Controlling an automotive fuel pump with a PWM - HELP!

First off…please excuse my fat thumbs…my username was supposed to be ls67nova but I flubbed it when I was setting up an account haha.

Ok, newbie here… so to start, I’ll come out and admit I’m very under-knowledged when it comes to this stuff. Also, I’m not building a robot, rather I’m ready to re-work a fuel injection system that I retrofitted into my 67 Nova.

Currently the fuel pump is driven by a PWM…which is no longer available on the market. There are a couple others, but their price is prohibitive. So I’m looking to build my own.

The system works by having a fuel pressure sensor in the fuel rail. The system runs at 58psi. The sensor is set to output 0-5VDC based on 0-100psi of fuel pressure, so my assumption is that 58psi would equate to 2.9VDC being output from the sensor. The PWM is setup to maintain this 58psi in the system at all times. During fuel demand (hitting the throttle), the fuel pressure would drop (the sensor’s output would drop) and cause the PWM to make the pump speed increase to increase the pressure back to 58. Once the pressure hits 58, the PWM holds the pump at that speed. When the demand is gone, the pressure would start to rise and the PWM would tell the pump to slow down.

So basically the PWM makes the pump adjust it’s speed to maintain 58psi on the system (or approximately 2.9VDC output from the fuel pressure sensor).

My questions are:

  1. Would the RB-CYT-133 be a suitable PWM? I’d only need 20A max, so 30A should be plenty.

  2. And what would I need to make the PWM run to maintain that 58psi?

The second question is what is most confusing to me. I think I can select from many PWMs that put out 12VDC (or 14.3 for automotive, etc)…but it’s the task of maintaining the fuel pressure that confuses me. There are other models on the market that use a 0-5VDC sensor from things like the Throttle Position Sensor (TPS)…as the TPS increases (driver pushing the pedal more), the voltage increases into the PWM, so the PWM speeds up the pump. But that type of a system requires a fuel pressure regulator, return line, etc. The system I’m trying to replace needs none of that because it maintains it’s own pressure at 58psi.

Any thoughts or help are greatly appreciated!!


Yes, it most certainly seems like the RB-Cyt-133 would meet your requirements in both voltage and current. Please note that this product is designed for hobbyist/DIY robotics and not automotive use. Therefore, it may not be adequate for that environment. That being said, it would certainly be sufficient for a prototype / proof of concept.

Typically, a control system is used to control an output based on input/feedback related to the output. There are many ways to implement a control system, but one of the simplest for your case would be to use a small microcontroller to read the input, process it and produce an output to the motor controller (which then feeds the motor of the pump).

For simplicity, we’d recommend going for a simple Arduino-based microcontroller that supports a voltage source of ~12 V DC.

The complete system would look something like this:
SUP - 2017-09-13 - Pump control system.png

We hope this helps!


Thank you for the reply!!! (I also saw your latest emaii response as well, so thank you!!)

In reading about the arduino, it seems that the software needed to do the program is pre-loaded in the microcontroller? So when I connect a laptop via USB, then the necessary software will load on my laptop and I’m all set to start programming?

And yes, this will be a prototype/conceptual type of project for now. Just want to see if I can make this work!!


Never mind my last post…I found that you need to download the software online.


You can find all the versions here.

Thanks again!!! I looked back at my pump info and saw that when I tested it in 2012, it maxed out at 9.0 amps…so I chose a smaller controller to save a few bucks for my first attempt. I went with the RB-CYT-132 instead which is rated at 13.5 amps continuous. Can’t wait to get started!! Thank you for your help!

What a great project to restore, I’m a petrolhead myself so know my way round an engine bay and ECU nowadays.

Looking at what you need I’d have thought it’d have been easier to go down the route of an aftermarket ECU you can setup yourself. That way you can add in more systems to be controlled by the ECU depending on far you wanted to modernise things. They’re a little pricer than doing things with your own micro controllers but they’re specifc to automotive control and if you swapped ou the engine the same ECU can be setup to handle any new engine, most have integrated ABS and ESC/Traction Control and things as well which will allow further stuff in the future. I’d imagine that motor is worth waaay more stock if it’s a restore and sell project but if you’re keeping it it might be worthwhile looking up aftermarket ECU’s- there’s a couple of manufacturers and each has their speciality.

Just my 2 bits anyway matey- be lovely to see that bad lad back to it’s shining glory.

My engine is from a 2002 Camaro, and the ECM doesn’t have much control of the fuel system except a “turn on” wire that acts as a relay wire to turn on the fuel pump. I’m pretty sure that the newer LS based engines have a LOT more ECM control of things like that though!

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Great project @ls67bova … how did things work out?

Would this controller work for you? LINK

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I’m assuming that he figured it out since it was 2 years ago. That said, I am curious what the end product looks like and how it works.

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Thanks for this information. It useful

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