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Mark R Steitle wrote:
Jim,
I went back to the article (http://www.autoshop101.com/forms/h42.pdf) and looked at the drawing on pg. 5. I noticed two things I had missed at first, the pressure regulator is in the tank with the pump and filter, which seems to go against the advice to put the pressure regulator at the end of the system. And the jet pump appears to be connected to the return line of the pressure regulator. Tracy stated that adding such a device to the return would mess up the fuel pressure readings. He should know. I would still like to experiment with this gizmo at a future date… once I get caught up on all the other stuff around the house. Interesting mental exercise none the less.
Mark S.
I'm still wondering how important that pressure is.
First, didn't we learn earlier that the flow doesn't vary linearly with the pressure differential; that it take a lot more pressure to get a significant difference in flow? This would tend to limit the effect of MAP changes. Referencing somewhere other than MAP will make a difference, just not a whole lot. Would this be a reason that all of the returnless systems are running at higher pressures? Say the MAP varies 15", there's less percentage difference between 30"->45" than there is 45"->60". That keeps you in the ballpark. The ECM takes up the rest of the slack.
Then there is the fact that Ed has flown at least a couple hours with a system that was not referenced to MAP. The original problems were tuned out.
Leon, I'm not claiming to know anything. Shoot, I'm still a month away from STARTING my first engine rebuild. But it just seems to me that with an atmospheric controlled regulator, all that you would need would be a throttle position sensor to know how much fuel to dump in the intake. The regulator will relax the pressure as you climb to lean the mixture. And except for barometric difference, the MAP will always be tied to the throttle position. Now all you need is a fuel map that says how much fuel to use at each throttle position. I'm sure I'm missing something, and I'm sure it's not the sort of thing you find in textbooks.
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