Fuel Pressure
- Thread starter Jayhall
- Start date
base fuel pressure should be 40psi with the vacuum line detached and pinched or plugged. the base fuel pressure setting should come from the atmosphere. when you put the vacuum line back on, it should drop to around 32psi or so... (it varies depending on how healthy your engine is. 
)
-shaeff
)-shaeff
" it varies depending on how healthy your engine is. "
wow, never herd that before, would it go down more or less if your engine was healther? How does this work exactly?
wow, never herd that before, would it go down more or less if your engine was healther? How does this work exactly?
well, a very healthy engine will have better vacuum then a 200k mile engine, or simply one that's been beat to hell it's whole life... which is why toyota gives a range of specified fuel pressures, rather then just one number. it'll vary over time. what does your car pull in vacuum? mine pulls ~21. that's nice and healthy. others only pull ~18 or 19. so it wouldnt drop the fuel pressure quite as much.
i'm not sure if the FPU VSV is supposed to control this or not. i think that it only works when you're in positive pressure, so that you dont run rich when in vacuum. i'm not exactly sure, but i guess i'll look into it, as now i'd like to know, too.
-shaeff
i'm not sure if the FPU VSV is supposed to control this or not. i think that it only works when you're in positive pressure, so that you dont run rich when in vacuum. i'm not exactly sure, but i guess i'll look into it, as now i'd like to know, too.
-shaeff
Two good posts shaeff.
The FPU VSV is active only during hot starts. The ECU samples the coolant sensor and opens the FPR vacuum port to atmosphere for 60-90 seconds after starting This increases the fuel pressure to clear any vapor and helps in a smooth idle for a few minutes. After appx 60-90 seconds the FPR port is reconnected to the intake manifold.
The FPU VSV is active only during hot starts. The ECU samples the coolant sensor and opens the FPR vacuum port to atmosphere for 60-90 seconds after starting This increases the fuel pressure to clear any vapor and helps in a smooth idle for a few minutes. After appx 60-90 seconds the FPR port is reconnected to the intake manifold.