Need some help MASFLOEFI
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Joined: Mar 2008
Posts: 98
Likes: 21
From: San Mateo Ca
Actually, there are two items that need to be verified:
1) What is the current fuel rail/regulator pressure with the vacuum port disconnected? This should be 40 psi according to the info from MassFlow EFI. (BTW, since your injectors are rated at 37 LB/HR at 43.5 psi, they will flow roughly 35.45 LB/HR at 40 psi which is closer to the calculated 34.57 LB/HR needed for 440 HP.)
The Regulator was set to 40lbs w/ vacuum disconnected initially
2) Does the vacuum port work by lowing the fuel rail/regulator pressure when the engine is running. Need to check two things - ensure the port receives an engine vacuum signal at idle and that the vacuum signal is strong enough to allow the regulator to reduce the fuel pressure below 40 psi.
Vacuum is at 15lbs at idle
I think that item #2 is the critical pass/fail item. You can always reset the fuel pressure to a lower than recommended 40 psi to get the engine at least running; however, to have a streetable ride, the vacuum compensator must be working properly. I would trace the source of the engine vacuum to make sure the vacuum reading that you see at the source is the same that you see at the regulator.
Again, over the years I've seen all sorts of problems come into the shop from split hoses to check-valves installed backwards. Perhaps the most common mistake I've seen on carburetored Vettes is using ported vacuum (above the throttle blades) used instead of engine vacuum (below the throttle blades). Good luck!
1) What is the current fuel rail/regulator pressure with the vacuum port disconnected? This should be 40 psi according to the info from MassFlow EFI. (BTW, since your injectors are rated at 37 LB/HR at 43.5 psi, they will flow roughly 35.45 LB/HR at 40 psi which is closer to the calculated 34.57 LB/HR needed for 440 HP.)
The Regulator was set to 40lbs w/ vacuum disconnected initially
2) Does the vacuum port work by lowing the fuel rail/regulator pressure when the engine is running. Need to check two things - ensure the port receives an engine vacuum signal at idle and that the vacuum signal is strong enough to allow the regulator to reduce the fuel pressure below 40 psi.
Vacuum is at 15lbs at idle
I think that item #2 is the critical pass/fail item. You can always reset the fuel pressure to a lower than recommended 40 psi to get the engine at least running; however, to have a streetable ride, the vacuum compensator must be working properly. I would trace the source of the engine vacuum to make sure the vacuum reading that you see at the source is the same that you see at the regulator.
Again, over the years I've seen all sorts of problems come into the shop from split hoses to check-valves installed backwards. Perhaps the most common mistake I've seen on carburetored Vettes is using ported vacuum (above the throttle blades) used instead of engine vacuum (below the throttle blades). Good luck!
At 40lbs regulator pressure the engine will barely stay running. I person cannot physically stay in the garage very long due to the extremly rich exhaust fumes, that is with the garage door open and a fan blowing out. Fuel consumption has been approx. 6 gallons with only a couple miles driven around the block.
I checked the pressure pre rail and found something odd, I think. I started engine with the regulator open, zero on both gauges. I increased the regulator pressure to approx. 15 lbs, the rail pressure started to increase slowly until it maxed out at about 30 lbs. Engine RPM was between 1000 to 2000rpm. Shouldn't this gauge have read 15lbs same as regulator?
Burning Brakes
Joined: Jan 2003
Posts: 755
Likes: 32
From: Roswell Georgia
All hoses are new and checked. The vacuum port I am using is the port shown on the Massflo set up.
At 40lbs regulator pressure the engine will barely stay running. I person cannot physically stay in the garage very long due to the extremly rich exhaust fumes, that is with the garage door open and a fan blowing out. Fuel consumption has been approx. 6 gallons with only a couple miles driven around the block.
At 40lbs regulator pressure the engine will barely stay running. I person cannot physically stay in the garage very long due to the extremly rich exhaust fumes, that is with the garage door open and a fan blowing out. Fuel consumption has been approx. 6 gallons with only a couple miles driven around the block.
The 40 psi figure is for WOT operation only, i.e., zero engine vacuum. That's why the engine is running so rich when the fuel pressure regulator is set to this value with the vacuum compensator port disconnected. Once this value has been set, reconnect the vacuum compensator port and the fuel pressure should drop immediately ending the super-rich condition.
I checked the pressure pre rail and found something odd, I think. I started engine with the regulator open, zero on both gauges. I increased the regulator pressure to approx. 15 lbs, the rail pressure started to increase slowly until it maxed out at about 30 lbs. Engine RPM was between 1000 to 2000rpm. Shouldn't this gauge have read 15lbs same as regulator?
