Need help tb carby spark issues

[Lost_gq_td4.2]

Have recently changed motors over in my 89 GQ the 4.2 carby manual got a long motor minus dizzy and carby drove the car in to where I was working changed it all over put my dizzy and and carby on new motor but can't get it to run has very weak spark did have a pentrix in it changed back to brand new points and condenser and new coil and still nothing have tried another pentrix out of another running car and still no good has 12.6 volts and the battery and a 11.9 at the coil it's doing my head in thanks

[mudski]

Checked all earth points to and from the motor and batteries? All electrical connections making clean and making good contact? Maybe run a separate earth strap from the -ive on the cranker to the engine block?

[Lost_gq_td4.2]

Yeh have double checked earth's but going to go back though every thing to nite to make sure I haven't missed any thing

[mudnut]

The initial voltage on start up should be petty close to battery voltage. Page 12-14 of the Haynes manual (1988 models) shows the coil receives a reduced voltage when running, via a resistor.

Page 12-15 (1990 and earlier models) shows you get full battery voltage at the coil on start up and running via a link in the switch. It also provides a signal to the Engine Revolution Unit via the blue wire between the distributor and coil..

Check the voltage on the Red and /or White/black wires (depending on which style wiring you have) at the ignition switch.

[Lost_gq_td4.2]

Ok will check behind the switch tomorrow had a bit more of a play changed some earths and that and now starting to get blue spark still not big spark but it's a start

[Lost_gq_td4.2]

So checked behind the switch had battery voltage but winding it over would drop to 7 to 8 volts and was the same at the coil so wired in a relay to the coil so getting full voltage but only getting max of 9 volts coming out of the coil and wasn't really constant so really has me screwed

[mudnut]

All I can suggest is check the wires between the coil and distributor. Check the internal distributor wiring.

I have heard that some non genuine distributors are made of an alloy that doesn't earth properly so humour me and try clipping a lead from the distributor body to an earth on the chassis.

[BillsGU]

Had a similar problem with a different vehicle years ago and found the distributor shaft was 180 degrees out. Don't know if that is possible to do with yours.

[Lost_gq_td4.2]

Yeh have checked earth on dizzy and its earthed inside and out as for wires from the pentrix I've pulled it from a running car

[Lost_gq_td4.2]

Had a similar problem with a different vehicle years ago and found the distributor shaft was 180 degrees out. Don't know if that is possible to do with yours.

Yeh can be done but still should have good spark not weak spark can't even get a back fire out of it have checked timing more times than I've wanted to lol

[BillsGU]

Yeh can be done but still should have good spark not weak spark can't even get a back fire out of it have checked timing more times than I've wanted to lol

Not always the case. If the shaft is out of alignment the points may be opening at a time when the rotor button is not properly lined up with one of the contacts for a HT lead. Again, I have not worked on a petrol Patrol so I can't say for certain. A workshop manual should show how to test the correct alignment.

BTW, what gap did you set the points at or did you use a dwell meter?

[mudnut]

So you had someone stick their finger in the number one spark plug hole as you manually turned the engine over, to see that it was on the compression stroke? Or if you are by yourself, remove the other five plugs and manually turn the engine until you feel compression to make sure it is not 180 degrees out.