FUEL PUMP RFI ( ham radio related)

In automotive electronics, RFI is huge. You do everything possible to avoid RFI spewing into FM Band.

I'd still be curious to hear what happens with subcircuits unplugged.

One fuse a time. If you have an optional AC power, pull that fuse.

Thankfully pulling out one fuse at a time, while time-consuming, won't hurt anything.

I have my SDR (software-defined radio) Stick around here. It would be interesting to scan the spectrum with the truck off and running and capture the screenshots. I keep telling myself, "no way could Toyota screw up that badly, but something is spewing that RF," but I've seen it.

Older 12V brushed fuel pumps did make noise, but with the 3rd generation fuel pump and ECU (expensive cost adders!) I would love to know the engineering that went into that solution.

Cal Poly SLO. Got my BSET/EL there in 1983. Active with the local ham club. We had a game of "find the transmitter." Backpacks with ham gear, and you're on foot. Hound and rabbit, you tried to find the transmitter—so Broad and directional antennas.

The local TV Cable company had complaints of "lousy reception with cable, it was better with over the air". The CEO had a commercial spot to explain it was local hams causing the interference. Yep, he saw the power of spreading misinformation via his cable network. Every Ham was burning mad with this. So it was a new "hound and rabbit" game to find every source of cable TV leaks.

They had used poor quality coax, lousy connectors, and noisy distribution boxes. We created some neat gear for tracking and lots of fun with professors helping and writing a wonderful report for the FCC. The cable company said, "we are not over the air; we don't have to comply". Not so fast, FCC came down hard with penalties. They ended up having to replace all the cables and connections. Consumers had much better TV quality, hams had much less interference.

Sadly the FCC was force to be "for sale to highest bidder" for Bandwidth, and the foxes were left to watch the henhouse.

Only way to get Toyota to respond would be to have a test chamber that the whole vehicle can drive into and be sniffed for RFI emissions. They exist, but you need to find someone with no affliation to do the testing, which is a huge challenge.

Meanwhile, second battery, ton of filtering into and out of that battery. Ferrite beads and LC trap filters into every power item (i.e. radio). Keep all wiring shielded (you only ground shields on one end).

It got my FCC 2nd class license in 1980, lots has changed since then. I need to get back into ham, but my time is spent on keeping alive (hiking, biking, swimming, boxing). Only way I keep my Parkinson's in check is intense exercise. Hmm, thankfully modern electronics have gotten much smaller and better. SDR still blows me away, just way too neat.

Enough crazy ramblings for this morning. Yes, I used to teach classes and loved my days in the field at customers. Some of the most painful, but rewarding, days were spent in Anechoic Test Chambers. They would start off with "hey why are we failing FCC testing?" I got a big cup of coffee before calling those customers back. No simple fixes, lots of little things. Some of those took months to resolve, but you rented chamber time so it got expensive.

 

For those of us that love remote camping & back packing. Ham radios and repeater can be life savers.

I have zero interst in yaking, but still keep my Nato Alphabet in use. Dash cam, when a car flies past me I read off "Papa Mike Tango Too Fife Zero White Toyota Camry" from the plate. If I come across a hit and run, I can repeat that to local PD. Much better than saying "late model white sedan"

So repeater and having a ham radio off the beaten path means saving hours to get someone help. Time for me to take a CPR and first aid refresher.

 

It’s already been narrowed down to the fuel pump by unplugging the fuel pump ecu output ( which feeds directly to the FP) and running the vehicle with the residual fuel in the lines and the RFI went away.

 

For a giggle, unbolt the fuel pump ECU. Clean up the mounting points on both ECU and frame, use a little anti-seize, bolt it back together.

Retest and compare.

I went back and looked at you have a 2016, so wondering "what has changed in the past six years". Corrosion is possible, but normally if 15 years old it would be more likely. Five or six, not likely but worth testing.

