LPG lean out hwy trips

[GOVNOR]

I put straight gas on my 87 LTD 8 mths ago. About a week after it was installed I did a 200km hwy trip and got about 100km extra mileage per tank. Happy with that. General city driving i consistently get 320km from a tank. Now after the 1000km service, everything running sweet (and still is) only last weekend i did a 600km trip and didn't get any better fuel economy at all. I hit 305km on the trip meter when I reached a servo to fill up the tank. The tank took 50ltrs. So after 3hrs of hwy driving my system didn't lean out at all. Why did i get good hwy kms before the 1000 service and after not so good?
Maybe before the service it was running heaps lean? And the richend up the mixtures?

Specs:

4.1ltr Straight gas
Impco 200
Converter E or L?
APA tank A90
Still running AF meter.

Any thoughts?

Do you guy get better economy than this on the hwy with same setup?

[PSI_LTD]

i used to get 6 km per litre, when the car was n/a. that was pretty crap. now id be lucky to do 4 km per litre

[ltd351t]

hows it run with that 200? they are a very small mixer.

[GOVNOR]

hows it run with that 200? they are a very small mixer.
Pre 1000km service:

300kms per tank city driving
420kms per tank hwy driving


Post 1000km service:

320kms per tank city driving
320kms per tank hwy driving


Seems to run fine with a 200 mixer, I haven't noticed any power lose since converting to LPG either. What size mixers do most of you guys run or should run on a 4.1 then?

I reckon they have richened up to mixtures to much? They said it was running a bit lean (it wasn't starting easy).
I might play with the timing and mixtures and see what I can get from it.

[ltd351t]

Pre 1000km service:

300kms per tank city driving
420kms per tank hwy driving


Post 1000km service:

320kms per tank city driving
320kms per tank hwy driving


Seems to run fine with a 200 mixer, I haven't noticed any power lose since converting to LPG either. What size mixers do most of you guys run or should run on a 4.1 then?

I reckon they have richened up to mixtures to much? They said it was running a bit lean (it wasn't starting easy).
I might play with the timing and mixtures and see what I can get from it.

the 225 would be slightly better, failing that the 300A, then the 425, only problem with the EFI manifold is you are limited to what mixer you can use, but the 225 should fit on.

[TUF250]

i use a 225 on my motor and about 350kms around town with it. this tuned with good plugs, leads, higher comp etc.

its a good system with the L convertor, i have always had it quick tuned and am yet to experience a backfire