Excessive fuel consumption - my '85

[77CVT]

....and no it's not from my right foot this time!  

I checked the fuel pressure and it's on 40psi (30 with the vacuum disconnected) so that hasn't changed (adjustable regulator).  The bleed off valve took forever to de pressurise even after we took the fuel pump fuse out and ran it till it choked.  It still had heaps of pressure - that doesn't seem normal!

It chews it at low speeds (15-25 l per 100) but on the highway it gets about 8-9 l per 100.  This has only happened the past month or so.  You can actually see the average creep up to 19 l per 100 around town!  Over 70-80kmh you see it plummet down again.  It only ever ranged between 11-14 l per 100.

There's no black smoke either and No 1 plug is reddish on one side so it's definitely running a bit rich (No 3 was ok).

The O2 sensor & coolant temp sensor (under throttle body) were replaced about 4 yrs ago.  It's running NGK Iridiums & 9mm leads.  I wonder if it's the computer as when we connected it to the laptop we could only get a couple of lines filled in the tables.  

Could it be the diaghram in the fuel regulator?  If the MAF goes it would throw a code surely or at least wouldn't make it think more air was going through it?

Nothing's making sense.  Any ideas?  

[BlueVette]

I still would check the mass airflow sensor (MAF), it determines the fuel-air mixture for the engine.
It's TPI not crossfire, right?

[77CVT]

Yep TPI.

I'm getting better economy on the h'way but worse around town.  :rolleyes:

There was no fuel pressure leak down after the engine was turned off either.

[gtc]

It chews it at low speeds (15-25 l per 100) but on the highway it gets about 8-9 l per 100.  

Those figures are very familiar to me. Are you sure nobody slipped a big block in while you weren't looking?

[77CVT]

I wish!  

[gtc]

I wish!  

Not if you're worried about 25L per 100.