Fuel Starvation
Discussion
Hi, Anyone with a knowledge of Carb'd V8's out there? I'm running a Sierra with a 302V8 which when the tank get to half full loses fuel pressure and won't rev to anything over 4500rpm or stalls, also can happen when throwing around a track in tight corners. I spun it on a track the other day and the car cut out once it had come to a standstill. I've checked the fuel gauge is reading OK, I've recently put on a new Holley fuel pump, pressure regulator, and had the Holley carb rebuilt professionally. As I say full tank of fuel and the wee beastie revs it nuts off shows 5-6psi on the inline gauge, half a tank, stalls and 0psi. Any ideas?
Assume it isn't as simple as fuel surge in the tank exposing the outlet to air? You don't say what sort of pump you have, but some of them seem very bad indeed at coping with restriction on the supply side - they can blow but not suck if you see what I mean. Possibly just the extra head of fuel in the tank gives enough pressure at the pump inlet for it to work? If you can get the problem to occur stationary you may be able to show what's going on by looking at the pressure between the pump and the tank. A simple manometer teed in should be enough.
More info please.
Where in the tank does the fuel pick up? What is the design of the pick-up pipe? Ideally this would be low down in the side with a pipe passing into the tank and bending down to point at the floor of the tank.
Where is the pump positioned? Again this should be as low as possible because, as has been said, they don't like to suck.
If this happens any time the tank level is low then surge is not the issue and a swirl pot will not fix it.
My money is on pump position.
Steve
Where in the tank does the fuel pick up? What is the design of the pick-up pipe? Ideally this would be low down in the side with a pipe passing into the tank and bending down to point at the floor of the tank.
Where is the pump positioned? Again this should be as low as possible because, as has been said, they don't like to suck.
If this happens any time the tank level is low then surge is not the issue and a swirl pot will not fix it.
My money is on pump position.
Steve
Have the fuel lines been increased in size? is it still the standard tank? And as said pump location and type.
EDIT:- just read your profile, this is a standard car from South Africa isnt it? Ive only ever seen one XR8, get some piccys up
EDIT:- just read your profile, this is a standard car from South Africa isnt it? Ive only ever seen one XR8, get some piccys up
Edited by Mikey G on Saturday 13th January 08:39
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