Walbro 450 or 480 or 525 or Hellcat fuel pump in IS300 stock hanger - also Solid State Relay fuel pump control

Hodgdon Extreme · Apr 14, 2022

This post covers how to install a big Walbro 450/470/480/525/535/Hellcat (they're all the same, externally) fuel pump into the stock hanger assembly in the IS300.

Later, it covers how to implement a solid state relay for controlling fuel pump speed - so you don't simply need to have that big pump just "on" or "off".

Background:
My turbo car made 470whp on 40% ethanol with an old walbro 255 high pressure pump, but I was losing fuel pressure. I am upfitting my ecu, adding full flex fuel capability and want to use E85 fuel which requires more fuel than E40 - and I want to turn up the boost a little and comfortably crack the 500whp mark. Turbo is probably good for 550-600, but I think I'll be happy in the 525-550 zone.

I have no need for a dual pump arrangement, don't want the heat associated with dual pumps, and don't want the complexity of staging pumps based on boost. My ECU is already about maxed out on digital outputs, and I don't want to rely on a $12 chinese hobbs switch to ensure I don't lean out under high load. Also, it doesn't seem very elegant to have a fancy, all-integrated ecu - but then control the secondary fuel pump with a ghetto external circuit.

So I decided to try to fit one of the big new Walbro pumps into the stock hanger - so I could avoid buying a new hanger, and avoid fabricating one from scratch.

Frankly, I'm too lazy to give you a step by step tutorial on this - and honestly it wasn't that hard. But I did take a bunch of pics so you can see exactly what I did to make it work. I'll add some notes to help you get the idea of what you're looking at.

How I did it:
First, the completed assembly minus the fuel filter sock on the pump inlet.

The fuel return line is the steel 90º 5AN fitting. That was installed by the dude that originally setup my car way back in the day.

I added a Deatchworks 90º 6AN bulkhead fitting for the supply line.

I added a SealCon 3/8NPT cable gland to run 12AWG wiring to the pump. The original pump relay and wiring is NOT up to the task of supplying the 20-23 amps the Walbro 450s draw. This cable gland is made of fiberglass reinforced nylon, has a neoprene insert for the cord grip, and a buna-n oring to seal the flange down to the lid of the hanger. All these materials are fully compatible with both gasoline and ethanol.

I had to do some grinding on the body of the hanger assembly to get it all to fit.

The pump outlet of the OEM pump is a nipple that gets forced up against the hanger so the pump discharges into the fuel filter housing that surrounds the pump itself. Then the filter housing has a fitting for the OEM fuel line to connect to. I eliminated this because the big Walbro has a 3/8" hose barb outlet.

With the hanger lid snapped onto the hanger body, I drilled straight through the pump discharge hole - and through the lid. Now I have a hole in-line with the pump discharge.

Then I ground away the hanger body so the pump would fit.

I shortened the "pump support tube" plastic that surrounds the pump about 25mm so the bottom of the new pump will be in the same place as the bottom of the original pump. I ground two slits into the suppor tube so I could pinch the support tube down onto the pump with a hose clamp to support it.

I clipped off the 14awg leads as close as practical to the pump so I could use as much 12awg as possible. I used open barrel splices. Note I staggered the splices so if the heatshrink tube fails - the positive and negative leads still won't short together.

There is not much room to work with, so I shorted my 6AN pushlock hose-end by one full barb. I used a cheapie "evil energy" hose end from amazon; they have two barb ridges - I cut one off.

I also cut one barb ridge off the pump outlet. If I hadn't done this, the pump discharge and 6AN hose-end would have butted against each other, and the pump would have sat too low in the hanger.

I should also mention I had to make a 1/4" thick spacer to put under the Deatchworks 90* bulkhead fitting to space it up enough to make room to make this whole thing work. You can see that in one of the pics above.

I used a small piece of Gates submersible e85 compatible fuel line to connect the pump to the hanger lid.

The length of the hose has to be JUST RIGHT, so the 6AN hose-end tightens up just as the fat bottom of the pump is getting pulled up against the pump support tube.

I used Oetiker clamps because they're super reliable.

