Quote:
Originally Posted by OM616
At that pressure with the stock pump spring, how much by pass fuel are you seeing?
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You are right, the overflow volume decreases a little bit, but not that much.
Tested with my old untouched presupply pump with 130k miles on it I had like 10%less overflow volume.
Or to give an example. This August I had some fuel with ~50% gasoline in my car.
After I went shopping (I drove the car for 1hour before) the car would not start when I wanted to leave after 20min shopping because of vapor bubbles in the fuel system.
1. cranking 2 seconds long - nothing happened
2. cranking - after 5 seconds I already heard a few cylinders reporting for duty and stopped
I did wait 5 seconds
3. cranking - after 5 more seconds the engine ran, not nice, but it ran.
And after hitting the gas once the idle was normal.
What I want to illustrate with the example, the overflow volume is still quite sufficient. Even with the wrong fuel.
Quote:
Originally Posted by OM616
....I installed a stronger pump spring in my pumps and am running 30/36 psi with a good amount of bypass fuel.
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Be careful with stronger springs. Too strong springs in the presupply pump can cause bad engine behaviour.
Diesel fuel canīt be compressed and so it does not store any pressure. The spring in the presupply pump can store the pressure so to say.
If the spring in the presupply pump is too strong the pump stroke is finished earlier through the bigger spring force, but the time until the pump-cam loads the spring again is too long then. In that case the oscillating pressure can cause uneven fuel loading of the elements.
I donīt say it will, but it can.
Gruß
Volker