Fuel Pump noise thru CB radio...@ wits end.. - Ranger-Forums - The Ultimate Ford Ranger Resource


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Old 04-01-2012
JayBell's Avatar
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Fuel Pump noise thru CB [email protected] wits end..

2001 Ranger, 2.5 5spd, 2wd....

after searching, and reading a great many threads on the issue, and trying various fixes... I'm kind of at a loss on how to fix this...

I've run the + wire to the battery direct.
the ground is about 3" from the radio, direct to the body of the vehicle, and I've ensured the ground to the vehicle is good.
I've grounded the block, exhaust, and everything suggested.

my setup is a Cobra 19III mounted to the roof of the cab, with a K35 magnet mount on the roof, the coax exits the 3rd brake light.
the excess coax is arranged above the headliner, not coiled into loops.

the radio works excellently while the engine is off, but when the fuel pump turns on, might as well just turn it off, I have to squelch at 80% + to get rid of the noise.

any final suggestions before I just give up and kill it with fire?

thanks.
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Old 04-01-2012
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Where to start... Remove the coax from the rear of the CB and see if you still have the noise when the engine is running ?

If you do then it is in the electrical system and you can start with a filter on the power / ground wires.
Also, run the ground wire back to the battery also, use a loose wire first and see if this helps, if it does then there are two ways to do this.
One would be to take both the red and blk wires and twist them, 10 turns per foot and run them away from the driver's side of the vehicle.
Two would be to try a piece if coax for the pwr lead, center for the pwr and shield for the ground.

If,after removing the coax you find out there is no noise when the truck is running then the noise is air born and needs a different approach, a filter on the fuel pump leads.
I am not on my main computer and do not have the info with me but once you have tested out the power system for the CB I can get it.

I can not promise that these filters,will work but they can in some instances.

Luck on the testing, noise in communication radios can be a PITA.
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Old 04-01-2012
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Have you replaced the ground strap from the engine to the wiper motor?

Also the fuel pump grounds to inside the cab near the fuse box, check to make sure its tight too.

If you are using a mag mount antenna ditch it, and get a new coax.
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Old 04-01-2012
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If you haven't already done so, try installing an inline noise suppressor on the power feed. Additionally, If you're sure its the fuel pump read through these links. Click Link and Click Link
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Old 04-01-2012
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Quote:
Originally Posted by Rev View Post
This is the one I was going to suggest but just got to it; it does work and should help a lot.
Also, here is a filter for the main power wires, I did not design it but it too works well and home built.
It is titled Alternator Whine but it works on a lot of white noise.

Can’t seem to get the doc to download so if you want it send me your e-mail and I will send it to you.

[email protected]
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Old 04-01-2012
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I've tried all the above suggestions(regarding various dirty electricals, or grounding issues, or other power issues) before I posted here, this noise is fuel pump...

turn radio on. turn key to on(but not start), the second the fuel pump goes on theres the noise...its as described in this link... http://www2.97vette.com/sporttrac/rfi_fix/rfi_fix.html

with the antenna unplugged, no noise of any kind comes from the radio

the K35 antenna is brand new, and I've run a K40 for years on another vehicle, this is not some POS bottom loader from Ronco... "ditch it and get a new coax " is not a valid solution, and leaves me with no antenna at all, with bed rails and a tonneau, I dotn have another option aside from a firestick off the hood mount, and thats a ugly NO... and I'm not drilling my body panels for a 102" ball mount, or any other mount.

I guess I'll have to try the inline filter on the fuel pump leads, I added a toroid to the main power feed with no difference in signal.

thanks for the assistance all, maybe the pump lead toroid will work...
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Old 04-01-2012
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You can try all of the above and still have the noise, every vehicle is different.
Could be as easy as moving the antenna, try that mag-mount on the hood and see if you get the same noise.
While you are under there adding the in line filter, chk the grounding for the tank.
If you can add another ground from tank/fuel pump area to frame...
Get good bare metal connections and if possible add some dielectric grease on all connections.
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Old 04-01-2012
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Just so you know, leaving a mag mount in the same spot for a long time will cause the spot under it to not age like the rest of the paint... thus a weird circle will be there after you pull the antenna.

Get a toolbox and mount the antenna to that. See my bracket in the "what's your unique mod" thread.

Or keep moving that antenna around every now and then.
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Old 04-01-2012
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Quote:
Originally Posted by Scrambler82 View Post
This is the one I was going to suggest but just got to it; it does work and should help a lot.
Also, here is a filter for the main power wires, I did not design it but it too works well and home built.
It is titled Alternator Whine but it works on a lot of white noise.

Can’t seem to get the doc to download so if you want it send me your e-mail and I will send it to you.

[email protected]
You have my email.. could you send that to me as well?

Thanks.
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  #10  
Old 04-02-2012
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I am by no meant a CB expert but I know that there is a Technical Service Bulletin for rangers that talks about hearing fuel pump noise through your stock speakers. Possibly a similar kind of interference with your CB. I'll see if I can find a copy that I can post here if you want...
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Old 04-03-2012
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1996DangerRanger,

When I get home around noon I can send it along, the ford one and the power line filter.

Not sure on the e-mail addie ?

Last edited by Scrambler82; 04-03-2012 at 06:50 AM.
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Old 04-03-2012
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