Fuel Pump when Starting the Car


Thread Starter #1
Joined
Apr 17, 2011
Messages
601
Likes
133
Location
Pune
Have anyone of you noticed that when you set the key position to ON (all tell tale lights are on) you hear on the back of you vehicle a sound comes on for about 40-50 secs and then stops. It is the fuel pump.

My concern is not on the sound, is it good enough to crank the engine before the pump stops? as it may be applying a pressure to the intake system for the fuel to be air free. If a premature crank is initiated it may induce air bubbles in the fuel supply. Not sure just a thought came to my mind.

Experts will know more.
 

Varun560061

Honoured Member
Joined
May 1, 2011
Messages
3,588
Likes
727
Location
Bangalore
I think as you said its the fuel pump which makes the noice when the ignition is turned on. Its better we wait for it to finish its job by feeding the fuel to the engine before we start.

If we are starting before the procedure it might apply more pressure on the pump..
Some times, our car's wont start at the first crank, I guess this is of the same reason..
 
Joined
Jun 9, 2011
Messages
90
Likes
3
Location
Cyberspace
No no bubbles, but engine will obviously starve for a few seconds until the fuel is properly pressurized and injected in proper ratio. You are also loading the battery unnecessarily by operating the pump and starter along with ignition at the same time. As a standard practice wait 3 seconds before cranking on any car and idle for 30 seconds before moving off.

Apart from that keep a constant check on the sound. If you suddenly feel a change in sound (speed) it is trying to telling you sumthings gonna go wrong soon.
 
Last edited:
Joined
Jul 18, 2011
Messages
1,973
Likes
324
Location
Melbourne
I am not sure

Try changing it ?

I have a cusco Catch Can that makes this oil pressure sound before I start the car and that too for abt 5 seconds max thats it
 
Joined
Oct 8, 2011
Messages
1,566
Likes
454
Location
Bangalore
Well I hear the fuel pumps sound for max 3 seconds after turning the key to ignition,but hearing a fuel pump powering up for 50 seconds is news to me,which car is this,Ritz diesel or petrol(guessing from profile pic)?
 
Joined
Dec 15, 2011
Messages
2,539
Likes
1,301
Location
M.P.
Yes, the whirrrrrr-click sound that you hear when the ignition is turned on is that of the priming of the fuel pump. It is a good practice to crank the engine only after the 'click' sound is heard.
 
Joined
Dec 24, 2011
Messages
115
Likes
23
Location
Thiruvanathapuram
As soon as you connect external battery the pump would start.

I was referring to a dead battery and jump starting without an external power source.

The sound should last only for very few seconds more or less close to the same time for which heating coil light glows in the instrument cluster. It should not take close to 50 seconds.
 
Joined
Dec 24, 2011
Messages
115
Likes
23
Location
Thiruvanathapuram
Hyundai user manual says that if we do not crank the engine after 10 seconds from the heating coil sign goes off, we have to turn off the key and turn on again so that the heating coil is activated again. We should not give more time to crank the engine after the heating coil goes off
 
Thread Starter #11
Joined
Apr 17, 2011
Messages
601
Likes
133
Location
Pune
I was referring to a dead battery and jump starting without an external power source.

The sound should last only for very few seconds more or less close to the same time for which heating coil light glows in the instrument cluster. It should not take close to 50 seconds.
Ahh u mean "dhakka start?" then i dont know[confused] may be when doing dhakka start the engine gets cranked with the residual amount of fuel left in the lines, dont know and i generally dont see the glow plug light coming on may be for just a split second during cold mornings but not otherwise

Well I hear the fuel pumps sound for max 3 seconds after turning the key to ignition,but hearing a fuel pump powering up for 50 seconds is news to me,which car is this,Ritz diesel or petrol(guessing from profile pic)?
Yeah its a ritz diesel. I guess it takes more time in a diesel to build up the fuel rail pressure(crdi) while such thing don't exists in a petrol.
 
Joined
Dec 9, 2010
Messages
9
Likes
0
Location
Mumbai
You hear the sound of fuel pump running initially because there is no fuel to the inlet side of the pump. As it starts and gets filled up the sound gets muted in the liquid. Pump is always powered when car is running. Pump failure will cause shut down soon.
In most of the cars the tank is located below the height of pump .

There is always fuel in the line for the engine during starting, so push start will also start the car in most of the cars without a charged battery. subsequent starting ensures the alternator powering the fuel pump to keep the feed pressure and flow. pushing also starts the alternator to start building up voltage

In diesel engines with glow plugs you are asked to wait for the plug to heat up good to burn the fuel mixture

Fuel pump noise increase can be associated to clogged fuel filter, which reduced the mass flow rate
 
Thread Starter #13
Joined
Apr 17, 2011
Messages
601
Likes
133
Location
Pune
thanks for the info skoda. Yeah fuel pump runs again after the engine is cranked, the sound does not diminish due to the liquid i think, i can clearly hear a cut-off sound (tak-click) when the pump stops. I was thinking [thinking] to lay down in the boot area and ask my wife to switch on wait and start the car just to hear the pump coming alive again.Could get thrown out of 7th floor for doing this [roll]

Well the whole point is should we wait for the process to complete or just ignore it.
 
Last edited:
Joined
Dec 1, 2011
Messages
42
Likes
1
Location
Mumbai
Hi Guys,

This thread makes an interesting read. I have a few points to make which I think may be pertinent. No Offence meant to anyone , just want all of us to introspect.

1. How can one be sure that the noise heard at the start is the noise of the FUEL pump starting? It can be that of the pre-lub pump (if one is provided) before the cranking takes place to lubricate the bearings, especially the Bottom End.

2. As far as I know, usually there should be no air bubble present in the fuel line after the fuel pump unless the injector is leaking.

In my opinion there is no need for any priming fuel pump to operate before start of the Engine.
 
Joined
Dec 9, 2010
Messages
9
Likes
0
Location
Mumbai
Morning remove the fuel pump fuse and start your car, many things will be clear. Oil pumps are mechanical ones.

Don't know if new cars have got electrical oil pumps.
 
Top Bottom