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Old 07-03-2013, 02:50 PM   #1
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Engine RPM Drop when Trasmitting

When I key the CB mic, the engine runs rough and starts to die.
It will die if talk some and I don't hit the accelerator to rev it!

Anyone know the solution?

RJ

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Old 07-03-2013, 03:06 PM   #2
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Originally Posted by RowJ View Post
When I key the CB mic, the engine runs rough and starts to die.
It will die if talk some and I don't hit the accelerator to rev it!

Anyone know the solution?

RJ
Sounds like you're puttin out watts and watts and watts of power! Haha

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Old 07-03-2013, 03:16 PM   #3
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where did you tap the power fo the cb?
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Old 07-03-2013, 03:22 PM   #4
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Is your cb circuit fused? Sounds to me like there's a very high amp draw when you key your mic. Either and internal short in the cb/mic cable, or too small of wire feeding the cb causing low voltage and high amps.
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Old 07-03-2013, 03:46 PM   #5
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I read a few post somewhere that the Antenna mounted on the rear bumper was causing simular symptoms. Not sure why. if you are mounted on the bumper pull it off for a quick test.
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Old 07-04-2013, 12:20 PM   #6
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where did you tap the power fo the cb?
Ran it straight to the battery
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I read a few post somewhere that the Antenna mounted on the rear bumper was causing simular symptoms.
I am on rear bumper but so are thousands others....and I have had no problems for last two yrs!
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.... or too small of wire feeding the cb causing low voltage and high amps.
Had no problem for last 6 months.... problem started all of a sudden last weekend!
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Old 07-04-2013, 01:39 PM   #7
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Are the battery posts clean and terminals connected well? I would also try unplugging everything from the battery for like 10 minutes to reset everything and try again.
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Old 07-04-2013, 01:46 PM   #8
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I'd double-check how well the antenna mount is grounded to the tub or whatever it is grounded to. An RF ground that was marginal to begin with can become weak or non-existant with time.
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Old 07-04-2013, 11:25 PM   #9
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Back when fuel injection/computers started comming out on american vehicles there were lots of drivability problems-some happened because of CB's and especially with a Linear. the TFI ( thick film ignition) module in the distributor or the wiring going to it was not shielded enough. Interference from the CB radio wavelengths made the ignitions go bananas, and many times just quit-although it would re-start. however it is also possible you have wired in the CB and ran wire parallel as opossed to across the wiring harness. This also created problems. Look for areas on your wiring harness has been un-wrapped, exposing some of the foil looking wrap inside. Especially if this part of the harness is out under the hood.Hope this helps
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Old 07-07-2013, 11:53 AM   #10
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Found the problem....after 2 hrs of tracing and inspecting every wire and connection! Problem was intermittant.... sometimes killing an idling engine completely and sometimes just dropping rpm's a few hundred and running rough. So I went in search of a loose connection.

Found one. Where the coax screws into the radio.... the center section of the coax (hot wire) was loose in the center pin (that inserts into the radio). My plug has a locking sleeve over the hot wire that holds it into the plug. Tightened the locking sleeve and problem solved.

SWR 1.15 at both ends of the band and....
Not more rough idle or killed engine when transmitting!!

RJ
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Old 07-07-2013, 12:19 PM   #11
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Good work but that center conductor isn't soldered to the plug's pin? I'd go back and solder it.
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Old 07-07-2013, 04:36 PM   #12
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Good work but that center conductor isn't soldered to the plug's pin?
Exactly my thought when a minor rpm drop reappeared!
Went to a local ham friend and got him to put on a soldered PL-259 connector for me.

The factory mass installed connectors have NO soldered connections at all!!
Shame on Firestik for that. But my buddy did say they cut no corners nor shaved any expenses on the coax cable.

RJ

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