The hanger lid needed two new holes - one for the new fuel supply fitting, and one for the cable gland for the 12awg wiring. The hole for the supply fitting must be in-line with the pump discharge. There isn't a whole lot of real estate left for the cable gland, so you'll pretty much have to put it in about the same place I did. In fact, I goofed and placed my cable gland hole too close to the sidewall of the hanger lid, so I had to grind the hex off the locknut to make room to spin it. I didn't mind this because the cable gland is has 3/8NPT pipe threads plus an o-ring seal on the underside of the top flange...the nut is really only a safety. I'm sure it'd be fine without the nut altogether.

The tube nut on the 6AN hose-end has to be tightened as the whole thing gets snapped together and assembled, so I ground a window into the side of the hanger lid so I could fit a wrench in there to tighten the fitting. (I used a die grinder and a carbide burr for the grinding. I wish cylinder heads and manifolds ported this easily)

The OEM arrangement has a grounding point and an earthing point spliced into the negative lead to the fuel pump. I clipped the lead off the splice that originally went to the fuel pump, and then clipped the positive lead off the fuel pump connector. I plugged the connector back in, the grounding and earthing points will still be connected to their original points in the car. I'll add a new grounding lead from the negative terminal of my new heavy duty fuel pump relay - running to a ring terminal under one of the screws holding the hanger assembly to the fuel tank itself.

It's really not a hard job at all. It does eliminate the original fuel filter so it's a (really) good idea to add an inline fuel filter.
I can't stress enough that OEM fuel pump relay and wiring cannot handle the current draw of these big Walbro pumps, so you need to re-envision your wiring arrangement.
I bought a made in USA Omron 50 amp relay. I'll trigger it with the hot lead that previously powered the original fuel pump. My battery has been relocated to the trunk, so I'll add a 30amp breaker off the main battery disconnect - and run 10awg to the relay which will be located under the back seat, near the fuel pump access panel.

Alternatively, and certainly more elegant - would be to use a spare output on your fancy ecu to drive a Solid State Relay (SSR). This way, you can calibrate a table or map in your ecu to command a pump duty cycle that is adequate to maintain whatever fuel pressure you need. This way you can basically have a big pump just "idling" when you're simply cruising around, and only drive the pump hard when you are into boost. Depending on your ecu, this can be as simple or complicated as you desire. The OEM's do it this way. In fact, they have such exacting control of the pump they don't even need a fuel pressure regulator.

Hope this helps someone in the future.

Hodgdon Extreme · Apr 14, 2022

Link to testing of fuel pumps: In-Tank Fuel Pump Comparison Test - Real Street Performance

The SealCon cable gland part numbers (much cheaper than summit):
Cable Gland body: CD09N2-BK
Locknut: NN-09-BK
Oring: OR-38-BN(G)

Deatchworks 90º 6AN bulkhead fitting: DWK-6-02-0710

Earls rubberized stat-o-seal sealing washer to seal bulkhead fitting to hanger lid: EAR-178109ERL

Gates 3/8" submersible e85 compatible fuel hose: 27097

Omron relay: G8JN-1C6T-F-R-DC12

Walbro 450 LPH "high pressure": TIA450-2 F90000274

This is the same pump as the xxxxxx267 part number, with a higher relief pressure. The 267 pump bypasses @ 87psi while the 274 pump bypasses at 115. The high pressure feature is probably unnecessary.

Hodgdon Extreme · Apr 14, 2022

A few thoughts on the pumps themselves:

If the 525 and 535 pump are the same externally, why not use them? Two reasons:

First, the 525/535/Hellcat pumps only significantly outflow the 450 at low pressure. If you set your base fuel pressure to 40psi, have a manifold-referenced fuel pressure regulator, and then add 20psi boost - you'll be looking at 60psi of fuel rail pressure. When you consider the pressure losses through the filter and lines - it's likely the pump will see 70psi of backpressure. So when comparing pump flow charts, be sure you are comparing pumps at reasonable pressure levels you are likely to see in your car. At 70psi, the bigger 525/535 pumps offer only a small improvement.

Secondly, the 525/535 pumps draw a bunch more current. This means bigger wiring and more load on your alternator - but it also means more heat being introduced into your fuel. As your fuel heats up, its density changes - which will effect your air fuel ratio. It's best to avoid heating up your fuel as best you can.

