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autobonrun's Avatar
 
Join Date: May 2001
Location: Kansas
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Question Fuel System Optimization Question

A while back, I discovered that pressing my accelerator pedal to the floor was not causing the linkage to go to full throttle. An adjustment in the engine compartment fixed this problem and added more acceleration. I'd like to look at other aspects of fuel delivery as well.

What in the fuel system (other than the filter) can cause loss of flow and consequently less than optimum performance? I would think optimizing what you already have would be a better way to gain power than immediately looking at after market additions.

What is the correct variable to measure in the fuel system? My instinct says flow rather than pressure but my instinct may not be correct. I'm sure Porsche provides specs for the pressure but does it provide specs for the flow rate?

Over time, with wear, can a fuel pump lose flow pumping capability even though the system shows the correct pressure, or can this combination not happen?

Lastly, where in the system should fuel flow and/or pressure be measured and what devices do you use to take the measurement?

I guess I'm not concerned that I'm restricted on air but should I be?

thanks in advance

Old 07-08-2001, 06:02 AM
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Your fuel lines could be clogged, or the line has these fuel filters that are clogged. In my case I had too much of these filters, there was very much rust in the tank, part of the rust particles blocked occasionally the fuel lines and I had to stop to let the particles float back to tank.

Old 07-08-2001, 09:44 PM
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Hello

Not geting full throttle says that the linkage might be worn.

Now what kind of injection do you have ?

The flow is fixed by the injectors. Now the Cis uses the pressure to adopt the flow to the engine demand.

The Motronic uses pressure and pulsing time for that.

Messurements can be done at the usuall ways.

Porsche are not american cars with undersized fuelpumps and missmatching manifolds. There is no need for double pumpers in a stock powered porsche, they have even enough reserve to cover major power upgrades.

Grüsse
Old 07-09-2001, 01:04 PM
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What engine,year, upgrades, etc. are you talking about........Ron
Old 07-09-2001, 02:38 PM
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I have a 1979 SC with CIS. Thanks for responses. Sounds like the key measurement is pressure and I should focus on the efficiency of my injectors. They have never been replaced but I do use Techron regularly.

Old 07-09-2001, 07:22 PM
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