What is that NOISE?

NapTownSpeedy · 07-15-2002, 06:49 AM

Help me Please!
I have a low level, electrical sounding hum in my car.
Now here is what I've checked:
It is not the buzzer for the seat belts or the brake warning. Those turn off.
It is not the door ajar buzzer either.
The PO did a hack job install on an after market stereo. I know it is not connected correctly. But I don't think that's the issue.
My brake warning light stays lit. But I disconnected the battery, let the thing reset and the noise was still there. (warning light did come back on, I will still try to find the source of this gremlin).
The noise it self is a low tone, constant sound. It doesn't chage in frequency or intensity with engine rpm or road speed. It sounds almost like it is comming from behind the pedal cluster. But no change when either brake or clutch is applied.
So what gives? Any ideas are helpful.
Looking forward to the Tweeks event this weekend. If it isn't sorted by Saturday, maybe one of the attendees might give a listen.

Targa77 · Targa77's Garage

A bad ground for the stereo system will cause this. I would have an audio pro look at it. Could be that he can zoom right in on the problem.

Tim L · 07-15-2002, 07:04 AM

fuel pump?

Tim

NapTownSpeedy · 07-15-2002, 12:36 PM

Okay, so since the suggestion of the fuel pump I have done some checking. Seems like the board has answered a bunch of these questions before. My guess is that it is probably the fuel pump.
The noise only happens when the engine is running. If it were radio related, wouldn't that happen with the key in the accessory position?
Car runs like a champ now. Most threads state there is no other warning for pump failure. Anyone have thoughts about if the whine/hum will intensify, or will she just crap out one day?
Thanks for putting up with me, I'm still learning.

wcballance · wcballance's Garage

I replaced my fuel pump with the aid of a friend not too long ago. My car was also running fine, but the noise had just gotten too loud for me. I was told by a mechanic that a little hum was normal and that I could replace the pump, but expect it to go back to humming within a year. Well, if I listen hard enough I can hear a small whine now but it is nothing compared to what it used to be! If you can hear the whine while driving on an Interstate with the windows down you are probably in the same situation I was and I'd say it's time to replace it. When mine came out you could shake it and hear a noticeable rattle -- I can only assume that is a bad thing since the new one didn't rattle at all.

The job isn't all that bad, but be careful not to get gas in your eyes while under the car. If you do the job you find yourself wanting smaller hands.

Good luck.

---
Will Ballance
'82 911SC coupe

slakjaw · 07-15-2002, 03:19 PM

wouldent the fuel pump come on when the key is on, motor running or not??

Early_S_Man · 07-15-2002, 03:43 PM

slak ... there must be airflow, or the starter must be cranking for the fuel pump to recieve power!

Fuel pump noise can increase significantly if the fuel filter is partly clogged due to a rust/contaminant problem in the fuel tank ... and current drain of the pump will increase as it strains. Worn pumps near their useful life also can draw more than the spec book maximum of 8 Amperes ... even if the fuel supply line is unrestricted! Doug Z. reported that a failing pump he replaced drew 16 Amps!

Hot, discolored wiring near the fuel pump fuse, or occasional blown fuel pump fuses can be an indictor of impending pump failure or problems, too!

NapTownSpeedy · 07-16-2002, 05:46 AM

Warren...Thanks for your reply. So it sounds like I should first look at the Amperage that the pump is pulling. Anything over 8, I should put in a new one. If it is at 8, then I should replace the fuel filter (going to do that this weekend anyway with the regular maintenance). If the noise is still the same after that, then I should just take it as she likes to sing to me!?
Ahh, women and cars. So complex, so rewarding, such a PITA sometimes. Often those little signs are the ones that we miss. They are also the ones that get us in the most trouble. (no offense to any of the female members, I find more often then not it is my foul up not hers [wife/car]

.)