1978 Mercury 85HP No Spark?

[Shadow662]

My brother had his boat out a couple weeks ago. After we put a new impeller in and she ran fine. However, today we took it out and she started we backed up off the dock put it in forward gear and she stalled. Tried to start found we didn't have any spark at the spark plugs or the coil. Anyone got any ideas. I read somewhere about a "switch box" how can I test that?

Thanks,
Nick

 

[Laddies]

Re: 1978 Mercury 85HP No Spark?

Here's the ign system test.

 

[Shadow662]

Re: 1978 Mercury 85HP No Spark?

Ok well I went threw the test and I found that I don't have any voltage on the green wire from the switch box to the coil. I don't have a CD tester to test the distributer. Any thoughts?

When they talk about the "trigger" what are they referring too? I can't find anything in the parts manual for "trigger"

 

[Laddies]

Re: 1978 Mercury 85HP No Spark?

The trigger is the part in the dist. hsg. that fires the system, if you do the arc test on the top of the page and you have spark, the trigger is bad and ifyou don't the problem is the coil if there is voltage on the green wire or if there is not it's the switch box. Tere is no need for a tester.

 

[Shadow662]

Re: 1978 Mercury 85HP No Spark?

Ok, I did the test at the top of the page and have spark. Now I need to know what the "trigger" is. I am looking at a parts page at crowleymarine.com here:http://www.crowleymarine.com/mercury_parts/461/40.cfm
The number i belive it is is #4. But that is the whole distrubuter housing. Do you know if I can get the "trigger" seperate from the whole housing?

Thanks,
Nick

 

[Laddies]

Re: 1978 Mercury 85HP No Spark?

Yes, thats the part it only comes a assembly as the trigger is potted into the housing. The CDI part is the best choice Part number 134-3736. better quality and price.

 

[Shadow662]

Re: 1978 Mercury 85HP No Spark?

Ok, thanks for all your help.