 95% of people should touch the wiring on their car.

Just a note on pump choice from my experiences. The walbro 255 which I believe is the drop in version seems to work as well as the supra pump. Far cheaper and flows more than the stock pump with zero mods. The supra pump again drop in and flows more than stock. The only time I’ve seen a Supra pump flow higher rates than the equivalent walbro ( i’m forgetting the exact number pump it’s either the 255 or 350 ) is at higher voltages. The negative to the supra pump is cost and finding a authentic one. I would avoid the 340 stealth pump like the plague. They have a notorious problem for becoming weak after a long duration run times and high fuel temperature saturation. It took me a while to find that issue with them.

Don’t get in the pitfall of overdoing every aspect. You’ll start to get in the domino effect. That’s how these cars spend more time on jack stands then out being enjoyed.


~ GW

 

I’m way out of my depth with wiring but fwiw, when I replaced my pump I seem to remember a chassis ground with a 10mm bolt that’s worth a look and cleaning if you’re back there.

 

i have an FC, so i'm jealous, moving the one wire would be a huge job for me... that being said i was able to get within 0.5v of battery voltage at the pump with the stock wiring and parts. i needed to rebuild the ignition switch,
it would be nice to take some load off the ignition switch, but i'm getting good voltage at the pump so no real need to do anything more.

 

Ah, the fc is alien to me. Sounds like you got it figured out tho.


~ GW

 

Would I be correct in assuming a denso supra TT pump from rockauto would be a safe bet for being authentic?

The only thing that confuses me, is the pump on rockauto for the TT supra, (the denso one obviously) has the same part number as the FD pump. So did they downgrade the Supra Pump or upgrade the FD one? Or is that just a parts catalogue error?