Fuel Pressure Q
Discussion
LS7 - Up until yesterday the engine has been firing on first start.
Then yesterday it would not start.
On ign I noticed that the fuel pumps start fine, the HP pump priming the injector circuit as normal (start - stop) and the pressure reg shows 60 as normal....but unlike previous times where the 60 psi remains rock-solid, now the pressure drops to around 30 pretty-much within a second or two.
Tanks full
Oh and can someone tell me what the whistling sound is (crank or run for a bit - than shut off and ...whistle!
cheers
Keith
Then yesterday it would not start.
On ign I noticed that the fuel pumps start fine, the HP pump priming the injector circuit as normal (start - stop) and the pressure reg shows 60 as normal....but unlike previous times where the 60 psi remains rock-solid, now the pressure drops to around 30 pretty-much within a second or two.
Tanks full
Oh and can someone tell me what the whistling sound is (crank or run for a bit - than shut off and ...whistle!
cheers
Keith
V8 Vum said:
LS7 - Up until yesterday the engine has been firing on first start.
Then yesterday it would not start.
On ign I noticed that the fuel pumps start fine, the HP pump priming the injector circuit as normal (start - stop) and the pressure reg shows 60 as normal....but unlike previous times where the 60 psi remains rock-solid, now the pressure drops to around 30 pretty-much within a second or two.
Tanks full
Oh and can someone tell me what the whistling sound is (crank or run for a bit - than shut off and ...whistle!
cheers
Keith
If it always held pressure and now it doesn't that would only be either your pressure reg not closing off completely or depending on how your fuel system is done a check valve on a pump stuck open. Either that or check for a fuel leak you haven't noticed. Then yesterday it would not start.
On ign I noticed that the fuel pumps start fine, the HP pump priming the injector circuit as normal (start - stop) and the pressure reg shows 60 as normal....but unlike previous times where the 60 psi remains rock-solid, now the pressure drops to around 30 pretty-much within a second or two.
Tanks full
Oh and can someone tell me what the whistling sound is (crank or run for a bit - than shut off and ...whistle!
cheers
Keith
02PRUV said:
If it always held pressure and now it doesn't that would only be either your pressure reg not closing off completely or depending on how your fuel system is done a check valve on a pump stuck open. Either that or check for a fuel leak you haven't noticed.
That's pretty-much my thoughts - It did hold pressure before, and there is no leak. Anyone know how these regulators should behave?How to diag this I don't know, so it may have to wait for someone else to do when I am closer to the end of the build.
Who else has a whistling LS7 (on turn-off), sounding like a deflating air-mattress - and where is the sound coming from (front of the engine somewhere)? Just curious!
V8 Vum said:
That's pretty-much my thoughts - It did hold pressure before, and there is no leak. Anyone know how these regulators should behave?
How to diag this I don't know, so it may have to wait for someone else to do when I am closer to the end of the build.
Who else has a whistling LS7 (on turn-off), sounding like a deflating air-mattress - and where is the sound coming from (front of the engine somewhere)? Just curious!
My old LS2 did the whistling. Kyle said it was OK but I can't remember what he said it was though (grey cells are diminishing rapidly these days). How to diag this I don't know, so it may have to wait for someone else to do when I am closer to the end of the build.
Who else has a whistling LS7 (on turn-off), sounding like a deflating air-mattress - and where is the sound coming from (front of the engine somewhere)? Just curious!
Paul
depending on the amount of vaccum your oil pumps are generating you are hearing the air that is sucked
back in the crankcase. Depending on the setup - it could suck it through the air inlet if you have your
rocker cover vent hoses connected there.
In my case it sucks the air back from the vent of the oil tank through a small breather tank
with a filter. It is quite loud.
back in the crankcase. Depending on the setup - it could suck it through the air inlet if you have your
rocker cover vent hoses connected there.
In my case it sucks the air back from the vent of the oil tank through a small breather tank
with a filter. It is quite loud.
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