2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

s4 na: humming noise from tb no start

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Old Sep 7, 2012 | 02:57 PM
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From: Dirty Jerz
Unhappy s4 na: humming noise from tb no start

So I took apart my upper intake Mani to paint it. After that I reinstall everything in its proper place I went to start it and it crank and cranked, started but died as soon as it did. Whens I went to the throttle body it was making a humming noise like a bad relay sound. When I touch the throttle linkage it goes away and happens when key is on engine off.

Do I need a new TB? Please help me out guys thanx
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Old Sep 7, 2012 | 03:35 PM
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From: Czech Republic [www.rx7cz.net]
for start and die check your AFM plug

humming noise is most likely BAC and there is nothing wrong with it...
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Old Sep 7, 2012 | 04:02 PM
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From: tulsa,ok.
If the unplugging of the BAC stopped the hummimg then you know the source.
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Old Sep 7, 2012 | 05:26 PM
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From: Smiths Falls.(near Ottawa!.Mapquest IT!)
Duh!..Its a Thirteen BEE!
(Sorry,I had to say it..I just had to!!!!!)
..Seriously,Higgi and Satch got a grip in this one..BAC.
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Old Sep 7, 2012 | 06:07 PM
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From: Dirty Jerz
Ok thanx guys good thing I got another bac ill swap em out when I get home
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Old Sep 7, 2012 | 06:16 PM
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From: tulsa,ok.
It's normal for the BAC to hum so replacing it is not necessarily a fix.
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Old Sep 7, 2012 | 07:25 PM
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From: Dirty Jerz
Could it be the tps? And is there a way to test the bac?
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Old Sep 7, 2012 | 07:32 PM
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From: tulsa,ok.
Again, if the BAC were humming/vibrating and you unplugged its electrical connection and the noise stopped then you know the source of the noise.
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Old Sep 7, 2012 | 11:02 PM
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From: Dirty Jerz
Ok I swaped out the bac and ofcourse nothing when I disconnected the tps it stopped humming could it be the tps or this means nothing??
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Old Sep 8, 2012 | 10:40 AM
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From: tulsa,ok.
The TPS controls both the Relief and Switching solenoids. The Relief solenoid has a circular blue mark on it. It has a plug w/two wires. Unplug this plug when the humming occurs. If the humming still occurs then unplug the Switching solenoid plug.
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Old Sep 8, 2012 | 12:08 PM
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From: YYZ
Once again...humming is normal. Unplugged afm or maybe hose unattached...check one that connects from the bottom to snorkel between air box and tb. Dont readjust tps and it was mentioned not to swap bac. Focus on stuff u undid or disconnected.
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Old Sep 8, 2012 | 12:42 PM
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From: And the horse he rode in on...
Originally Posted by pfsantos
Once again...humming is normal.
And the humming isn't keeping the car from starting.

The no start is normal, if you have a major vacuum leak.
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Old Sep 10, 2012 | 12:18 PM
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From: Dirty Jerz
Ok so the humming means nothing but it still wont run. I checked all vac lines even underneath the Mani and they're all good, deflooded it, changed spark plugs and still nothing. Sometimes if I crank it long enough it starts, revs to 4000 then dies.

Any ideas guys?
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Old Sep 10, 2012 | 12:29 PM
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From: Czech Republic [www.rx7cz.net]
have you checked your AFM plug (if its properly connected?)
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Old Sep 10, 2012 | 12:56 PM
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From: tulsa,ok.
Have you tried jumpering the fuel check connector?
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Old Sep 10, 2012 | 01:03 PM
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From: Dirty Jerz
Afm plug is fine

Satch; how would I do that?
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Old Sep 10, 2012 | 01:30 PM
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From: tulsa,ok.
Under the dash and just to the right of the steering column is a Black and Yellow relay/plug called the Circuit Opening Relay. Has two rows of wires. Bottom row has two wires, one Black and the other Brown. Jumper these two wires together. W/key to on the Blue wire in the top row far right position should have voltage. This wire powers the fuel pump
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Old Sep 10, 2012 | 02:26 PM
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From: YYZ
^ or you can just jumper the yellow connector under the hood near the intake with ignition on.

Pictures of Fuel pump connector, Circuit opening relay (the one satch mentions), etc.:

https://www.rx7club.com/2nd-generati...erence-671004/
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