> Something in the back of my head
> wants to say
> the Carters also don't like "no flow" conditions and are best used with a
> bleed line back to the tank, but I could be thinking of something else.
After looking up the P4070 (which is a rotary vane type rated 72 gph, only
1.2 gpm), I'll bet this is the problem. Rotary vane pumps run continuously,
and put a fair amount of heat into the fuel. Without a minimal flow, the
fuel trapped in the pump can get very warm, which can allow it to vaporize
and make the pump cavitate, making the output pressure go to nearly zero.
When adequate flow is resumed, the fuel doesn't get as warm in the pump, and
the problem doesn't occur. When you're cruising, and the pump is bathed in
all the heat coming back from the engine, things get too warm inside and the
fuel pressure drops.
My suggestion is to either switch to a Facet-type pump, or add a return line
to the tank.
Randall
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