Consider that electrical power = current * voltage

If you have a pump that draws 25 amps at 13.6 Volts, you'll be looking at 13.6V * 25A = 340 Watts

Law of conservation of energy says energy cannot be created or destroyed - only change forms. So where is that 340W of power going? Into your fuel as heat.

But Chrysler puts these pumps into the Hellcat stock! What's the problem?

Chrysler controls the fuel pump with pulsewidth modulation - so when the Hellcat is cruising around, the pump is only being run at 10-15% duty cycle. It's only when the engine is under boost that the pump is commanded to run full tilt.

Many ECUs these days have PWM drivers that can be used (and calibrated) to control a pump this way. If you know what goes into that and want to do it - that's great.

Pnut00 · Apr 17, 2022

Great write up, looking forward to hearing how it runs!

340W is quite a bit of heat to be putting into a small flow of fuel, i wonder if fuel line cooler would make any difference? I doubt it, but its a thought. A buddy of mine was running a mildly worked 350 Chev powered Holden on the strip years ago, he made up a fuel chiller of sorts with an ice bucket and a load of coiled copper fuel line as an experiment to see if it made much difference. I think he said there was some difference but it could have been an effect of cooling the engine bay, but he wasnt able to run it on the strip to quantify it as there was a high chance of it dripping water with the kind of launching he was able to do.

Hodgdon Extreme · Apr 21, 2022

Got the pump/hanger arrangement mostly done.

Had to trim the bezel to clear the new supply line and cable gland:

Considered setting up an auxiliary fuse/relay box in the trunk to power the new pump, but didn't have any other high power accessories in mind so instead just mounted the heavy duty relay under the back seat. There is a cavity in the seat foam directly above where I've mounted this relay, so the relay nests nicely up into the seat bottom.

I de-pinned the original connector for the hanger assembly so I could re-purpose the original pump power/ground wiring to trigger the new heavy duty relay. Power is the Blue/red-stripe and ground is White/black-stripe. Recall from my first post the fuel tank grounding/earthing points inside the hanger assembly are spliced into the ground lead for the original pump. I'll splice that pin of the hanger connector into the new pump ground lead that runs to a good chassis-ground (one of the rear seat-back hold-down bolts). I'm also considering splicing an additional lead that terminates with a ring terminal under one of the hanger bezel hold-down screws. I believe this will satisfy (and perhaps improve) the original design intent of grounding the fuel tank because the original wiring schematic indicates the pump ground lead runs to the left quarter panel.

I'm awaiting a 25 amp connector (Aptiv GT280) to connect the relay to the new hanger assembly, as well as a 30 amp fuse for the power wire at the main battery disconnect. Then I should be able to shrink the heatshrink and finish cable management.

More to follow.

Hodgdon Extreme · Apr 23, 2022

I'm having second thoughts on my relay/power arrangement. I'm considering switching to a solid state relay (SSR) so ecu can command a pump duty cycle. This will decrease the amount of current the pump is drawing most of the time, reduce fuel heating, reduce pump wear, etc ... Basically all good things. Need to determine if my ecu has a spare output I can use for this purpose.

Chrisgrunst · May 24, 2022

Did you finish this project I am doing the same I’m just getting on to the wiring portion

Hodgdon Extreme · May 24, 2022

Chrisgrunst said:
Did you finish this project

Mechanically it's complete, but I am implementing duty-cycle control via the new ecu.

If you do not intend to do it that way, all you need is a heavy duty mechanical relay, fed with (fused) 12awg (or heavier) power wiring from a suitable power distribution point. Trigger the relay with what used to be the fuel pump power wire (Blue/Red-stripe).

If it were me, I would remove the fuel pump resistor and splice the Green/white-stripe and Blue/Red-stripe wires together. This will render the OEM fuel pump relay pointless** and guarantee a good 12V trigger signal to close your new heavy duty pump relay. Thus, your new HD pump relay will close whenever the ecu closes the EFI relay and Circuit Opening relay. (which was required to energize the fuel pump with the stock configuration as well).

