Starter Motor strangeness

[smash]

So I have an intermittantly firing starter motor.

I've taken the solenoid trigger wire off the solenoid and checked constant 12v feed when switching the ignition into cranking position. Did this several times and always constant 12v.

Next I used a manual push button switch wired to battery positive on to the solenoid trigger terminal - ervy time the starter cranked perfectly and no signs of playing up.

Then I reconnect the the trigger wire and crank from ignition swicth - instant intermittant starter motor again! WTF?!

I'm confused - unless it's the draw of the solenoid that's causing problems with the switch or wire as obviously a volt meter doesn't load it.

There's only one ignition switch on ebay and it's £75 bloody quid! Assuning it is the ignition switch...

Ho-hum...

[smash]

Would it be one of these?

http://www.rimmerbros.co.uk/Item--i-DRC3181?utm_so...

[wild rover]

How about a fused feed to a new relay triggered by the ignition feed. ?

[mrzigazaga]

Smash...Email me your address and i will send you one that i have..It came from a TR7 i believe but has the same four wires on it...The only thing is i had to put bullet connectors on it as the plug was naff and i needed to try it in a hurry...You are welcome to have it if it sorts out your problem...Ziga

[Wedg1e]

smash said:

So unless it's the draw of the solenoid that's causing problems with the switch or wire as obviously a volt meter doesn't load it.

Could be on the right track here... assuming it's not as simple as the crimp terminal on the end of the wire at the solenoid.
You could test by connecting the solenoid wire to a heavy-ish load, say a 21W brake lamp bulb, and see how/if it lights when you turn the key to crank. If that works I'd be tempted to go up to a 55W headlamp bulb but I'm not sure if the ignition switch is rated for 5A

[ruarirhodes]

I had a similar problem until recently, it turned out to be a broken solder in the fuse box causing a loose connection that would occasionally break (usually when stalled half way across a junction). Worth checking for dodgy connections in the loom as well.

[honestjohntoo]

smash said:

Next I used a manual push button switch wired to battery positive on to the solenoid trigger terminal - ervy time the starter cranked perfectly and no signs of playing up.

By doing this you identified the very common cause of starter failure, due to dirty contacts around the 'starter relay' base.

I might also be the relay itself, but first remove the starter relay and flood the connector/socket with WD40 or a proprietry switch cleaner, work the relay into the socket a few times and smear on some vaseline for future contact protection.

If its the relay itself, replacement is the obvious option, but they can also be dismantled and the contact innards cleaned.

After that check all the local wires and contacts around the relay and ignition switch for corrosion, including flooding the ign sw with WD40

[TVRleigh_BBWR]

You need to test the wire under load not just test if there is 12v, as the wire could have a big break and just barely connecting, this will allow it to show 12v but fail under load. as said try a high what bulb, or connect to the horn.

[smash]

I've checked the starter relay and that's firing OK - it holds switch constant even when starter motor is going off on off on. Also swapped a relay just in case it was switch contacts inside and still same behaviour by starter motor. So the culprit looks like it has to be the wire that goes from starter relay to starter motor solenoid...somewhere there is the fault.

Gonna crimp a new connector on first and then try and track back...

[SLB]

I've had intermittent starter issues before but only when hot. Turned out to be the earth lead from the battery to the engine was rotten in the middle so couldn't get the cranking amps. It might be worth you using a jump lead to double-up on the earthing to the starter and/or the ignition switch to confirm decent wiring and connections.

[hallsie]

The wires from the starter to the relay on the Taimar is a common fault apparently, and they get brittle which was the major problem with the one I picked up a couple of years back!

Try re-wiring the starter back to the realay, easy to say I know, but a temp job could be cobbled together pretty quickly!

Stu