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Another day another gremlin


jon8710

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Good evening all 

I seem to be having issues with starting the car after it’s been sitting for a few days, I thought it was the battery but have changed it and it still seems to to struggle to start. 
The battery reads 12v but it’s will crank 2/3 times then die as if the battery is dead, if I put a booster pack on it will crank and start but then the next day won’t work again. 
Any thoughts? 
thanks 

 

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First of all, is it charging?  With the engine running at 3000 revs I believe you should be getting at least 13.5v at the battery.  
Second, when you say ‘won’t work again’ do you mean won’t crank or won’t start?

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11.5v is a fairly flat battery.  It should be over 12v if it’s a new battery.  Put it on charge & try again

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Update on this, 

I gave the car a long run out on Friday and all was well. 
I want back to it Saturday and started no problem so thought I might have blown out the cobwebs. 
Sunday again started fine and drive off only to notice the battery light flash a few times so I pulled over and turned the car off to see if it would start ok and it wouldn’t crank!

The dash lights were on but when I turned the key it wouldn’t turn over and there was a kind of straining sound from the front of the car??? 
 

i connected a booster pack and it still wouldn’t go, after many attempts and fiddling around with relays ect I noticed my lights were still on so I turned these off and it then fired, not sure if that’s related or just to do with the fiddling. 
 

I went out last night and noticed the battery light is on constantly but very very dim. 
 

Any advice is much appreciated as I’m starting to get a bit frustrated with this one. 
 

cheers 

jon

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One other thing to mention is before any of these issues I would notice the battery light flash every now and then when I drove the car hard, it would flash around the 5k revs mark sometimes. 
thanks 

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Hello all 

I whipped the alternator off and noticed the positive wire was loose and the negative was slightly melted, the alternator was replaced by the last owner a few thousand miles back and after a test it was confirmed by the man that it was all good so hopefully that will cure it. 
 

my next issue is now it’s all back together I went to test and I’m getting a kind of straining noise from the front of the car and it won’t crank, kind of sounds like a starter trying to turn but obviously is not. I’ve had this in the past few weeks a handful of times but it would finally start, now it’s sat for a few weeks it won’t crank at all. 
i will try to upload a video shortly. 
Any thoughts 
thanks 

 

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Difficult to understand what a straining noise is but the only thing in the front of the car that matters in this context is the fuel pump.  Maybe your fuel pump is tired and/or dying. Is there any way you can get close to the fuel pump whilst someone tries starting it, just to see if the noise is coming from there?

The other thing is if it is now not cranking and your alternator was slightly faulty with regard to wiring, does your battery still have enough charge?  Worth checking with a meter if you have access to one 

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Sounds like the fuel pump running when you go for a start which is normal. You would usually not hear it because your starter would be going at the same time.

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An SC has a safety switch way around the back of the inlet. This prevents the pump running unless air is lifting the plate inside the inlet. However it is over-ridden during cranking by fuel pump relay so pump runs during cranking, engine fires and lifts the plate, pump continues to run. What (I think) you are seeing is the pump not running with ignition on (correct) but hearing it because the car is not cranking when it should be. 

In order to 'help' my local indie had disconnected the safety switch, and rewired relay to an ignition switched source of 12v therefore no power during cranking... caused all sorts of problems! 

Now you are going to tell me it's not an SC! 

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16 hours ago, Chris T said:

An SC has a safety switch way around the back of the inlet. This prevents the pump running unless air is lifting the plate inside the inlet. However it is over-ridden during cranking by fuel pump relay so pump runs during cranking, engine fires and lifts the plate, pump continues to run. What (I think) you are seeing is the pump not running with ignition on (correct) but hearing it because the car is not cranking when it should be. 

In order to 'help' my local indie had disconnected the safety switch, and rewired relay to an ignition switched source of 12v therefore no power during cranking... caused all sorts of problems! 

Now you are going to tell me it's not an SC! 

Hi Chris 

Thanks for the in depth insight, 

I'm just not sure as I have a fuel pump immobiliser on the car so when i put the ignition on i thin have to wave the immobilizer fob over a location and i hear the pump kick in, i then turn the key and get the straining noise you hear on the video. 

i might have to bight the bullet on this one and book it in. 

 

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I'm sure the straining noise is the fuel pump, mine sounds the same. Maybe your immobiliser is preventing cranking.... Hard do diagnose electrical faults over the internet but you'd do well to download the SC wiring diagram (it's in several parts, print, cut and join them together) and refer to that. At least that is a good starting point, although there are multiple reasons for wiring being 'messed' with over the years..... 

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2 hours ago, SurlySurdi said:

If the fuel pump is running then you can rule out the immobiliser

Not entirely, immobilisers may have 2, 3 or more circuits. Frequently the fuel pump and starter are disabled. Perhaps the immobiliser is still active on the starter circuit.....? 

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42 minutes ago, PeterK said:

Plus another one

 

 

 

Whereabouts are you ?

Hi the car is near Ware, Hertfordshire. 

just a thought if I were to remove the pump relay and try it and no noise would this determine it? 
mid it were the pump why no crank? 
Im 99% sure my immobiliser is just at the pump. 
cheers 

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Yes, if you remove the fuel pump relay that would prove whether the noise is the fuel pump or not.

The FP is not causing the no start, rather the lack of starter noise is allowing you to hear the FP.

 

As the starter is not spinning or making any ‘contact’ noises, potential causes include low battery.  To test this put the headlights on and try the starter - if the headlights dim materially, then battery is too low.  Next, poor power connection to starter or poor starter/engine earth (this is normally from the starter to the heel board, about halfway between the gearbox and the inner rear offside wheelarch), but I would expect at least a slight clunk of the starter trying to engage with these first three.  Other potential causes include failed starter solenoid or its electrical connection and immobiliser (as others stated above, immobilisers usually have multiple channels, but most commonly they interrupt fuel and starter).  If you know what you’re doing, apply 12v to the solenoid connection, but if you’re not sure then keep well away.

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