Place your 30A fuse as close to the battery as possible and be sure to use 12awg or heavier wire for both positive and negative power wiring!

You could also install the relay between pump and ground, rather than between battery and pump as shown in the schematic above. I know there are certain advantages/disadvantages for a relay to switch high vs. switch low - but honestly I don't really know what they are. Might be worth reading about. Come back and educate us.

** Note the stock "fuel pump relay" should really be called "fuel pump speed control relay" because it does not start/stop the pump. The pump is always energized so long as the EFI relay and Circuit Opening relay are closed by the ecu. The stock fuel pump relay is normally-closed, allowing current to pass unrestricted to the pump. However, when the ecu opens the fuel pump relay - current may still pass through the fuel pump resistor and to the pump - albeit with less voltage - causing the pump to run more slowly.

My recommendation to bypass the fuel pump resistor is based on a (small) concern that under light load, the ecu will open the stock fuel pump relay, forcing the current to flow through the resistor, decreasing trigger voltage to your new Heavy duty relay, and that might prevent your HD relay from properly closing as intended.

Hodgdon Extreme · Feb 13, 2023

I'm finishing this up; I need to hammer out a few details to incorporate my solid state relay which will allow me to control the fuel pump via PWM output on the ECU. This will allow me to calibrate the fuel pump to run easy for light load conditions and only run hard under boost conditions where fuel demand is actually high. This will avoid unnecessary current draw from the big Hellcat pump as well as unnecessary heating of the fuel - while still generating the required fuel pressure. It's worth noting that SSR relays leak a small amount of current even when switched off...so I'll also be using a traditional/mechanical relay to isolate the SSR when the ignition is off.

Anyway, solid state relays require a fast-acting suppression diode for inductive loads (like electric motors). Basically when power to the pump motor shuts off, the motor will still be spinning and therefore becomes a generator. That current needs a place to go. The diode allows that current to recirculate kinda like a recirculating blowoff/bypass valve on a turbo system.

The wiring diagram:

The SSR is capable of switching positive voltage, or switching to ground - which is why there are two arrangements in the diagram. But either way, the cathode of the diode must face the positive terminal of the relay.

The question is, how to implement?

My plan is to remove a section of insulation from each of my pump wires, perhaps 3/8" long. This would be done a few inches back from the connector (not shown in the picture below). Then use an open barrel splice to crimp the legs of the diode to the bare conductors. Then heat shrink over each leg of the diode. Then a piece of hot-glue heat shrink over the whole diode. Anybody have a better idea?

It did occur to me to simply crimp the diode legs along with the conductors when crimping the connector terminals. However, that won't work because the terminal is already maxed out with the 12AWG conductor of the wires; plus the diode legs aren't long enough to reach all the way through the connector from the backside.

AlwaysBroken · Feb 14, 2023

Are you using DC rated SSRs or the normal AC ones? Just wanted to make sure since the typical AC SSR will not handle DC loads well. I think you’d have to derate by a atrocious number like 80%.

As for the diode, as long as you have strain relief and it’s solidly mounted, it should be fine. Those legs by themselves are pretty flimsy. But heat shrinking the whole thing should make it work.

Hodgdon Extreme · Feb 14, 2023

AlwaysBroken said:
Are you using DC rated SSRs or the normal AC ones? Just wanted to make sure since the typical AC SSR will not handle DC loads well. I think you’d have to derate by a atrocious number like 80%.

I'm using a relay specifically for DC. I'm far from an electronics whizz, but I believe AC relays are totally unsuitable for switching DC altogether. I think AC relays rely on the zero volt crossover inherent to AC as a perfect opportunity to switch, which of course never happens with DC.

Hodgdon Extreme · Mar 31, 2023

Finalized:

How it's wired:

Seems to work nicely. The SSR makes a high-pitched hum, the pitch depends on what PWM frequency you call for. Pretty noisy below about 900hz; quiets down a fair bit by 1000hz. Pump did not flow less fuel at 1000hz, but I didn't test it with any real backpressure on the fuel system, so I don't know yet if the SSR can deliver enough current at 1000hz to move lots of fuel @ 65-70psi. We'll see.

