K Click

[cr]

I was getting the click after hot running (and also when cooled down after having suffered it when hot)

 

So, with it clicking repeatedly when cold, I took a fly lead from the solenoid spade to the batt +ve and it fired first time.

 

Aha - relay mod, I thought. So I did that, but still got the click.

 

Connected the fly lead from solenoid to battery again - fired first time.

 

Reconnected the existing red/brown wire from solenoid and took it to battery - fired first time (so that wire is ok)

 

Took my fly lead from batt +ve to relay input (to replace the input from the tapped brown wire going into MFRU), and used red/brown to go from relay output to solenoid - fired first time.

 

So... I must have a current/voltage drop somewhere in the car wiring, because the 'ooomph' coming from the brown wire which I tapped into as input feed for the relay isn't enough.

 

Voltage at battery is 12.28v

Voltage at brown wire input into relay is 12.21v

 

Am I on the right lines?

Where do I look next for tracking this down?

 

Go easy on me with the electrickery stuff, and feel free to spell it out in noddy terms - I won't be offended!

 

 

(Car is a 2004 Roadsport K-series with FIA cutout switch.)

[Jonathan Kay]

How did you make that tap?

 

Jonathan

 

Edited by - Jonathan Kay on 26 Mar 2014 12:20:56

[cr]

Scotchlok.

I just opened the MRFU and checked the voltage at that pin and also the other two brown wire pins - same readings.

[Jonathan Kay]

Lots of people have found Scotchloks to be unreliable.

 

I'm not quite sure what you're testing but seeing full voltage (especially under low current conditions) doesn't always guarantee that there isn't an undesirable high resistance somewhere.

 

I'd remake that with spade or bullet connectors.

 

Jonathan

[revilla]

The voltage that you are reading doesn't tell you a lot as the circuit isn't under load when you are reading it. You only need a small resistance to cause a large voltage drop when drawing the kind of current required by the solenoid. Whilst investigation the problem on David Martin's car we found the same problem as you - there is resistance somewhere in the loom between the battery and the fee you are taking to the relay. We didn't have enough time to track it down precisely but in his case, whilst attempting to crank, the voltage drop through the wiring was as much as 4 volts leaving only 8 volts at the solenoid, but wouldn't have showed anything significant if measured while not cranking. In his case we did my wiring mod as per my Low Flying article but took the feed for the relay straight from an extra wire onto the battery to bypass the problem. I've know old fuses develop increased resistance (rather than actually blowing) so it may be worth replacing the 30A "ECU" fuse in the fusebox with a nice fresh one. If that doesn't do it you are left with having to track down a poor joint buried within the loom somewhere or simply bypassing it as we did.

[cr]

Ah, thanks revilla.

Just measured it while cranking: 8.37V at solenoid. Sounds familar!

Used feed from batt into relay and it was over 10V (I didnt hang around to see how high it went as I was doing a decent Mr Tickle impression with my left arm very close to the manifold!)

 

Unfortunately I can't take a wire off the battery (racing regs), but I assume if I poke around a little, I may find either the culprit or a 12v source which doesn't have the resistance/fault.

 

I'll also look at replacing the fuse.

 

@JK - I did remake the connection, but same result.

[Steve Sheldon]

Just fit a proper starter motor - Powerlite - and you will not have heat problems. Yours is cooked! If it worked when new, it is nothing to do with the wiring.

[Roger Ford]

Quoting ssheldon: 

Just fit a proper starter motor - Powerlite - and you will not have heat problems. Yours is cooked! If it worked when new, it is nothing to do with the wiring.

 

It was new 10 years ago, as was the wiring. The fact that a direct feed from the battery works fine suggests it IS the wiring.

 

I'd take a feed direct from the switched side of the FIA switch to the relay power input (using a suitable stout wire), that then bypasses most potential resistances. The feed wire will need to go through the transmission tunnel as the relay and FIA switch are on different sides of the bulkhead.

[revilla]

12v at one end of a wire and 8v at the other also tends to implicate that wire.

[CageyH]

On the K, the solenoid feed passes close to the exhaust, and slowly cooks.

Replace the wire from the MFRU to the solenoid, and you should be fine.

[colindavies56]

battery should be 12.8,not 12.2.

give it a charge up.

[cr]

Thanks all for the suggestions.

 

@cageyH - I replaced the solenoid feed with a new wire instead of the red/brown. Same behaviour.

 

@colindavies - fair point. Charging now. It may have been a little low with repeated starting and start attempts.

 

I'll spend some time working round the loom to see if I find anything obvious. Otherwise, the fallback is the feed from the FIA switch. Thanks Roger.

 

[Steve Sheldon]

The wiring is NOT the problem. Your starter is cooked. Call the guys at Powerlite and they will tell you why. Mine had the same problem - same age - I changed to a Powerlite and it has not missed a beat for the last 3 years - car used regularly through out the year. The heat kills the solenoid. I would like to know the outcome and if I am wrong!!

[Jonathan Kay]

*arrowup*I'm sure that starters and solenoids can fail but in this case how does that explain this:

Quoting cr: 

Connected the fly lead from solenoid to battery again - fired first time.

 

Reconnected the existing red/brown wire from solenoid and took it to battery - fired first time (so that wire is ok)

 

Took my fly lead from batt +ve to relay input (to replace the input from the tapped brown wire going into MFRU), and used red/brown to go from relay output to solenoid - fired first time.

?

 

Thanks

 

Jonathan

[revilla]

Did you get this sorted??

[cr]

I didn't find anything obvious in the loom, and the FIA switch seemed fine, so I did what Roger suggested and took a wire off the switch to the relay input.

 

It now starts on the button, and I ran it up to temp and it started fine a few times.

So, it's definitely improved, I'll wait until next race event before declaring it fixed.

 

Thanks all for your help. Much appreciated.

[Jonathan Kay]

Well done, and thanks for the update

 

Jonathan

[Steve Sheldon]

My apologies. You were right and I was clearly on the wrong track. Glad it is sorted.