Fuel Problems - Ford Mondeo

sassy_one

atrixblue.-MFR-. wrote: »

sassy its going to be the alternator if you had new bat. there is never a brand new starter or alternator unless your car is brand spanking new and had a duff one from factory. they are all recons when you purchase one from motor factors or maindealer, they charge a surcharge on purchase refunded when your old faulty one is returned, that will be sent back to their supplier for recon then re ditribution (recycling effectivly).

oh and 2.5 v6 has 2 ecu modules. one under bonnet and one under passenger side wing! when one goes it trips the other out. air mass meters, and map sensors can effect MPG if one or the other is down.

Sounds as though it's getting more complex as we go on

I will have a look into a few things at the weekend and see what I managed to find, although the MPG have gone up today, the trip computer is still not working correctly

atrixblue.-MFR-.

sassy-one wrote: »

Sounds as though it's getting more complex as we go on

I will have a look into a few things at the weekend and see what I managed to find, although the MPG have gone up today, the trip computer is still not working correctly

have you tried holding down the trip computers reset button for a few seconds and then releasing it so it has reset properly after batt failure?

Gloomendoom

I'm really confused here. I mean, how the f can it be the alternator? The alternator generates electricity. To do that it uses fuel (indirectly), and if it was using that much more fuel it would have to be generating sh!tloads more electricity. Where is it all going?

Pew_Pew_Pew_Lasers!

scotsman4th wrote: »

Sounds more altenator than battery to be honest. Once started the alternator should be able to cope with any demands placed on the system.
I may be wrong, but if I am, someone will be along to shoot me down lol.

Not really. Mercedes have a habit of going beserk when the battery is knackered.

OP, test the battery first. Everything else can wait. Fuel additive won't fix a thing.

Rolandtheroadie

Gloomendoom wrote: »

I'm really confused here. I mean, how the f can it be the alternator? The alternator generates electricity. To do that it uses fuel (indirectly), and if it was using that much more fuel it would have to be generating sh!tloads more electricity. Where is it all going?

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.
3. Remove one of the terminals from the battery and with the meter set to amps, connect it to the battery and the removed terminal. Possibly leave 1/2 an hour and see what currents being drawn (allows all the systems to go into sleep mode). I've 90mA on the wifes car and this is causing starting problems when left overnight as it's draining the battery too much.

anewman

A slipping alternator belt produces a rather distinctive noise that is very noticeable, and usually happens most under acceleration.

sassy_one

atrixblue.-MFR-. wrote: »

have you tried holding down the trip computers reset button for a few seconds and then releasing it so it has reset properly after batt failure?

I've held down the button on the trip computer

The button the on left (further est away from the drivers side)

After holding it it goes into some kind of mode I am unaware of and the Haynes manual does not provide any details/help.

It goes into modes like 'Fuel' Revs' etc etc, all to complex for me to even consider touching.

How do I reset the trip computer?

See here for the display on the trip computer

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?VISuperSize&item=310265145559

Gloomendoom

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.
3. Remove one of the terminals from the battery and with the meter set to amps, connect it to the battery and the removed terminal. Possibly leave 1/2 an hour and see what currents being drawn (allows all the systems to go into sleep mode). I've 90mA on the wifes car and this is causing starting problems when left overnight as it's draining the battery too much.

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.

Rossy.

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

Rolandtheroadie

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.

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?