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Discussion Starter · #1 ·
Hooked up my CB. Works fine, until I start the engine, then all hell breaks loose. Loud steady constant noise, not varying with RPM. Turned off, then put key to ON position (w/o starting), noise occurred when the fuel pump was priming, then stopped. So I'm fairly convinced it's related to the fuel pump I put in about 6 months ago.

Any ideas (aside from dropping the tank to install a filter on the pump) on how to eliminate this problem? This is a YJ 4.0L.


Discussion Starter · #3 ·
The problem is antenna related - with it disconnected, and engine running, there is no noise. Noise only occurs when fuel pump is operating. RFI from the fuel pump. I need to get rid of!


· Registered
13,180 Posts
Hummm... you're in a world of hurt.... If you're an electroncics geek you could trap the frequency of the RFI and drain it to ground... but that's a hassle.

If the problem is indeed RFI then your limitd to:

1. Moving the antenna.
2. Shielding the pump.
3. Making sure the coax cable is intact.
4. Making sure all the grounds are in good shape.

Have you hooked up a buddies radio to the antenna to see if the 2nd radio also is affected by the RFI? Does the RFI emit far enough to interfere with a 2nd radio on another Jeep? If the pump is emitting that much RFI it may be going south....


Discussion Starter · #5 ·
Im going to try a handheld unit inside to see how it works. If that fails, I will try to bridge a capacitor at the connector near the tank for the pump. Ideally I'd like to do it at the pump, but this location is the best I can do without dropping the tank. If anyone has ideas on how to shield it without dropping the tanks I'm all ears. The antenna is mounted on the tire bump stop. The pump is 6mo's old, and the pump that went south gave off no RFI's. Doh!


Discussion Starter · #6 ·
Try using COAX as your power leads to both your fuel pump and CB, the COAX is sheilded and it may make the differance. I had the same problem with my radio's, I used COAX strait from the battery for the power leads(braided wire for the ground and the center wire as the + lead) the problem went away. Maybe using it for both the pump and radio's will work?

Good luck

Keep Jeep-n

75 CJ-5, 304, locked 44, 33X12.5 BFG's, Wheeling ALASKA

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