FUEL PUMP RFI ( ham radio related)

My fuel pump spews an ungodly amount of RFI on the HF bands.
I’ve bonded the hell out of the truck and still can’t get rid of it or get it manageable. My next step is some mix 31 toroids on the fuel pump wiring harness, but have some questions.

1. Does the pump on the 3rd gen ( ‘16) use 12v constant to power the pump when running or does it use some sort of pulse width modulation to change the speed of the pump in relation to engine rpm?

2. My plan is to take 2) mix 31 toroids and wrap as many turns on each respective wire ( + and -) as I can fit to eliminate the noise from the pump being radiated through the wiring that is acting like an antenna and also a capacitor across the leads.

To do this, I will need to add about 12-15” of wire to the harness , BUT I do not want to cut into the factory harness. So I plan to acquire the respective male and female plugs , so I can add my filter circuit in series, but will be basically a plug n play if you will.

Does anyone have any of the technical knowledge of the fuel pump circuit to verify its power ?

My concern is if it does use some sort of variable speed , by adding the toroids and capacitor ( LC circuit ) would it affect the signaling , if any, to the fuel pump?

 

Not a tech or an engineer, but in reading the service manual and OVtune information regarding the low pressure fuel pump, it definitely uses PWM. It's a return less system that varies fuel pressure in real time according to demand. There's a control module on the frame rail that deals with the LPFP. You may get away with the torroids, but I would not try putting a cap across the pump leads.. FWIW

 

Might also try shielded cable?

 

Makes sense with the capacitor of this is how it’s setup. Now this makes me wonder if the RFI is between the pump and the module or between the module front …….

 

Shielded cable where? It’s not being picked up through the power leads , as I already have that filtered. It’s being picked up from the antenna, if that helps..

the noise is not there when the antenna is disconnected. I’ve verified that by disconnecting the antenna from the mount ( verifying it’s not being picked up via the coax between the RF deck and the antenna mount)

 

Shielded cable between the pump ECU and the pump connector at the tank? Since you were talking about torroids and adding a length of cable anyway..

 

So you get this interference with key on/ignition off? Only as long as it takes for the pump to do its initial spin up?

 

I got ya, yeah I could use some shielded there, in that case , I’d have to run two separate ones ( I’d like to separate the power and ground in their own toroids) then I could bond the shielding as well.

 

I get the hash/trash when the fuel pump primes , then it drops when the FP shuts off ( if i put the truck to accy mode ) and if the vehicle is running, and I kill the ignition , there is a a delay for the noise to stop about a second after the engine stops ( when the fuel pump kicks off).

 

I guess the thing I need to do is try and isolate if the noise is being generated between the input of the fuel pump ecu ( on the frame ) or between the ecu and in tank pump.

I’ll have to dig out my inductive wand I have from my old telco line toner and see if that picks up the noise while probing the respective harnesses..

I’m wondering if I disconnect the plug at the fuel pump and run through the ignition cycle steps , if the computers will still send the signals to prime the pump or if the system is smart enough to know the pump is disconnected , and not attempted. And then try the same method working my way back to the input to the pump ECU input harness etc trying to divide and concur.

 

Hmmm, was just using a fox and hound kit (and butt phone with bix clip) the other day tracing an audio logging cct... for which someone lost the cable records years ago lol.
It would be interesting to see on a spectrum analyzer just how much garbage is being splashed around when the fuel pump is active, and how high above the background grass it rises...
I assume you've played with settings in your transceiver if available (filters, IF bandwidth etc).

 

Yeah, I run NB and preamps off, but it still annoying AF.
I have a tiny SA. Let me fire that up and see if I can get some screen shots of the noise floor pre and post ( non started / Started).

 

It’s not the best , most accurate device, but it hasn’t been calibrated , but it gives you an idea

https://www.youtube.com/watch?v=ICAhlBrbsSs

 

Where did you mount your antenna? I am planning on adding a 2m/70cm radio and hope to try and avoid the problem you have described. Also, any details on the antenna you used would be appreciated. See you on the air KJ7COX.

 

https://youtu.be/VywIAhc6rOQ

 

My vhf/ uhf is mounted front left fender with NMO mount. No issues with that.
HF antenna is mounted right rear

 

And here is another view using another type of spectrum analyzer. It’s not a communications analyzer , but you can still see a difference in the noise

my apologies , I meant to say 14 MHZ or 1400 KHZ, NOT 1400 MHZ for the purists out there

https://youtu.be/aCzK2s_Bp5c

 

Following. That's some significant RFI!

 

That’s why it pisses me off so much

 

Id imagine that you would get better advice at the Ham Thread...

https://www.tacomaworld.com/threads/amateur-ham-radio-bs-and-callsign-thread.260643/