Fuel gauge, economy (late Turbo)

[944Tman]

Hi

I have owned my 1991 944 Turbo (250horse) for 8 years, covering 49,000m, it now shows 149k. Its properly serviced etc.

My fuel gauge goes down rather quickly and in odd stages, like it sticks - for example, first quarter can show as gone in around 30 miles, half way takes about 160 miles and the red light comes on about 310 miles. I fill up within 10 miles of this.

The most I ever got from a tank was 366 miles, that was 72 litres ( and £102!).

There is also the whiff of fuel near the filler cap.

My driving is enthusiastic but smooth, journey to work ( daily driver) is 7 miles over country roads/A1 and then long A1 runs of 55 miles weekly. So I'm getting poor economy - or is this normal ? And the smell of fuel and way the gauge works suggests something is amiss with the tank. I had new fuel lines last year. I have also tried running on a half tank or less (£30) but no change in aroma or economy.

Any thoughts or advice would be appreciated. Thank you.

 

[rav]

After a long run check if your wheels are hot. Place the back of your hand on the alloy itself.
It could be that your car is suffering from the dreaded caliper plate lift, causing the brakes to bind against the disc.

I have a 220 turbo and the fuel consumption is quite poor especially if driven quite hard.

 

[Lowtimer]

The fuel economy is quite sensitive to driving style, as with most early petrol turbo cars, but yours seems thirstier than it might be. However, in my experience you can use lots of acceleration and still get respectable fuel consumption. What will absolutely drink petrol is heavy use of the brakes across country, because then you are throwing away all the energy you have just paid for.

Your best tankful is 23 mpg, which seems poor. I get 29 or 30 mpg driving normally on my usual 160 mile long run, which is a combination of about 50 miles on derestricted open A and B roads, and about 110 miles of A1. That's cruising at the same sort of speeds as the quicker elements of the turbodiesel company car fleet on the dual carriageway sections, and showing a clean pair of heels to anything else on the rural roads, unless maybe I happen across a local Scooby or Evo hero in which case I generally defer gracefully. If I am out for a play in the Dales, North Yorkshire Moors or Northumberland, I generally get 24 or 25 mpg, though that does include a bit of driving in amongst the ordinary traffic to get up to the good roads..

It shouldn't smell petrolly, by the way, so you have some sort of leak around the filler neck.
It seems normal for the gauges to dismiss the apparent first quarter of the tank quickly, but you may have a sticky sender. Mine failed when the car was standing for a couple of months last year and I have a new one now which is a bit smoother.

 

[barks944]

The 944 turbo seems to burn pretty rich as its quite a basic injection system and it doesn't know manifold pressure etc. All sorts of issues can make it burn richer too. Worth checking fuel rail pressures, air flow meter, temp sensors etc. Check out clarks-garage for a good set of guides.

 

[944Tman]

Thanks chaps.

Clearly I have several problems - my wheels do get hot, and my current front pads haven't lasted long, but I am fitting the self returning sticky things this time which I think we omitted last time. That may sort that issue. Will investigate the neck of the tank too.

My driving style is much like Lowtimer, and I do recall, immediately after a major service last year, on holiday in France, cruising at about 85-90 with bursts well over the ton, of getting 28-29 - so you're right, braking does kill economy due to lost momentum. That economy level didn't last long though.

All the diagnostics on fuel mixture etc are showing very good, I have the use of the MOT station next to us to check these things, so no worries there.

Much appreciated.