1975 1150 intermitant spark

[pegithard]

i have a 1975 1150, the spark keeps coming and going,i will run in the driveway then not at the lake, then drive home and it runs again, then back to the lake and it will run for hours no problems, motor starts instantly when it has fire. i just installed a new internal harness, motor started right up ,and then it was like someone turned off the key,now i cant get fire back. please help.

 

[daveswaves]

Re: 1975 1150 intermitant spark

The most likely culprit is your kill switch or mercury switch. Any short in the circuit will stop it from firing. Look for bare wires etc.

 

[timmathis]

Re: 1975 1150 intermitant spark

I had the same thing with my 1975 150 hp. It was the trigger. First check the switchbox if it is good then I bet the trigger is bad.
Go to www.outboardparts.com click on mercury then troubleshooting then click on print guide. Read on how to test the box and trigger. Good luck, Tim

 

[emckelvy]

Re: 1975 1150 intermittant spark

Re: 1975 1150 intermittant spark

I had one where the red Hot wire in the external harness was busted, and everytime you turned the motor the wire would part and kill the ign. Then when you turned back the other way, it'd join back together and you'd get spark again.

Easy to check, just wiggle the external harness and see what you get.

Another way to ensure you're getting power to the ign switchbox is to check the red wire for constant +12V, and also the white wire (on the same side as the red, not the white distributor wire on the other side) for +12V when the key is in the "ON" position.

For a test, you could jumper together those 2 terminals on the switchbox; just be aware that with the jumper installed the ign will be on all the time and can't be turned off without removing the jumper.

Or, power-up both of those terminals with a "hot" wire directly from the battery.

Check out this Most Excellent troubleshooting post, scroll down for the ign stuff:

http://www.iboats.com/bbboard/bbBoard.cgi?a=viewthread;fid=29;gtid=933928

HTH............ed

 

[Clams Canino]

Re: 1975 1150 intermittant spark

Re: 1975 1150 intermittant spark

Also.... drop the dist cap (wires left on) and check the carbon brush. Clean the inside of the cap with carb cleaner and Q-tips while it's off.

-W

 

[pegithard]

Re: 1975 1150 intermitant spark

i cannot get any spark doing the switchbox test, i am pretty sure im doing it right, i guess i will order a swithch box.

 

[pegithard]

Re: 1975 1150 intermitant spark

one guestion, with none of the wires to the ditributo connected how does touching the black wire to ground make the coil fire.

 

[timmathis]

Re: 1975 1150 intermitant spark

When you ground the black wire. What it is doing is just what the trigger does to make it fire. It is the only trigger test I know. Tim

 

[pegithard]

Re: 1975 1150 intermitant spark

i want to thank everyone for there help, i think i have finally found my little engine demon. i am getting oil in my distributor, i think where previous owner put to much greese in the fittings,i will have no spark, i can clean the cap and underside of trigger, let it dry and im back running. its just a pain to keep having to do that. if any one knows how to get the greese out let me know. thanks again for everyones help this is a great site.