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View Full Version : Just replaced head and now won't start TB42E



Peacemaker
6th April 2012, 09:02 AM
Ok i've just replaced a cracked head on my GQ TB42E and it winds over but won't fire. It has injection pulse and spark. The dizzy cap is numbered in the correct fireing order and the leads are installed in the correct order. There is fuel and fuel pressure coming from the tank. As far as I can tell/see everything is connected, all hoses, wires, pipes etc. I was up till 4am trying to get it going....... Any thoughts? Dizzy wasn't removed so timing shouldn't be the issue..... But I'll doubble check that.

Peacemaker
6th April 2012, 09:23 AM
The head is a 2nd hand head that I got cleaned tested and surfaced from a carby 4.2 motor. (complete runing motor cost me $200).... Just thought I'd add this just in case it makes a difference.

97_gq_lwb
6th April 2012, 09:39 AM
Most common cause i see is the dizzy 180 degrees out Wind your motor over slowly watching the inlet valve on number one it should close before the top dead centre lines up then line your dizzy up with number one lead

Peacemaker
6th April 2012, 09:58 AM
I'll check it but the dizzy wasn't touched from when it ran so it shouldn't be the issue.

Yendor
6th April 2012, 10:47 AM
If you timing is correct how's your spark plugs?. I'll guess new, but have you removed and inspected them since trying to start the engine.

97_gq_lwb
6th April 2012, 10:47 AM
Yeah never mind me lol was thinking of an overhead cam engine for some reason.
Pull the plugs to see if they are wet .
Do a compression test whilst you have them out
Check them for spark earth them on the engine wind it over if they are all sparking.
Try a little fuel down the holes put em back in and see if it fires at least it will eliminate a few things .

Robo
6th April 2012, 11:45 AM
being efi check sensors connected.
TPS.
o2.
aac valve.
idle valve.
even if 180 deg out would recon you should still get some sort of ignition, albeit bad , but something at least.

Peacemaker
6th April 2012, 04:38 PM
No compression due to the exhaust valves being open. I adjusted the intake but not the exhaust..... All sorted now and for under $500 including head, machining, VRS set oils and filters. Stoked! ...... Any one want a free bottom end? Nothing wrong with it, just come pick it up and it's yours.

Robo
7th April 2012, 09:25 AM
where's the short mtr located