Quote:
Originally Posted by stlrj
Even a warm engine without residual pressure should be able to start immediately if the thermo time switch is working properly to engage the cold start valve which is designed to work in a warm engine that has been without residual pressure for over 3 hours.
But to put your mind at ease about residual pressure, you could easily test it without gauges simply by reaching under and pushing up on the sensor plate while feeling for any resistance after 15 mins. If you feel any resistance, you have residual pressure... it's that simple. After 20 min to a half hour all residual pressure is gone and yet your engine should still be capable of starting instantly with the cold start valve, provided the thermal time switch is working.
Cheers,
Joe
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Joe,
You have been claiming the above statement for years and I have to disagree because it not the case. It is about time we address this myth. I just ran a test a few hours ago to demonstrate and explain the discrepancies of your claim. And I have performed this test so many times to evaluate residual pressure loss in a CIS.
Time (min.).......Pressure
initial..................35 psi.
after 20'..............25
after 30'..............24
after 40'..............23
after 50...............22
after 60...............21.5
after 70...............21
after 80...............20.5
after 90...............20
End of test. After more than 90 mins. there was still residual pressure and heavy resistance when you lift the FD plunger up. This is what a normal CIS residual pressure should look like and a zero residual after 30 mins. simply indicates fuel leak in the system. The pressure gauge would drop to zero reading after several hours (3 or longer) and should be able to restart after several days or weeks.
The TTS (thermotime switch) operates no longer than 8 sec. (+/-1) and will automatically shut off. TTS is not operable (off) when the engine temperature is warm (113°F and above). So you could crank a warm engine (113°F plus) and the CSV (cold start valve) will not come into action unless there is an electrical anomaly in the system.
This is the reason why it won't restart when the engine is above 113°F and has loss the residual fuel pressure. Wait a little longer until the engine temperature drops below 113°F and CSV could be operational again.
Tony