Since envisioning this arrangement, it's come to my attention there are SSRs on the market intended for automotive applications more specifically:

This Hella unit plugs right into a traditional ISO-type relay socket:

HELLA
PART NUMBER: 4RA-931-773-98 or 4RA 007 865-031

They're rated at 22A switching current which means they can handle more at 100% duty cycle. The big Walbros can draw about 25A - so I think this relay would do the job.

Another option is the NOS/Holley SSR for nitrous control:

Part # 15620NOS

Rated at 20A switching and 40A continuous. I've read a bunch of good reviews about this unit.

There are also some SSRs for Chryslers that are pretty popular and work well:

Dorman 902-310 Engine Cooling Fan Relay Kit

Unsure on current rating, but fan motors draw a lot. Again, many good reviews on these.

somguy2u · Sep 22, 2023

Nice work, my battery is in the trunk and I went through this last winter as well.

one of the things to remember on picking an ssr is the switching speed. Many cannot handle much more than 200hz. Other things to think about is the inductive loading of the SSR is different than typical resistive, get a amp rating ssr that is 2x the anticipated load for safety ( i have read the inductive load should be 20% of the amp rating of the ssr - i think that is a bit extreme, if you notice it's not overheating your're probably good)

the best ssr's I came across that can handle higher frequencies on a budget:

Haltech SSR: HT-030202 Solid State Relay 100 AMP - Haltech
my personal favorite (though requires some more wiring) is the auber industrial: 80A DC SSR (50V), Low On-Resistance, High Switching Speed, PWM [SRDD80-5F] - $28.00 : Auber Instruments, Inc., Temperature control solutions for home and industry

It's "Rated" to 2khz, but the car didn't run well at 2khz, like you said 1khz seems to be the sweet spot.

They crydom you used is an amazing SSR - just crazy expensive

I did this for a very different reason - i use a single aem 340 but i was getting fuel overheating issues for my mountain drives (drive up, thrash it, drive back) and by the time i was half way through the mountain run it would lean out like crazy in boost. This helped solve that problem. I went straight from the battery on a 30amp fuse with 12ga wires and added an extra "fuel pump relay" right ont he end of the heatsink to turn it on that is triggered by the ecu. so i have two grounds to the ecu (fuel pump on/off relay and a pwm) the rest is battery, ground and fuel pump. I also utilized the factory connector that was repinned (i only used a 14ga power/ground).

AlexBerry10295 · Sep 10, 2025

somguy2u said:
Nice work, my battery is in the trunk and I went through this last winter as well.

one of the things to remember on picking an ssr is the switching speed. Many cannot handle much more than 200hz. Other things to think about is the inductive loading of the SSR is different than typical resistive, get a amp rating ssr that is 2x the anticipated load for safety ( i have read the inductive load should be 20% of the amp rating of the ssr - i think that is a bit extreme, if you notice it's not overheating your're probably good)

the best ssr's I came across that can handle higher frequencies on

It's "Rated" to 2khz, but the car didn't run well at 2khz, like you said 1khz seems to be the sweet spot.

This is all golden information, iv read this forum over and over and over disecting every detail i can. The only piece of information missing is where the Fuel pump connector ground (white / black) terminates or how it was used in the equation. The manual says LH quarter panel how ever iv unbolted that ground and still get continuity at the hanger connector to ground.

I want to utilise the OEM fuel pump power / ground wire to control the SSR in the boot. My battery is also in the boot so thats where it will all be located.

They crydom you used is an amazing SSR - just crazy expensive

I did this for a very different reason - i use a single aem 340 but i was getting fuel overheating issues for my mountain drives (drive up, thrash it, drive back) and by the time i was half way through the mountain run it would lean out like crazy in boost. This helped solve that problem. I went straight from the battery on a 30amp fuse with 12ga wires and added an extra "fuel pump relay" right ont he end of the heatsink to turn it on that is triggered by the ecu. so i have two grounds to the ecu (fuel pump on/off relay and a pwm) the rest is battery, ground and fuel pump. I also utilized the factory connector that was repinned (i only used a 14ga power/ground).

This is all golden information, iv read this forum over and over and over disecting every detail i can. The only piece of information missing is where the Fuel pump connector ground (white / black) terminates or how it was used in the equation. The manual says LH quarter panel how ever iv unbolted that ground and still get continuity at the hanger connector to ground.

