As I'm still suffering with fuelling issues, I posted on the Maestro Turbo FB page looking for some help and guidance. Lee and Dan came back with some suggestions, but what I'm really struggling with is an understanding of how the Turbo fuel system works. Using the diagram below, taken from a Haynes manual, I can see that the fuel is pumped directly from the tank to one side of the vapour separator. Once that fills the fuel is sent to the float chamber through the top outlet. Once that fills, any excess fuel is returned to the tank via the third vapour separator outlet and the pressure regulator to the spill return pipe and the fuel tank. However once the turbo starts to apply boost pressure, this is seen on the pipe from the plenum chamber and applies the pressure to the top of the diaphragm in the pressure regulator, which in turn is applying pressure on the line into the vapour seperator that the fuel normally returns along. Now there is an increae in pressure to force the fuel into the float chamber and limit the fuel being returned to the tank. Am I correct in that description so far?
Thats then brings me to me problem with the mixture going excessively lean as soon as the turbo starts to apply boost. Could it be that the fuel pump is just not good enough to overcome the boost pressure, so I end up in just sending a dribble of petrol and boosted air to the float chamber? As far as I am aware the tank is good, and there are no problems with the gauze or swirl pot, the pressure regulator is brand new as is the carb balance pipe, the pump is Ok and pumps at a reasonable rate (when using it to drain the tank), the vent valve is working when igntion is switched on and off, although I will test with the valve being replaced by a bolt. With the vapour separator being non-serviceable, should I look to change it, even though it looks OK, in case something is wrong internally? Other than these, I'm at a loss to understand why it only goes lean with the turbo on boost. The car drives fine as long as I don't exceed 2000-2500 rpm, and if I do, then letting the engine return to idle speed for a few seconds, brings everything back to running fine. The mixture is about 4%CO at idle at the moment.
Thats then brings me to me problem with the mixture going excessively lean as soon as the turbo starts to apply boost. Could it be that the fuel pump is just not good enough to overcome the boost pressure, so I end up in just sending a dribble of petrol and boosted air to the float chamber? As far as I am aware the tank is good, and there are no problems with the gauze or swirl pot, the pressure regulator is brand new as is the carb balance pipe, the pump is Ok and pumps at a reasonable rate (when using it to drain the tank), the vent valve is working when igntion is switched on and off, although I will test with the valve being replaced by a bolt. With the vapour separator being non-serviceable, should I look to change it, even though it looks OK, in case something is wrong internally? Other than these, I'm at a loss to understand why it only goes lean with the turbo on boost. The car drives fine as long as I don't exceed 2000-2500 rpm, and if I do, then letting the engine return to idle speed for a few seconds, brings everything back to running fine. The mixture is about 4%CO at idle at the moment.
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