Have you probed the lines to the fuel pump? A B C so isolated scope between A & B, then B & C, then A & C. I'm still not 100% sure if that is a three-phase pump (I suspect it) but could be a 12V pump with power and ground, and ground connection to the pump. Harness and wiring imply three-phase, but I've been wrong before.

There is an IC that takes a PWM waveform and creates a three-phase waveform for a permanent magnetic (PM) motor. I have zero knowledge of what Toyota does but that IC has built-in waveform shaping to prevent radiated harmonics (square wave will slew rate limit rising edge and clip corners).

The ECU monitors fuel pump pressure. So with the pump disconnected, the pressure sensed is off (you should have seen a CEL and have an ECU code show up on a Techstream). Yep, low pressure goes into limp home mode. A whole lot of little differences.

My idiotic maneuver was testing an ECU in "hardware in a loop". I could modify engine temp, rpm, air pressure, battery voltage fuel pressure, etc. (all stimulated externally). I would then monitor ignition timing and fuel injector pulse width. I screwed up in the computer had too much intelligence. When I varied engine temp too rapidly, the ECU knew "faulty sensor" and would reduce power to prevent engine damage. Took a while to figure that one out. So disconnecting the fuel pump, the ECU knows and goes into the limp home mode (hint not normal operation). You can spend weeks chasing your tail! Yes, been there and done that.

So think of onions, keep peeling layers to expose more ideas followed by more testing and peeling another layer. Just be grateful you're not in Austin, TX and the onion is in Dunton, UK. Thankfully I got to fly business class those days!

 

no idiot
Lights came on when I rant it with the ecu unplugged. But I also didn’t run it dry either. I did one or two starts to verify then plugged it back in.
I did not scan for any codes that may have stored but not triggered the idiot light.

I’ll try pulling the plate that armors the ECU and the ECU and check for good bond/ground but when I sniffed with the SA , the noise was not as strong when I checked towards the front or along the frame , but peaked center of fuel tank.

 

just pump and blow , or even just pump honestly , a proper chest compression will move the lungs enough. Oh and if you aren’t cracking ribs , your compressions aren’t proper

 

Am I late to the party ?

 

He lives

 

I’ve taken a break from this for a few weeks, was finishing up some other RFI issues from the local area at home .. funny how I installed an HF rig in my work vehicle ( transhit 250) ft-891 and atas 120 a and I have virtually ZERO rfi from that tin can. Same type rig and antenna.
Ford managed to get this shit right. Wonder if I should trade the taco in on a ranger

I still never received a call back from Toyota. Might be time to start calling again.

 

well after this thread went cold i had a thought that might be interesting to you, so i'll throw it out there in case it is.
RFI is coming from the PWM pump (as you originally suspected) but there is really no way to shield it.
except...maybe...there is ferrous/magnetic paint...it can be pricey but there are many options and maybe something would work for you.
i have used it in the past to quiet things like electric guitar electronics cavities, etc. works really well.
you might paint the gas tank with it and try grounding or not grounding (faraday).
probably would requiring getting to all of the tank so this could be rough to access...but a thought...and certainly after all other options exhausted.

 

I've read the thread about the noisy fuel pump. You are not alone, I have the exact same problem.

Mine is a 21 MT 3.5L Access Cab 4X4 Sport with a Codan Sentry HF-SSB transceiver. Antenna is mounted in the rear left corner, on top of the overland rack and there is an ATU at the base. The radio is unusable when the motor is running on any frequency above 10 MHz.

The noise goes away when the grey line to the fuel pump is disconnected from the fuel ECU located inside the frame under the drivers side doors.

I have done much of what the OP has done. DC power system is correct and has ferrites. Radio equipment is grounded. I am convinced this is not DC related, rather is emitting RF and being picked up by the antenna system. Disconnect antenna, noise goes away. We have used the truck for HF work in the past, but in those cases the antennas were on masts some distance away.

I have a regular service appointment tomorrow and I'll bring this up (not that I expect that will do any good - I can already picture the blank stare from the service manager).

