Sound of fuel pump cycling on start-up

O

Old-Duckman

Active member
 SW Pennsylvania USA
Usually when I turn the ignition key to the 2nd position prior to turning over the engine I hear a series of short sounds that I assume is the fuel pump cycling. Sort of short noises about 5 in a row and then I start the engine.

Today I did the same thing but got a single steady groaning sound, when it stopped I started the car and it idled fine. I pulled the car out of the garage to go for a ride and it started to rain, really didn't want to get the car dirty so I shut off the car, opened the garage and when I started the car to pull it into the garage I got the groaning sound again. Just went out to the garage (been about an hour) and it made the groaning sound again.

So my question is, is this a sign of something going wrong or..?
If it is no big deal, then why is it sounding differently than it has before ?
 
Mister T said:
Could well be that the fuel pump is on the way out. Or it just be that the battery voltage is a bit low.
Click to expand...
Just checked battery voltage, it is 12.4. Checked it at the posts inside the engine compartment not at the actual battery.
 
they do get noisy as they age especially when fuel is low in the tank, a full tank of shell super with some cleaner additive run through may help in the short term
 
That sounds as said like fuel pump on its way out as mine was doing the same last September I could feel the vibration through the seat so I got a new one fitted the day I took the car in to be fixed the idle had got really bad was relieved to make it to the garage.
 
Did a lot of research on the web last night re: proper battery voltage (hoping it was just the battery). One site said 12.4 was ideal, most others said it is weak, on its way out.

Just got back from the garage and checked voltage at the battery this time instead of at the points in the engine compartment. The positive terminal clamp was so loose I could have pulled it off without any loosening of the nut. I tightened it up and will take the car out for a drive when I get a chance and see if that makes a difference.

The battery looks rather new but no markings as to its age. Most batteries have a sticker showing when they were installed. Oh well, hoping that was the problem...I’ll post again one way or the other once I’ve taken a long ride to charge up the battery.
 
When I had a 3.0 e85 ,the fuel pump started to be noisy on start up .I put 125 ml of Redex petrol cleaner in the tank (this was half the bottle) this cured the problem.
 
maxman said:
When I had a 3.0 e85 ,the fuel pump started to be noisy on start up .I put 125 ml of Redex petrol cleaner in the tank (this was half the bottle) this cured the problem.
Click to expand...
Well I’ve got a can of “ Sea-foam” and “ Liqui Moly Gasoline”. Can’t hurt using one or the other at my next fill up but I want to see if the loose clamp was the issue first. I try to do one thing at a time so I can narrow down the problem. If I do two things at the same time I won’t know which one worked...I just hope one of them does.
 
Been doing some Net searching on this topic and found this on Bimmerfest:
https://www.bimmerfest.com/forums/showthread.php?t=377057

Basically this owner was told by a BMW service manager:
"drive the gas down below 1/4 tank, then fill it all the way up, then drive it at least 50 miles."
The owner said it worked and the "roar" (as he described the sound) "never came back".

I'm going to try it and will post the results. It will take awhile to get that many miles, I have a bit over 100 miles on this tank so to get below 1/4 tank will take some driving and then over 50 miles on the next fill-up. What with all the lock downs, I can drive all I want but not much is open to have a place to go to...Guess I'll just do some exploring.
 
Well about 3 days on a BatteryMINDer in the "de-sulfate" mode and the sound is back to normal. I'm not going to do the run it down to a 1/4 tank thing as apparently it was a weak sulfated battery. Great thing that BatteryMINDer !
 
Make sure the tank never drops below a quarter to ensure longevity in the fuel pump.
 
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