A small correction : the TR3 mechanical fuel pump (like most mechanical
pumps) does not have a separate pressure release valve, but is instead
designed so it simply quits pumping when the fuel pressure rises to the
limit. The linkage pulls the diaphragm down, which draws fuel into the
chamber, but there is only a relatively weak spring to force the fuel
from the chamber into the outlet. The spring only exerts 3-4 psi
pressure on the diaphragm, so the fuel pressure at the outlet cannot be
any higher than that.
I feel Brian Schlorff's explanation is likely to be correct, although
the percolation could be happening anywhere between the front carb and
the fuel pump.
Randall
Bob Labuz wrote:
>
> I am not a TR6 expert, but could there be a problem with your fuel pump? On
> TR3's, the mechanical pump has a pressure release valve to disable the pump
> action when optimum fuel pressure is reached. I have never experienced your
> problem in over 30+ years of TR3 and 4 ownership. I have experienced fuel
> starvation due to stuck valves in both the floats and fuel pump, but never too
> much pressure. Again, I would check the fuel pump. Good luck!!
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