Fuel pressure
03-06-2018, 06:03 PM
#1
Staging Lane
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Fuel pressure I installed fast fuel rails with the gauge, and when I prime it itll go between 45-55 psi, and after a few hours slowly go down to 0. Is this normal?
03-06-2018, 06:25 PM
#3
Staging Lane
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Cool, i was just wondering because my brother put the same rails and gauge on his 98 camaro and his pressure never drops below 20 ever, and mine goes to 0 after a half day or so
03-06-2018, 06:44 PM
#5
you dont really want pressure in any line when you aren't using it. pressure can wear stuff out. Garden hose wont last long if you keep it fully pressurized all the time. check valves have to deal with that pressure in a fuel pump if they hold it.
Some pumps don't even have check valves. I think walbro 450 has no check, I was told recently because I was tuning my friend's car and I noted how fast it dropped, he said it was normal for the 450. I shrugged. It only really makes a differnce the instant you hit the key, if you do not wait to prime and go right to cranking. Most ECU have a tiny prime delay for key turning also to wait for pressure to build anyways, before trying to inject. In my computer I can change the time it takes. Good if you have huge lines and a big slow pump, like an A1000 on a -10 fuel system seems to take a full second compared to the .150 seconds a stock size pump takes like the stealth.
Some pumps don't even have check valves. I think walbro 450 has no check, I was told recently because I was tuning my friend's car and I noted how fast it dropped, he said it was normal for the 450. I shrugged. It only really makes a differnce the instant you hit the key, if you do not wait to prime and go right to cranking. Most ECU have a tiny prime delay for key turning also to wait for pressure to build anyways, before trying to inject. In my computer I can change the time it takes. Good if you have huge lines and a big slow pump, like an A1000 on a -10 fuel system seems to take a full second compared to the .150 seconds a stock size pump takes like the stealth.
03-06-2018, 06:49 PM
#6
ModSquad
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you dont really want pressure in any line when you aren't using it. pressure can wear stuff out. Garden hose wont last long if you keep it fully pressurized all the time. check valves have to deal with that pressure in a fuel pump if they hold it.
Some pumps don't even have check valves. I think walbro 450 has no check, I was told recently because I was tuning my friend's car and I noted how fast it dropped, he said it was normal for the 450. I shrugged. It only really makes a differnce the instant you hit the key, if you do not wait to prime and go right to cranking. Most ECU have a tiny prime delay for key turning also to wait for pressure to build anyways, before trying to inject. In my computer I can change the time it takes. Good if you have huge lines and a big slow pump, like an A1000 on a -10 fuel system seems to take a full second compared to the .150 seconds a stock size pump takes like the stealth.
Some pumps don't even have check valves. I think walbro 450 has no check, I was told recently because I was tuning my friend's car and I noted how fast it dropped, he said it was normal for the 450. I shrugged. It only really makes a differnce the instant you hit the key, if you do not wait to prime and go right to cranking. Most ECU have a tiny prime delay for key turning also to wait for pressure to build anyways, before trying to inject. In my computer I can change the time it takes. Good if you have huge lines and a big slow pump, like an A1000 on a -10 fuel system seems to take a full second compared to the .150 seconds a stock size pump takes like the stealth.
03-06-2018, 08:46 PM
#7
TECH Senior Member
As long as you have 58-60psi while running, you have nothing to worry about.
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03-07-2018, 11:14 AM
#9
I run 38psi of fuel pressure base usually. Less pressure while running means longer fuel system component life span. That goes for all hydraulic systems; lowering pressure means less stress. Stress is a measurable, mathematical attribute that equals to pressure divided by area. (or force / area if you want)
03-07-2018, 11:55 AM
#10
I run 38psi of fuel pressure base usually. Less pressure while running means longer fuel system component life span. That goes for all hydraulic systems; lowering pressure means less stress. Stress is a measurable, mathematical attribute that equals to pressure divided by area. (or force / area if you want)
And I guess we better get all those cars and trucks with 200k on their stock fuel components off the road before they start leaking fuel everywhere.
03-07-2018, 01:04 PM
#11
TECH Senior Member
Talon, your BS factor just hit a new high.... Spartan7 has it right.
03-07-2018, 01:55 PM
#12
At it again, I see. F=PA, or P=F/A is simply the relationship of force to pressure in a hydraulic system. And it's not a measure of "stress" in that system, it relates to force generated by pressure.
And I guess we better get all those cars and trucks with 200k on their stock fuel components off the road before they start leaking fuel everywhere.
And I guess we better get all those cars and trucks with 200k on their stock fuel components off the road before they start leaking fuel everywhere.
I quoted from the book of mechanical engineering a definition for stress, so also correct.
same equation for axial loading of a piston surface, stress.
gg