Electrical help.
 

Have had my first ever "not easily solvable" non start.

Fired her up this arvo, after running for a few seconds, it spluttered once, fired up again and then died. Tried again, started and ran for about 3 seconds an then died again.

Starter motor doesnt go, nor does the fuel pumps which normally would with ignition on. The starter bypasses the ecu so Im pretty sure that is not it.

Started diagnosing - checked all the fuses - all good. Started checking all the wires around the starter motor. The insulation around some of them had coped a battering from heat from the headers, and its possible?? I had one short out. have 2 fusable links - one to the alternator and one for battery 12v to the fusebox and they all tested OK.

This is the part that has me stuffed. Pulled the starter out and wired it back up - so not grounded. Checked the starter relay (checked from behind the relay block), getting 12v on the switch wire when cranking, getting 12v on the out wire to the starter when cranking if the starter is not earthed. When starter is earthed Im only getting millivolts. Thought the starter solenoid could be fried so I pulled it all the way out and it tested fine.

So have i got another short to ground somewhere or a bad earth? I have managed to keep most the smoke in wires so far.

Any advice appreciated.

Cheers

when going at a problem like this I always look at the obvious things first. best to start with the battery connections first. Another thing to do is leave your negative lead on the battery terminal so your not guessing about the ground source. Then proceed with the other lead of your meter to check if your getting power to the other items downstream. Remember electricity flows just like water, so just follow it through its course

Andy and couple of "process of elimination" things come to mind for me:
(pls excuse if you have already done so)

- Try different battery - I've heard a battery may have "volts" but might not be able to handle the "current".
- bit out of left field - try roll starting? this will show if its the starter
- Does the starter "click" - indicating the solenoid is working?
- maybe the starter motor (excluding solenoid) is buggered.

Re-reading your message you mentioned it died a couple of times which doesn't necessarily point to the starter as the engine was running and then died which would mean the starter wasn't engaged. I am thinking battery again??

cheers

Gregg

Dont think its the battery or starter. Took the starter out and hooked it up to the battery with some jumper leads and it looks fine.

1.Run a jump wire from neg. on the battery to bellhousing/starter motor bolts, that would check earth.
2.Then, disconnect pos. on battery to starter motor input and run a jump lead. This would check that cable.
3.Run a jump wire from starter input/switch terminal on the solenoid and touch it on the battery positive. This would bypass the ignition switch.

My guess is the main wire from battery positive to starter motor is buggered.

Cheers

Dave

Ill give that a go this arvo - thanks Dave.

Has anyone built\designed a heat shield for the starter motor on LS engines- definately need something in there.

thanks for the idea :)

maybe it's worth looking up your engine type/starter motor part #... and see if there is a GM heat shield part # for it.

like this:
HEAT SHIELD | Genuine GM | 12623360

Do you still have the Piranha immobilizer fitted?
When mine is enabled, i get no crank, no fuel pump.

When I received my LS1 it had a clip on heat shield for the starter motor.

I haven't put it back on as my headers tend to head to the front of the car before they head downwards.

(I think it is on the Commodores because the stock exhaust manifold is a lot closer to the starter motor)

Will take a pic tonight. Maybe you could find one at a wreckers for a 6L etc.

A possible solution to shielding the starter.
DEI Versa Shields 010402 - Free Shipping on Orders Over $99 at Summit Racing

Immobilizer? Well, hell...that would be the first place I would start!;)

Double checked and even bypassed the immobilizer - Im sure it is fine. Actually the first thing I checked because I had it play up once before.

My starter motor slowly died over a year, here was me thinking it was the battery. the wiring has slowly broken down on one of the fields and eventually it couldn't turn the car over, bougth a new battery thinking that was the problem as the starter would bench test fine. only on closer inspection pulling the starter apart did i discover the problem.
1 new CVR starter and a proper high CCA battery and all is good.

That Im not getting the fuel pumps running makes me think its more than just a starter issue.

Ignition switch? I'm just guessing here and have had to replace a couple in the past due to similar issues...

OK - still struggling for a solution....

Put starter back in and hooked up cables. Found the earth strap to the engine from the chassis bolt was a little lose - thought that was it. Tightened that up. No luck.

Ran a cable from the positive battery to the lug on the starter - nothing. Ran a cable from the battery earth to the bolt on teh starter - nothing. Double checked the immobiliser again. Nup.

Any more ideas?

Sound like your not getting a "switched" 12V from the ECU to turn on the fuel pump relays? or 12V from the fuel pump fused circuit etc. Do you have 12V/IGN to the ECU etc?

I had the same symptoms the other day and it was a loose wire on my IGN Kill with on my dash.

is your ecu on a constant power or is it switched by your key ?
have you checked to see if constant power is not got some sort of break down
I had trouble with my battery isolator that caused similar troubles so ,now no isolator on hot wire to ecu


its a thought
rob

Check the power at the key. If the power at the starter main wire is good, then the solenoid feed from the key must be bad