SOLVED - Non-starting 1.8 K series

[twincamtim]

OK, so I went to start the 7 this evening – turned off immobiliser, turned the key (ignition light on, pump buzzed as usual), pressed starter button…….there was a faint click from the engine bay but nothing else happened.

This has never happened before in 12 months of ownership. I had a previous 7 which had the K click so I tried rocking in 3rd gear and had another attempt but no change. I pressed the fuel cut-off switch under the bonnet but no change. I have checked all the connectors but nothing seems loose. It worked fine yesterday and the day before, and last week, and nothing has changed since yesterday (well, something has but I don't know what) so I am really confused  . What am I missing?

I have searched through some similar posts and they generally point towards batteries/fuses/earthing/ECU issues. I tried again but with the headlights on to see if they dimmed but they didn’t but not sure what that proves. Beginning with the simplest, I have put the battery on a trickle charge overnight and will try again tomorrow morning.

In the meantime, if anyone has a  please let me know!

Thanks. 

[SM25T]

Flat battery ? Dirty/loose/corroded cable connection ..... check all the big cables between battery .... starter .... alternator .... chassis ... red and black cables.

[Jonathan Kay]

What SM25T says + what's the battery voltage at rest and when trying to crank?

Jonathan

[revilla]

"ECU" 30A fuse will give those symptoms. Caterham originally fitted a lower rated fuse which tended to blow so uprated to 30A but a lot of cars still have lower rated fuses. "ECU" is a bit of a misnomer because it actually supplies the whole engine loom including the starter solenoid so if it is failing you can put the car away running fine and the fuse pops the next time you try to crank it. The starter relay in the MFRU is supplied seperately via the ignition switch so the relay still operates when you turn the key giving the faint click.

[twincamtim]

To Revilla:

I have no idea where the ECU fuse is located (I know I should know where all the fuses are.....but it's one of those jobs I never seem to get around to). Please can you direct me?

To the others: I will check these tomorrow.

To all: many thanks.

[Jonathan Kay]

What year and dash? Send me a Private Mail with your email address if you'd like the wiring diagram with the fuse layout.

Jonathan

[twincamtim]

Jonathan,

It's a 2001 Roadsport with a standard dash. I'll pm you shortly - plans would be great, thanks.

[SM25T]

Bottom fuse on the rail above the passengers knees. Let me know your email address via Blatmail and I'll send you a photo of the fuse rail.

[revilla]

@twincamtim - Sorry, I fell asleep! Hopefully Jonathan and/or Ian have sent you the info you need.

[john milner]

A faint click could be the MFRU (or replacement) relay operating. That in turn should operate the solenoid. Perhaps the solenoid has a problem.

http://www.alcester-racing-sevens.com/solenoid_service.htm

Personally unless a fuse has blown I would do the relay modification or replace it if it has been done before as it is an easy and cheap way to eliminate something.

[twincamtim]

Tried again this morning, after battery on charge overnight - no change! I guess that rules out the battery then (although I'll try and check the voltage at some point). Onto the next item, cables - I'll get to them later today, weather permitting. 

[SM25T]

Added fuse rail photo to my Dropbox folder. See https://www.dropbox.com/s/nkkzo5z5rq6jzr4/20131105_122316_resized_2.jpg?dl=0

[revilla]

I would check the fuse before worrying about tracing the cables through.

[twincamtim]

Fuse checked - it's ok. I might just change it to 30A anyway, as suggested.

Voltage checked - 13.16v, unchanged when I press the 'go' button......

[Jonathan Kay]

What's the voltage at the solenoid terminal that's connected to the starter switch when you press the starter switch?

For diagnostic purposes I'd then run a cable* from that terminal directly to the battery. Could just touch it on but I'd probably use a switch. Does it crank?

Jonathan

* At least as thick as the one that's there currently.

[twincamtim]

Ha, ha, ha, all sorted.......it was a loose wire  . The brown and white wire female spade connector on the starter "looked" like it was connected, but wasn't! I should have checked the wiring first, doh! Now I think about it I did drive down a cobbled road the other day and I bet the vibration worked the connector off, and so nothing actually changed 'overnight' but in fact changed whilst I last drove it. I've tightened the connector and refitted - starts like a good'un now.

Many thanks for all the advice, sorry for being such a twit  .

[Jonathan Kay]

:-)

Jonathan

[revilla]

These problems are always simple ... once you know what the problem is!  Glad it's sorted. I'd still change that fuse to 30A if it anything less or one day we'll be back to the same problem  

[OliverSedlacek]

Glad that's sorted. Finding a loose electrical connection is not trivial.