Fuel Problems - Ford Mondeo

Kilty_2

I assume the tank is around the same size as in my Laguna II (68 litres) - so even if you've put £30 in a second time it still won't be full - it's an electrical problem, not a fuel consumption problem.

sassy_one

scotsman4th wrote: »

I'd think with that fuel consumption you'd smell it. As there had been a post by sassy about the battery, there seems to be an underlying issue.
My first thought was alternator not right because as Rossy said, eventually the car just wont go with the battery fully discharged (the alternator may be charging but not at the required level).
The engines slow to turn over now and the clock resets. Both happen to my Ducati with the dodgy alternator a couple of weeks after a full recharge.
My first and cheapest port of call would be the 3 things I've listed and cover a basic test on the alternator, battery and whether or not something in the car is draining the battery when not in use.
Sassy, when you put the second £30 of fuel in, what did your fuel gauge read?

I have today done a number of tests on the car and it's charging levels etc.

I had to go out this morning so when I did, the car failed to turn over at all, just a 'click click click' and nothing, no starter engaging or turning.

Luckily I had a spare battery on charge, although it doesn't hold a charge for very long periods, I put this on with jump leads and the car turned over.

Anyway, when I got home this afternoon I have taken the current battery out and put the other one I have in temporary.
I checked the trip computer and it has now gone from '- - -' to reading 32 Miles remaining in the tank! Hooray!

Now, I put the battery that was in there on charge and will leave it now on charge over night on a trickle charger.

Anyway, I have checked to see if there was any current being drawn from the battery when the key was out and all doors shut, and there is nothing being drawn at all.

So, I think it's highly likely that if once I put the current battery in and it works fine for a few days etc, it's the battery, I'm hoping!


When I put the £30 in, the gauge read half way up, and I think the tank is 62 liters, I have it written in the Haynes manual but that's in the car at the moment

Anyone know what the car will run like tomorrow? As I intend to take it up on to the motorway at speed (obviously within the law )

But I read in the manual it states that it will run at it's 'Factory default state' for 5-15 miles of different driving ranges.
Am I likely to get any backfire, misfire or coughing etc?
Just want to know what to expect so In know what is 'normal'.

I am going to be ordering a new battery in the week, so hopefully if it all goes well, it may have cured it the simple reset of the ECU and trip computer!

sassy_one

Rossy. wrote: »

If the alternator was defective then the car would fail to run once the battery was depleted.

Fuel injection, the ECU, fuel pump etc is all run by electricity so if the battery wasn't charging you wouldn't get very far.

I don't think this has anything to do with your alternator in fairness. It could be the dash clocks up the swanny for all we know.

Do you self a favour and get the car to a garage and get it diagnostic checked


You said you volt checked the battery - What voltage was it showing? You mention it changes slighlty at 4,00rpm but you haven't stated what output the battery is giving. This is vital IMO

Your battery needs to be outputting a minimum of 12V

On checking today with the engine running it's showing output of 14 volts around bouts with engine at idle speed (500 RPM)

optimus_primera

scotsman4th wrote: »

My very basic knowledge assumes a battery starts a car.
Once the car starts, the alternator recharges the battery and supplies power to everything else.
If the alternator is U/S, it wont supply electricity and the car will use the power in the battery. As this power supply is reduced, problems will start to occur (including but not limited to digital clock resets, faulty gauge readings etc).
So I'd be more likely to ask how the f can it NOT be the alternator.

Back to the start, heres what i'd do.
1. Get a digital electrical meter and connect it to the battery terminals on volts DC. Whats the reading. 12.4-12.6 ish I would be happy with.
2. Start engine, observe voltage. If it's between roughly 13.5-14.5, I'd be content that the alternators probably charging ok. Much higher or lower may point to under or over charging.

When you test the voltage with the engine running, switch all the elctrics on, lights on main beam,heated window,blowers on etc etc, you should still get a reading of about 14v from a healthy alternator.

Its pointless trying other stuff until you at least get the cars electrical supply sorted.

optimus_primera

I assume you have checked the wiring on the back of the alternator is all ok ??

sassy_one

optimus_primera wrote: »

When you test the voltage with the engine running, switch all the elctrics on, lights on main beam,heated window,blowers on etc etc, you should still get a reading of about 14v from a healthy alternator.

Its pointless trying other stuff until you at least get the cars electrical supply sorted.

I put the heater on and the lights/spots and radio as well as heated windscreen the other day when I carried out a quick test and it was showing 14.2 Volts near enough, sometimes rising a tiny tiny bit but not much but defo not dropping.

I think it is the battery, and the only way to check this is to see what happens tomorrow with it fully charged on the trickle charger.

Again, does anyone know how the engine will run up on starting it after resetting to 'factory mode'?

sassy_one

Jeez

Guys, just read in the manual that now I've disconnected the battery, the KAM will be reset and need to relearn its values, I understand that but it then says 'Try and keep the idle speed close to the idle speed it was running at before' How the HELL am I meant to do that, what will it run like?

Okay, if it idles at 100 RMP, I can rev it up to the normal idle speed, but what if it starts idling at 1000 RPM? I can't stop it revving!

Please advise as I'm a little nervous now starting it!

anewman

Just drive as normal.

Rossy.

sassy-one wrote: »

Jeez

Guys, just read in the manual that now I've disconnected the battery, the KAM will be reset and need to relearn its values, I understand that but it then says 'Try and keep the idle speed close to the idle speed it was running at before' How the HELL am I meant to do that, what will it run like?

Okay, if it idles at 100 RMP, I can rev it up to the normal idle speed, but what if it starts idling at 1000 RPM? I can't stop it revving!

Please advise as I'm a little nervous now starting it!

Idle speed should be around the 900rpm mark as standard anyway.

It won't rev on its own so turn the key and let it idle for a sec and then take a nice steady drive and it'll relearn it values

atrixblue.-MFR-.

Gloomendoom wrote: »

So what are you saying, that the excessive fuel consumption is just a faulty gauge reading?

I must admit that that was my first thought, but the OP has confirmed that the tank was refilled with £30 of fuel after just 34 miles. It doesn't look like a faulty gauge.

what i am saying is that the op had a faulty/flat battery this sometimes causes the computer to FREEZE and read zero to everything. OP had a new battery and was concerned about the gauge so resetting the trip computers memory may of helped sort the problem, as i said a number of things can cause excessive fuel consuption, MAP,MAF,IDS,lambda sensor,faulty catalytic converter, faulty coilpack,faulty crank sensor,faulty cam sensor. i was merely suggesting a cause to one problem and listing a few other for the fuel wich you may not have read properly.