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My 1997 C5 fuel pump whines in hot weather and the whining fluctuates to the beat of my turn signal flasher and changes tones when I apply the brakes. I'm on my fourth fuel pump and I also replaced the right tank jet pump, the right tank pressure relief valve, the EVAP purge valve and the EVAP switch valve. I also replaced the fuel pump relay. I have not replaced the EVAP cannister. In colder weather, I can drive for 100 miles with no fuel pump whine but as soon as the outside temp goes above 75 to 80, the fuel pump whines after 15 to 25 miles of driving. Anybody know of anybody else that had this issue and if they discovered what causes it?
My 1997 C5 fuel pump whines in hot weather and the whining fluctuates to the beat of my turn signal flasher and changes tones when I apply the brakes. I'm on my fourth fuel pump and I also replaced the right tank jet pump, the right tank pressure relief valve, the EVAP purge valve and the EVAP switch valve. I also replaced the fuel pump relay. I have not replaced the EVAP cannister. In colder weather, I can drive for 100 miles with no fuel pump whine but as soon as the outside temp goes above 75 to 80, the fuel pump whines after 15 to 25 miles of driving. Anybody know of anybody else that had this issue and if they discovered what causes it?
Summer 2010 after driving into Phoenix from out in the outer suburbs for about one hour in probably 115-120 F weather with bad traffic on freeways going slow, at a red light I heard that noise.
Whine sound that changed in pitch when turn signal on, sounded like the sound effect of the 1960’s Star Trek space ship.
Got out of car and left it running and it was from driver’s side tank.
Went back home in bad freeway traffic got off freeway on my road and engine started stumbling, just barely rolled into a Chevron gas station.
Gas tank wasn’t showing empty.
Put gas in it and drove home, still made that sound.
Tried Techron concentrate plus and it’s not done it again, still on factory pump, jet pump, fuel filter that I am aware, or let’s say the same stuff since April 2003 when I bought the car with 38,000 miles, now at 96,000.
I think there was a chunk of something clogging the jet pump, same crud that made the fuel sender read incorrectly.
Try some Techron concentrate plus, couldn’t hurt.
Run a few treatments through or at least 2, if it doesn’t fix it, still not wasting $$ to clean the intake valves and fuel injectors, etc.
My 1997 C5 fuel pump whines in hot weather and the whining fluctuates to the beat of my turn signal flasher and changes tones when I apply the brakes. I'm on my fourth fuel pump and I also replaced the right tank jet pump, the right tank pressure relief valve, the EVAP purge valve and the EVAP switch valve. I also replaced the fuel pump relay. I have not replaced the EVAP cannister. In colder weather, I can drive for 100 miles with no fuel pump whine but as soon as the outside temp goes above 75 to 80, the fuel pump whines after 15 to 25 miles of driving. Anybody know of anybody else that had this issue and if they discovered what causes it?
Check the voltage supply and ground at the pump with the pump running and the symptom present. Put the meter negative lead on the battery negative post.
I agree that if you haven't you should change your fuel filter. A failing pump can send debris to the filter. I always change them as a pair.
With the car idling and the symptom present, what happens if you remove the gas cap?
Last edited by vito02; Mar 19, 2026 at 08:09 PM.
Reason: Addition
If you are on your 4th fuel pump it's not the fuel pump...I'm 99% sure the fuel pump ground which is G401 is shared with your rear turn signal bulbs so that is why you are hearing the whining fluctuate with the turn signal...I would test G401 which is on the left rear frame rail inboard of the left rear tire.
I had this same problem on my 98 on a trip from San Diego to Phoenix. It was over 100 degrees.
Noise sounded like an air-raid siren - very loud... and it pulsed with the turn signal.
I also smelled gas.. so I assumed the pump was dying.
I had a shop install a new fuel pump and was able to drive the car home... but THE NOISE RETURNED about 1/2 way home!
Since then I have cleaned the ground point in the rear wheel well - both the fuel pump and rear lights share this ground. It was mostly painted over with black chassis paint.
I'm also going to change the fuel filter as it's been over 50K miles.
We haven't had any hot days yet.. so I can't say if this problem is fixed.
I did decide to change the fuel filter.. I cut the old one open.. It looks a little gritty.. Possibly clogged?
All grounds found and cleaned. Fuel pump still whines after long drives on hot days. I'm wondering if it has anything to do with altitude. I'm at about 4650' above sea level.
First of all, I'd put the electrical problem to bed. There shouldn't be a significant dip in the 12 vDC "bus" voltage. Use a volt meter. When the turn signal/brake lights first flash on, you should see, at most, a quick dip and recovery of bus voltage.Ideally this dip, a downward spike, should be so fast you don't see it on a hand held volt meter. As suggested, make sure the grounds have no resistance; bare metal to bare metal connector.
Second suggestion is probably too much of a science project....rig up a fuel pump so that the pump sees a normal input and output of fuel. Does it still whine when you power it on.? I have a power supply with a variable voltage output. I'd run the pump at voltages ranging from 12.0 vDC to 14.5 vDC to check out the noise situation.
Apologies for not being much of a help. Interesting problem for sure.
All grounds found and cleaned. Fuel pump still whines after long drives on hot days. I'm wondering if it has anything to do with altitude. I'm at about 4650' above sea level.
I am at sea level and having the same issue!
Also, removing gas cap when noise is present has no effect. It's not pressure or vacuum in the tank causing it.
Fuel pump whine in hot weather