I want to utilise the OEM fuel pump power / ground wire to control the SSR in the boot. My battery is also in the boot so thats where it will all be located.

Delbeke · Mar 24, 2024

What size fly back diode did you guys end up going with?

Hodgdon Extreme · Mar 24, 2024

Just needs to be fast-acting, and rated for the voltage and current.

I used this one: https://www.mouser.com/ProductDetai...tors/VS-60EPU06L-N3?qs=Fd5IDHV0Wqy4yaP74tqusQ==&countrycode=US&currencycode=USD

ConanOBrien · Aug 11, 2025

Sorry to revive an old thread, but did you need a heatsink for the flyback diode?

Hodgdon Extreme · Aug 11, 2025

ConanOBrien said:
did you need a heatsink for the flyback diode?

Nope!

Hodgdon Extreme · Sep 10, 2025

AlexBerry10295 said:
The only piece of information missing is where the Fuel pump connector ground (white / black) terminates or how it was used in the equation. The manual says LH quarter panel how ever iv unbolted that ground and still get continuity at the hanger connector to ground.

Post one says this, immediately before the 14th picture:

Hodgdon Extreme said:
The OEM arrangement has a grounding point and an earthing point spliced into the negative lead to the fuel pump. I clipped the lead off the splice that originally went to the fuel pump, and then clipped the positive lead off the fuel pump connector. I plugged the connector back in, the grounding and earthing points will still be connected to their original points in the car.

Pic 14 shows the spring-loaded ground point that contacts the rim of the hole the fuel pump hanger fits into. It's not a power ground (which is the LH quarter panel); but rather - a static electricity drainage pathway...

...but it'll still show continuity on a meter.

Perhaps what you're seeing.

Regarding power ground for fuel pump:

I set up my SSR to switch to ground - so the fuel pump ground runs back to the SSR. From the SSR, it runs forward to the OEM grounding point on the LH quarter panel.

I did that because I don't like the look of random ground points anywhere/everywhere convenient, and Toyota had already determined the quarter panel was a good spot... I assume they know how to implement "star point grounding" principles better than me - so I was just following their lead.

I already had a path to run a wire from pump to SSR; so the wire from SSR to grounding point simply follows same path.

AlexBerry10295 · Sep 10, 2025

Hodgdon Extreme said:
Post one says this, immediately before the 14th picture:

Pic 14 shows the spring-loaded ground point that contacts the rim of the hole the fuel pump hanger fits into. It's not a power ground (which is the LH quarter panel); but rather - a static electricity drainage pathway...

...but it'll still show continuity on a meter.

Perhaps what you're seeing.

Regarding power ground for fuel pump:

I set up my SSR to switch to ground - so the fuel pump ground runs back to the SSR. From the SSR, it runs forward to the OEM grounding point on the LH quarter panel.

I did that because I don't like the look of random ground points anywhere/everywhere convenient, and Toyota had already determined the quarter panel was a good spot... I assume they know how to implement "star point grounding" principles better than me - so I was just following their lead.

I already had a path to run a wire from pump to SSR; so the wire from SSR to grounding point simply follows same path.

Not so much the grounds on the actual hanger, im talking about both ends of the wire (Quarter panel and hanger connector) disconnected and still getting ground continuity.
I'm hesitant to use the factory OEM ground as I believe its not big enough for the pump alone, so I'll run a separate one to chassis.

I'm using Ecumaster Classic, and im pretty sure PWM outputs can only be positive in and pulsed to ground, if that makes sense, it won't pulse a 12v out (this is actually the case for most ECU's.) So I can't utilise the factory oem ground if its spliced in somewhere else in the chassis.

cwtt · Sep 10, 2025

I have also been rocking a similar setup.

Walbro 525 (Hellcat pump)
OEM Hellcat SSR
OEM IS300 fuel pump hanger

This works really well. The oem Hellcat fuel pump module was only$45 used. You can find them in tons of oem cars.

68193711AC

Walbro 450 or 480 or 525 or Hellcat fuel pump in IS300 stock hanger - also Solid State Relay fuel pump control

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