fuel pump hum

[algae]

firstly, I apologize for posting something so well covered before, but can someone tell me why my pump would have such a low pitch sound? It's very loud and would be about a 60hz freq.(a guess but I hope you get the idea). It's been like that as long as I've owned it(6 years,12,000 miles-75,000 total).Throttle response off idle is poor, not like a 3.4 GM for example,and lately the exhaust is very sooty @ the tips. I tried checking the pressure at the rail 2 yrs. ago and it was over 30, but would have liked to try it under load to see if it would hold up but was unable to. Should I think about replacing the pump????
thanks

 

[NotSoSlowSHO]

Have you pulled any EEC codes?

How many miles are on the car?

 

[algae]

about 75,000 miles, my son has the car right now in another town so I only see it on weekends and haven't checked the codes. There have never been codes in the past, even when one O2 sensor was no good.

 

[jessemachone]

I've got sooty exhaust too! What's the deal? The car still gets about 23 mpg on the highway... I haven't poked around it too much because if it isn't broken, why fix it?

 

[Rockledge]

I'd do a fuel pressure check first, if FP specs are OK, then I would leave the pump alone.

FWIW, I can hear the low pitch hum of my SHO's 1-year old pump just as clearly as I heard the old pump. If you change the pump don't forget the fuel filter, when's the last time it was changed, BTW?

Regarding poor throttle repsonse, you might want to clean the MAF sensor, if even just to rule it out. If the plugs and wires are original, I would start thinking about changing them out. You can check for oil/water/dirt in the plug wells when replacing the plugs. Maybe pop in a new air filter, clean off the ACT sensor while your poking around in the air filter box.

And I'd check the codes again.