Fuel Consumption

Hi all,

My 1992 Volvo 850 GLT 2.0 20V has been drinking petrol for the past number of weeks. I was getting 30mpg and now I am getting 21mpg. Things done to date to rule out issues have been:-

Checked all pipes for leaks....there were none!
Changed the evapouration cannister......no change!

Now can anybody tell me about the vaccuum switch for the evap cannistor...I heard it can cause problems but where is it...I came across a couple of pipes going to the cannistor that meet at a T-junction...off of that Tee is a one-way valve...is this it? How can I check it?

Also, on the fuel rail there is a valve unit (I think) that takes the excess petrol back to the fuel tank...can this cause problems and could it cause my bad fuel consumption?

Everything has checked out with regards to emmissions etc so I am loosing the fuel somewhere other than the combustion chamber....I am going to give the car a full service next weekend and if nothing has changed then it has to go to a volvo garage...Yikes, the bill!!!

Does anybody know of a volvo indepedant in the Munster area. I am living in Waterford in Ireland.

Rgds,

Colm

[sholtby]

trying to think of some things to check...

Have you started buying fuel from a different garage?

Are any of the brakes binding?

Are there any fault codes?

Is the lambda probe OK?

Tried doing an engine compression test?

Check distributor cap, rotor arm, ignition leads and spark plugs.

Is air filter OK?

Does engine get up to correct temperature? If not it'll run rich.

That valve on the fuel rail may be the fuel pressure regulator. Is the vacume pipe connected to it and not split?

Simon

[ajm]

Funnily enough my car (same as yours but '93) has started drinking petrol too! Not quite as dramatically perhaps, but certainly consumption has noticeably increased.

I have no new suggestions other than those posted here already; but I think the full service idea is definately an essential first step.

My car is probably needing it's 120k service which quite a comprehensive one; the mileage isn't there yet but timewise I suspect things are needing replaced (I bought the car less than a year ago and it had sat for a couple of months previously).

My first suspects are the air and fuel filters, plus the flame trap. Next are the plugs and possibly leads - although what's visible of the leads looks OK superficially, I think 100k miles is enough to warrant a swap for "peace of mind" if nothing else.

My car isn't showing any fault codes yet, the only physical differences I've noticed are a slight hesitation when starting and the fuel injectors seem to be noisier than before.

I hope a simple change of filters cures your problem and mine!

AJ

Hi folks,

I carried out a full service on the car this monday and the results look good. On my last trip I got an average fuel consumption figure of 29.5mpg which I am happy enough with. What did I change?

Oil, oil filter, fuel filter, distributor cap and rotor arm. I know the last two items weren't needed but I did it anyway since the car had 124k up on her. Anyway, I am going to keep an eye on the consumption over the next few days and ensure things are back to normal.

I am still puzzled though as to where the petrol went...I never smelt any petrol, the engine performance never changed and there wasn't any warning lights to indicate that there was an excess amount of petrol been burned.....any thoughts on where my petrol went??

Cheers,

Colm

Hello Colm

When you say that you are now getting nearly 30 to the gallon is that on a run or just around town with all its stopping and starting.

mick

AJ,
When you mention "hesitation when starting", do you mean, lumpiness while running, or a hesitation from turning the key to the engine actually turning?

I ask this question, as if you have the latter, I have some tips for you to save your ring gear, and your wallet!!

Basically, you will be told that either your ignition switch is gone, which will cost around £50, or your starter motor needs replacing, around £100+.

In actual fact, all you need do is remove the starter, then remove the solenoid from the starter, and clean and lightly lubricate the solenoid.

All in....about an hour...if you've never done it before.

If the problem is lumpiness, sorry for boring you!!

Cheers

Nigel

[ajm]

Hi Nigel,

By hesitation when starting I meant (but probably worded badly) that the engine requires a bit more turning over before it fires than it did a few months ago.

I'll bear your tip in mind though, I have to say it's not one I'd heard before about the 5 cylinder engines. I find by reading about other people's problems and solutions here I have a much better idea of what to look at when something does go wrong, so the more tips the better.

It takes quite a lot to bore me when it comes to my 850!

Cheers,

AJ

Hi Mick,

When I say 30mpg that is just travelling to and from work. Round trip of around 26 miles per day of which 6 miles is in fairly free flowing town traffic but still doesn't get out of third gear!

Rgds,

Colm

[markas]

Hi guys,

Firstly another thing to concider changing even though it hasn't been mentions is the fuel pump relay. Mine occasionaly played upin the past, but decided to swap out at 9 years and 180k and is only 27 quid this stops the hestitation on starts too.

As for Fuel comsumption when i first had my car i had Goodyear NCT2 which i had had on my previous car too. being a very sticky tyres i only got between 25 to 28 miles to the Gallon. I have not been on F1's for a long time and i now get around 27 1/2 towny driving and if i am good 70mph and no more get 33 to 34 mph on a run.

Mind you i am a manic tinkerer so everything is always at its optimum and i do have over 209k on mine.

To get accurate figures i have for as long as i drive fill up to the top and do the maths and see are very accurate!

[Mike Smith]

Nothing to do with the colder weather is it, choke on for longer??
just a thought
Regards
Mike Smith
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96 850 GLT