fuel consumption in 1989 740 high

[6763edward]

hi i have just purchased a 740 1989 2.3 fuel injected estate with 128,000 on the clock. the problem is its running at 16 mpg which is rather excessive has any one got any ideas. air filter is fine and so are plugs.

Any help would be appreciated.

thanks

['88740GL]

Does your car have fuel injection or does it have a carburettor?
If fuel injection it is a mechanical system (K-Jet) notice where the throttle cable is connected under the bonnet, on the roller drum, follow the linkage for the throttle and there should be a reed switch somewhere around there.

move the throttle drum from the rest position (without the engine running) and you should hear the 'click' of that reed switch open, then another clickwhen you release the throttle back to rest, if you don't or it doesnt click when you release the throttle, then you must adjust the clearance by opening the associated locknut and adjust the throttle-stop rest position.

The switch is an over-run device, which allows any vacuum build up inside the intake system to be released, e.i. when you are driving down a hill with your foot off the throttle, you will have a vacuum that can upset fuel delivery, so this switch controls a valve which allows air in to kill excess vacuum. If this sticks on during idle and throttle open sessions, it will burn more petrol, hence low mpg, same happened on mine, now i get 25-30mpg!