 

As soon as warranty is up, im dropping the tank, adding a few mix31 ferrite rings on the harness. Mix 31 is rated for 1-300 MHZ and the more turns, the more suppression. UNless Toyota acknowledges that their fuel pump is exceeding the FCC limits of an incidental radiator. Id be curious if they were ever tested by the manufacture for compliance.

 

They will stick to the " its not factory installed, its not our problem" ..

 

Just catching up on this thread. Installed an Ft-891 like the OP did. Mounted two antennas on a ‘backrack’ , on the passenger side, a dual band 2m/70cm, and on the driver side a quick disconnect hamstick setup. I had a lot of ignition noise and was able to get that cleaned up about 90% with mix 31 clip on ferrites on the 12V DC feed. 3 on each lead. I have 4 mix 31 clip on ferrites on the coax feed.

I’m having S5-S9+10 noise on the 20 band as well. I have to turn the IPO on to try lower the noise.

I no longer need to have the noise blanker on.

2021 Tacoma 4 door.

MFJ sells a noise cancellation device that may be worth looking into. I remember seeing it before. From what i understand, it will ‘counter phase’ offending noise, flipping it 180 deg and adding it to the stream. I’m also wondering if it will dynamically follow the offending signal as the PWM changes.
https://mfjenterprises.com/products/mfj-1026

 

Those noise phase units require a second antenna to be able to cancel said noise and can be finicky to tune. Not sure I’d want to be screwing with that much while in motion.

I’ve toyed with similar stuff home using my RSP duo , while that has some automatic features, it does tend to work.

one problem with that would be as the fuel pump speed changes based on fuel delivery demand , I feel you would be constantly chasing the dials.

I’ve since moved onto redoing the shack at home since the taco only gets driven on the weekend right now. Maybe come spring I’ll tear into it more.

 

You can filter it with an LC filter at the fuel pump if you so feel inclined. It involves a bit of soldering, and you need to make sure you do it properly as to. It disturb the pwm signal. If don't properly it'll actually clean up the pwm signal.


Also, for shits and giggles, if you haven't already make sure to select IPO which turns the preamp off and should resolve a good amount of noise.

 

Yeah IPO displayed , the LC would be a bitch cause it’s 3 wire ( basically 3 phase)

can’t just use a capacitor across to ground.

it’s on my list of things to revisit come spring. Right now I’m redoing the shack wiring, grounding, bonding etc

 

It seems to me it could still be the pump ecu. If it's the pump ECU, the noise is using the harness and the pump as an antenna. You disconnect the "antenna" when you disconnect the pump from the pump ecu, and the noise is gone. I wonder if you could sleeve that harness with a shield and then ground the shield at both ends?

If you really believe the truck is not FCC part 15 compliant, you should file a grievance with the FCC. When dealing with the dealer, claim that the truck is interfering with public safety (SHARES) and military (MARS) communications systems. If a public safety VHF / UHF / 700 / 800 radio were effected, they might take some notice? It's not about factory installed equipment. The truck is not in compliance with federal regulations.

 

This. I have an IC-706 partially installed, and was hoping to do some HF out of my '19 OR. This thread makes me wonder if that will be possible. If the noise is that bad, I'd be curious how the truck passed EMC testing.

 

Any updates? I've been bonding my setup in small increments over the past week. When the engine was running before the bonding, 20 meters was wiped out. It seems the noise floor has been getting lower with each strap added. The fuel pump and/or pump module, like mentioned by others, is the only culprit for me at this point. I bonded the rear of the exhaust today, but I haven't re-tested.

On a side note, the bonding has improved the UHF radio also. It's been slowly improving as well. I guess it was taking on more interference than I thought. The LED headlights were causing desense/"hash". I could turn the headlights on and off while receiving and "hash" would follow. After installing the strap at the end of the exhaust today, it's totally gone. I honestly couldn't believe it.