Cold Start Problem - Battery Issue?

Atari · 5 Dec 2013 at 10:38

Hi all,

Hopefully you knowledgeable folk are able to help me with this one. I've been having some trouble with my car starting in the morning with it taking a few extra cranks to get started, and then the car running rough for a few seconds before returning to it's normal peppy self.

Prior to this happening, I replaced the fuel pump in the car as the old one had 'stuck' and couldn't be started. During the process, the battery went completely flat and was jumped back into life (car started up fine).

Since then, the car always has a bit of trouble/hesitation when starting first thing in the morning (so being left for about 12 hours). It starts up perfectly fine during the day after this though so lunchtimes etc are perfect.

I've had a multimeter on it the past few mornings before starting the car and it shows 12v, which I believe is healthy - I understand running the battery completely flat can cause problems with it, but is there a way for me to test the battery under load (as it would when cranking)?

Thanks.

Tomsk · 5 Dec 2013 at 22:54

A healthy battery should be around 12.6V

MatteH Oxford · 6 Dec 2013 at 09:04

Before you buy a new new one (and if you have a charger or can borrow one), I would take the battery off the car & charge it for 12, preferably 24hrs, then refit it and see how the car performs. Check the electrolyte level too if it's not a sealed for life unit. You'll need distilled water to top up btw.

Charging from the mains is a lot more efficient than relying on the alternator, especially if the battery was discharged. Hopefully it will improve, I've saved many a condemned battery merely by charging it for a decent amount of time. I personally think it's good practice to take the battery off and charge it periodically if possible, I do this every autumn/spring.

Above post is correct re voltage, 12.6v @ 20c ambient temp.

Atari · 6 Dec 2013 at 09:53

Thanks all - I've got a battery charger at home so I'll try and give it a trickle charge overnight and see if that helps it out, I'm beginning to think it's a fuel delivery issue as the car starts but stumbles for a few secs with a very low idle rpm. Once it's woken up, it's back to it's usual self.

Hopefully it's the battery though, don't quite fancy buying another fuel pump

Conscript · 6 Dec 2013 at 12:46

Are you making lots of short trips? I'd be tempted to give the car a good run myself, see if that helps at all.

Amos91 · 6 Dec 2013 at 12:55

Try turning the ignition to the last stage before the engine starts to turn on (normally II) and back off. Then try turning the car on.

Wonder if there is an issue with the fuel pump not priming correctly from cold.

sovietspybob · 6 Dec 2013 at 13:16

As said could need a good charge, some cars have 'smart' alternators which only charge the battery under certain conditions. My Subaru for example won't charge unless the sidelight or headlights are on.

Atari · 6 Dec 2013 at 13:24

Conscript said:
Are you making lots of short trips? I'd be tempted to give the car a good run myself, see if that helps at all.

Hi, not at all, I usually tend to give it a good run and give it a chance to get to operating temp before turning it off.

Amos91 said:
Try turning the ignition to the last stage before the engine starts to turn on (normally II) and back off. Then try turning the car on.

Wonder if there is an issue with the fuel pump not priming correctly from cold.

I'm beginning to think this too, I always wait to hear the pump turn off before starting the car, but I've tried letting it prime 2-3 times and still have the issue.

I'm beginning to think it's the return valve in the pump leaking causing a low pressure situation when starting it after it's been left overnight - I'll hopefully have an OEM fuel pump off a mates car to test in mine so fingers crossed that'll sort it and I can get this one replaced by ECP.

Thanks again for the suggestions gents.