Thread subject: Whaler Central - Boston Whaler Boat Information and Photos :: 25 Merc - Intermittant Starting

Posted by vibroluxe on 08/28/10 - 11:50 AM
#1

Driving me crazy... This guy will start and run great. Turn it off and come back an hour or two later and it cranks all day long and won't start. Come back tomorrow and it fires right up. ARGH! Checked the plugs when this was happening an no spark to either one

So I checked the resistance on the stator and it was lower than what the manual said it should be. Replaced the stator. Started it up and drove it around and it ran great. Started it 15 times at least - no problems. Went out to get some gas an 15 minutes later - it wont' start again.

Could the kill switch be my issue? Will the motor turn over if the kill switch is open? What's the best/easiest way to isolate the kill switch from the motor?

Or - is there somewhere else I should be looking?

1990 25 HP Merc with electric start and console controls

Thanks - John

Posted by Joe Kriz on 08/28/10 - 12:47 PM
#2

The motor will still crank with a bad kill switch.

You could temporarily put a jumper wire over the kill switch terminals to check that out or use an ohm meter between the 2 terminals to see if it is making and breaking connection when activating the switch.

Posted by vibroluxe on 08/28/10 - 1:12 PM
#3

So I would need to go into the controls and jump it from there?

There is a wire coming through the cable harness that is coming from the kill switch (yellow and brown I think?) through the wiring harness. Can I jump it from there? Or - hook up a temporary kill switch on the motor to see if it behaves better?

Thanks for the help Joe - John

Posted by Joe Kriz on 08/28/10 - 1:52 PM
#4

John,

I would just take the kill switch loose and then you can view the 2 terminals on the back of it unless this one is built into the switch.
My prior Mercury had a separate kill switch though.
Just jump the 2 terminals or check it with a mult-meter for continuity when open and closed.

Posted by DWinter on 08/28/10 - 4:03 PM
#5

It almost sounds like a float/needle valve sticking causing the engine to flood and not start. When it won't start, are you getting spark. If not, you could be in the right area with what you're already looking at. If you get spark, it could be flooded. You'll need to do a little more diagnosis to narrow it down.

Posted by vibroluxe on 08/28/10 - 4:52 PM
#6

Joe - OK, I will open up the control and see what is going on in there. Problem is that it is so intermittent, I'll have to catch it when it's not working. Another thought - if the kill switch turns out to be OK, could it possibly be a problem with the key/ignition switch?

Duane - when this problem happens I have no spark on either plug. Then it mysteriously comes back. Just had the carb rebuilt so I don't think that it is a fuel issue.

Thanks for the help guys - John

Posted by vibroluxe on 08/29/10 - 3:18 PM
#7

Well I removed the kill switch and so far so good. It started every time today. I'll make a few more test runs and if it still works well, I'll order me up a new kill switch.

Thanks for the help guys! John

Posted by stevebaz on 09/03/10 - 8:40 AM
#8

I had this problem with my Mercury 25 on my 11 footer and it was the wiring harness plug where it connects to the motor harness. I seperated the loose plug and took a jewlers screwdriver and slightly respread the connectors inside the plug and plugged it back in. This solved my issue. If you still have issues I would check that plug.