[W126 Coupe] Fuel Flow Rate

[Robert Karl Stonjek]

Thanks Markus,

My measured flow rate is 1ltr every 37.5 seconds.

So where can one measure fuel consumption in real time?

As the dual flow runs all the way back to the tank then I assume that one needs to have flow meters on both lines unless the rate from the pumps is absolutely rock steady so that measuring the amount returned is sufficient to calculate usage.

I have made a few changes to my car (560SEC Euro) but have no idea which is effecting fuel economy and by how much.  I would like to make a change, take the car for a 10k run around a set course and evaluate the effect of that change.  Filling the tank is OK for an approximation if one fills from near empty.  But filling from near full is quite inaccurate in my experience (don't know why this is so).

The changes I've made recently is to cut a large area of the front of the air box out.  In theory, one no longer gets 'cold air' from the front of the car.  But the lift in performance and fuel economy seems to challenge that assumption.  The response to throttle is immediately noticeable - vastly superior.

The other modification was nitrogen in the tyres and subsequent higher pressure.

I took a trip on the highway, 400km, and the fuel economy was 15% better than ever recorded on this run (despite carrying two passengers, an additional 120~130kg).  So I am interested to know which improvements are actually doing any good.  I also have a few other tricks up my sleeve but the frustration has been in getting accurate feedback from the car.

Thus the frustration continues...

Robert





Per the service manual, you should be getting at least 1 liter in 30-40 seconds.

Markus Meyer
mfm at meyerprobateproperties.com
www.meyerprobateproperties.com
Meyer Probate & Properties, LLC
484-919-9762 



  -------- Original Message --------
  Subject: [W126 Coupe] Fuel Flow Rate
  From: "Robert Karl Stonjek" <rstonjek at bigpond.net.au>
  Date: Sun, April 19, 2009 1:04 am
  To: "MB Coupes" <mbcoupes at mbcoupes.com>


  Does anyone know what the fuel flow rate is?  I put a fuel flow sender on the main feed line to the fuel distributor and it showed 1.6ltr/minute at idle.  I assume the fuel flows back to the tank.

  I had assumed that the system only pumped what it used, so that a fuel flow sender would tell me how much fuel the car was using.  Apparently that was not such a bright idea...

  Robert

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