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YOUR RESEARCHFuel pump question
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fuel pump
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Suspected cause · Original poster
After some research I found that it is most likely the fuel pump.
Leading evidence: 'fuel pump' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, the most frequently mentioned possible cause is 'fuel pump' (1 discussions; 0 report identifying it and 1 suggest it). The most frequently discussed action is 'Check smog pump and see if' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Suggestion · Original poster
I'll have to check the smog pump and see if that's it....
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Suggestion · Original poster
My question is, should it be running continuously?
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So I had noticed an audible hum when I put my key in the ignition (but before starting the car). After some research I found that it is most likely the fuel pump. My question is, should it be running continuously? ie, while I was working on the interior of my car for 20-30 minutes, I could hear it the entire time as a quiet high pitched hum/whine.
Is it time to replace it, is there something else going on, or is this normal?
Did you have the key turned at all or do you have it simply slid into the ignition switch?
When you turn the key, I think the SAI pump kicks on. But, this does not happen if the key is just slid into the ignition cylinder.
No, fuel pump runs at most a couple of seconds to prime when engine is not running. The SAI pump sounds like a small vacuum next to the coolant tank and it kicks in only when engine is running.
Is the hum coming from the brake booster/battery area?
I just turned the key to the ignition position on my C4 and listened for the sound that I was remembering. Indeed it was not the SAI fan, but instead a high pitched noise almost a whine that continued until I turned the key off. The noise was not very loud and one might not notice it or be able to hear it unless the car was in a quiet place like a garage. About 30 seconds after I turned the ignition on, there was another noise like a valve moving for a few seconds too. We would have to see a schematic of the ignition/starting operation to see what this might be.
^^^^ This is exactly what I hear. I can't really place it either, walking all around the car trying to pinpoint it. seems to be the loudest when I put my ear up to the center console vents, but it doesn't seem to be in the HVAC system.
I also have a C4 - 2002 cab.
With a durametric you can manually switch a lot of things like the sai pump on and off. Might help you identify what it is. I know my care makes all sorts of electronic whirrs and buzzes when I first switch it on before starting the motor.
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