Is this an automatic or 4 speed? The mileage is fairly typical. If the O2
sensor is working it has the final say over the air flow meter. If you smell
hydrocarbons, (why you think it is running rich) then you need to look for
ignition or lean miss fires and check the compression, leak down test to
check the valves. You may also need to check the catalytic converter for
clogging.

Dennis

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
Dave Arthur
Sent: Monday, May 18, 2009 6:22 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Digifant 21. MV High Fuel Consumption

I need some opinions... I have just returned from my first 'real' trip with
our Westy. I was a little shocked at the fuel consumption and yes there are
no leaks :-)

For 183 km I burned 24.5 litres 13.3 litres/100km. And for my American
friends ... 17.3 mi/gal (US). I was driving on reasonably flat terrain with
a maximum speed of 65 mph (105km).

The engine seems to run well, I have the o2 connected, it's new. From my
days of tuning MG's I'd say she is running rich, but the engine ECU is going
closed loop (I checked the o2 voltage with a high Z DVM, it swings up and
down) and I'm not entirely sure where I should look for the problem.

The engine idles reasonably well, goes on high idle when started cold and
drops to a steady 750 when warm. No stalling problems.

My only thought is the Mass Air Flow sensor may be out and or the air
temperature sender in the MAF.

The pressure regulator seems to work, pressure goes up and down in sync with
the manifold vacuum. I do have a bad check valve in my fuel pump, but can't
see how this would effect the mixture.

No maybe, this is normal fuel consumption, in which case I'll mortgage the
house :-)

Dave

'86 Westy