no fire

[DLP321]

I have a 1978 Evinrude 150, with a short in the wiring from the motor to the key switch, problem is i cant find it, the motor will start sometimes, and other times it will not.The motor turns but no fire to the plugs. Is there a way i can test each wire cumming out of the key switch to the end of the big plug in the back. I replaced the key switch thinking that this was the problem. It wasn't.. please help ..... thanks

 

[F_R]

Re: no fire

How did you come to the conclusion there is a short? Well, that is possible, but not very likely. Be careful, "test" improperly, and you can blow the power pack (s).

You need to know that what you are attempting does not make sense. The ignition is always "on". The key switch only turns it "off". It does that by grounding the black/yellow striped wire. So testing voltages from the key is futile.

Simplest test is to unplug the big harness at the motor (don't disconnect anything else), then use jumper cables to run the starter. If you have fire at the plugs now, well then maybe you do have problems forward of that point. Still no fire? Then your problem is aft of the plug.

Once you isolate the problem to a general area, you can zero in on the real cause.

 

[DLP321]

Re: no fire

Thanks for giving my problem some thought. After finding out that the new key switch didn?t fix the problem I took the boat to a boat shop the mechanic tested the motor kind of the same way, he told me the problem was between the motor and key switch.

 

[DLP321]

Re: no fire

I have looked at the key switch wires and followed them from the key switch down to the big plug at the motor, and found no obvious damage

 

[DLP321]

Re: no fire

Also when I took the boat to get tested, [thinking it would be a quick fix]...he told me that the motor was only firing on 3 cylinders. And that I needed 2 new power packs. I paid him for his time and took the boat home. I couldn?t afford to let him do the work. When I got the boat home I checked the wires coming out of the key switch to the big plug at the motor. In the process of this I tried starting the motor and it fired up and ran. So I checked to see if I still had only 3 plugs firing and found that I had 5 out of six firing. #4 cylinder wasn?t. I shut off the motor and re started several times no problem. The next morning I tried to start the motor, same thing the motor will turn but with no fire.
That?s where I am at rite now.

 

[emdsapmgr]

Re: no fire

Ignition problems are difficult to diagnose, esp when you have no fire at all. You can find some good troubleshooting infomation regarding these crossflow ignition systems at cdielectronics.com. You can do some tests on your own. 1. do the test that FR suggested. You need to know if the control box wiring is the culprit or not. 2. That engine has two idential power packs. One for the 3 plugs on each head. You can swap them for testing. If you have no fire on #4, swap the packs and see if you have no fire on #3...If the problem moves to the other head, replace one pack. Let us know what you find.

 

[DLP321]

Re: no fire

thanks,i will let you know

 

[DLP321]

Re: no fire

Ok someone told me that the black with the yellow stripe wire is the culprit and that I should try to disconnect it and try to start the motor, well I did and the motor started rite up. Before when I said that I had 5 out of 6 cylinders firing and that # 4 wasn’t, it was #5 that wasn’t firing. But when I checked it this time all cylinders were firing. I checked the blk & yellow wire and found no damage. Does this mean that I need a new power pack?