1977 Mercury 1500

[dhendricks]

Ok so here's my situation I have a 1977 Mercury 1500 that is having spark issues. I have done a compression test and all 6 cylinders have excellent compression (130-135). The #5 and #6 cylinders are not getting spark and idk where to start. Any help would be great, thank you in advance!!

 

[jimmbo]

How are you checking for spark?

 

[dhendricks]

with a spark tester from a local parts house. one end hooks into the wire and the other end slides over the plug it self, it has a light in the middle.

 

[jimmbo]

That device leaves the spark plug in the circuit, try swapping a couple of spark plugs and see if 5 and 6 are still dead

 

[dhendricks]

i will give it a shot and let you know how it goes.

 

[Chris1956]

Unless the spark plug wires have been replaced, they tend to start to break down and leak voltage to ground. Numbers 5+6 usually go first. You should hear and see them sparking to ground, when the motor is running.