Hmmm, OK. And what is the perceived benefit of doing this?
do you prime your fuel pump before you start it
- Thread starter swirlparanoid
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Some (usually older) vehicles leak down pressure in the fuel system. If it does then letting the pump run for a couple seconds before turning to 'start' can make the engine catch quicker.
I start the car normally, and you should too.
The only time I did this is when I had a vehicle with partially plugged fuel injectors that caused a hard starting problem. Not starting until the fuel pump primed for a few seconds made the engine easier to start. Other than that one special case, I just fire up and go.
Originally Posted By: Footpounds
I'm not sure I understand this. The pump is obviously primed when you shut it off. The fuel pump is totally submerged in fuel. So how does the fuel pump LOSE it's prime under those conditions?
In my case, it's due to wanting the fuel system to be purged of air. Air in a diesel-lubed fuel pump means there's metal-to-metal contact. Generating 30k psi injection pressures makes me want to have all the lubrication there as I possibly can.
I'm not sure I understand this. The pump is obviously primed when you shut it off. The fuel pump is totally submerged in fuel. So how does the fuel pump LOSE it's prime under those conditions?
In my case, it's due to wanting the fuel system to be purged of air. Air in a diesel-lubed fuel pump means there's metal-to-metal contact. Generating 30k psi injection pressures makes me want to have all the lubrication there as I possibly can.
Kestas
Staff member
Do you really think air is a significant problem after it's compressed to 30K psi? At that point it's probably in solution.
my cars have a sensor that cuts power to the pumps if it does not "see" the engine turnimg.
Thats true, but most cars have it on a timer, so even if it isnt spinning it will run. Common cutout is about 5 seconds. If you listen closely when you turn it to on you should hear the pump power on for those few seconds.
Originally Posted By: Kestas
Do you really think air is a significant problem after it's compressed to 30K psi? At that point it's probably in solution.
Not entirely sure, to be honest, but I'd rather be safer than as sorry.
Do you really think air is a significant problem after it's compressed to 30K psi? At that point it's probably in solution.
Not entirely sure, to be honest, but I'd rather be safer than as sorry.
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