Fuel pressure bleed down time
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From: Kannapolis, NC
Fuel pressure bleed down time I will try to post this question here since I cannot get the answer in another section. Trying to figure out some tuning stuff wanted to make sure this was normal never took notice to it before.
Search is not working. What is the the fuel pressure bleed time allowment? When I turn my key on it goes up to 59-60 and then when the pump stops running it drops to around 45ish and will continue to bleed down after a couple of minutes. L76 injectors and 255lph Walbro in tank pump. Thanks guys.
Search is not working. What is the the fuel pressure bleed time allowment? When I turn my key on it goes up to 59-60 and then when the pump stops running it drops to around 45ish and will continue to bleed down after a couple of minutes. L76 injectors and 255lph Walbro in tank pump. Thanks guys.
I don't know if there's a golden rule but I check for bleed down when I'm diagnosing fuel problems. I generally look for at least 2-5 minutes pressure maintenance. If it's starts falling soon after the car is shut off then it could be pressure regulator,one way check valve in the fuel pump,fuel injector,or leak in the fuel system lines.
from my 2002 gm service manual, page 6-1643, step #4 in diagnosis,
"important: fuel pressure may vary slightly when pump stops running but should stabilize and remain constant." It says monitor pressure for 1 minute after it shuts off and gives a 5 psi drop as acceptable.
If pressure do NOT drop more than 5 psi, then goto step #5 if which is to relieve fuel pressure down to 10psi and monitor for 1 minute, if it drops more than 2 psi (to less than 8 psi gauge) then replace the fuel pump;
or if pressure DOES drop more than 5 psi then it talks about using special tool on fuel rail and removing rail to find the leaky injector.
There are quite a few different steps in the diagnosis, but all use a time of 1 minute for monitoring fuel pressure. hope that helps.
"important: fuel pressure may vary slightly when pump stops running but should stabilize and remain constant." It says monitor pressure for 1 minute after it shuts off and gives a 5 psi drop as acceptable.
If pressure do NOT drop more than 5 psi, then goto step #5 if which is to relieve fuel pressure down to 10psi and monitor for 1 minute, if it drops more than 2 psi (to less than 8 psi gauge) then replace the fuel pump;
or if pressure DOES drop more than 5 psi then it talks about using special tool on fuel rail and removing rail to find the leaky injector.
There are quite a few different steps in the diagnosis, but all use a time of 1 minute for monitoring fuel pressure. hope that helps.
Walbros are notorious for bleeding fuel pressure, as well as other problems that people inexplicably seem to just put up with. BTW, this should be in the fueling section, not advanced. Maybe someday I will hear a reasonable explanation for why people like those infernal POS pumps, but I haven't yet.
The fuel pump chack valve is not there to keep fuel system pressure up as to keep the fuel from draining back into the tank. Unless you are having a hard time starying the engine I would not worry about it.
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Busa,mine does the exact same thing.Turn key to start......62 psi,turn key off and it lowers to 45 ish.No problems at all with starting or anything else so I don't worry about it.Traver
