Quote:
Originally Posted by ABDow
Just to update on my hot start problem. I found that the fuel pressure was 33 PSi - above the recommended tolerance - and wound it back to 28 PSI. My hot start problem has vanished. Not sure of the reason, unless higher pressure makes the fuel more likely to vaporise. Intuitively I would have thought the opposite - that the boiling point would be higher under pressure.
Alastair
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At higher pressures, gasoline will be less likely to vaporize. Generally, increasing pressure will help.
The D-Jet fuel pumps have an internal relief valve that recycles fuel back to the pump suction if the downstream pressure is too high. I have know idea of what the original set pressure was, but perhaps higher pressure causes more recycle leakage?
It would be interesting to test the fuel flow from the fuel pressure regulator at different pressures. Being a positive displacement pump, there should be little change. But if fuel flow drops, that could explain why vapor locking occurs.
Only other possibility I can think of, is that higher pressure causes pump to draw more current. If there are bad connections, a voltage drop could occur. The pump output is strongly affected by voltage.