1985 Mercury 50 HP 4 cylinder - no start

[barrythedude]

Worked ducky all season, went for a final fishing trip and whirl but no start. Fuel is present, fuel bulb gets firm and choke assembly works. Disconnected level cutoff switch, same condition. There is voltage at the switchbox, but I am unsure what it should be. On the advise of a former boat dealer, I bought the harness to connect the switchbox to the coils (he said they were a common failure, but they looked/ohmed fine to me) the no-start still persists.

As I have voltage, can some one point me to either: the likely cause, or; what voltages should be where, and could the rectifier be of some problem here as well. Thanx to any and all who reply, simply great forum!

 

[barrythedude]

Re: 1985 Mercury 50 HP 4 cylinder - no start

Here is my original post from 8 months ago when it freshly died, if it provides more info (The symptoms: running great, start like a champ, one day went out, whirled for a while, but started, no other trubbles that day. Next week - no start - tried for 2 hours, whirl, but no start.

To date:
- Got a manual and wire schematic
- New plugs (needed anyway)
- From the from remote, tilt/trim works, choke snaps shut, starter engages
- a 5 dollar spark tester inline shows no spark (at any of the 4 coils)
- checked all wires and tightened where necessary
- There is a fuse in the cover bag but I am unaware of a fuse anywhere (can't find if there is)
- I removed the black w/yellow wire for the mercury switch, no change
- manual I have says has to be 210-320 v from a wire (really?) I only showed 40V

Now I am bamboozled, I am thinking stator or trigger plate, perhaps disassemble the remote handle and see what the harness connector looks like, but I have never done that. both unwelcome to me. Are there any other tests or troubleshooting any of you can suggest? End of season here, but taking the boys out for one more fishing trip before they are too old and cool for dad would sure be dandy. Serial number is 7221339)

 

[nickoli1]

Re: 1985 Mercury 50 HP 4 cylinder - no start

Bring it to a shop, if you have no spark to all plugs it will mean you have to pull the flywheel and replace some parts.

#1 Ground out your leads before you turn your motor over, otherwise you can trash the stator.

It sounds like you need a tune up kit. Or your stator/rectifier is junk. Do you have a multimeter?

 

[Maxz695]

Re: 1985 Mercury 50 HP 4 cylinder - no start

Sent you notification for future reference. Get the test proceedures from a manual for your engine to properly diognose the problem. Stators and switchboxes are tricky without the test hard to say what it is exactly

 

[barrythedude]

Re: 1985 Mercury 50 HP 4 cylinder - no start

I do have a multimeter, that is where I got the 40 volt reading from. Do you have something to test?

 

[barrythedude]

Re: 1985 Mercury 50 HP 4 cylinder - no start

Sent you notification for future reference. Get the test proceedures from a manual for your engine to properly diognose the problem. Stators and switchboxes are tricky without the test hard to say what it is exactly

I did have the test voltages from a service manual I got from the library, but it also mentions a special voltage tool, not a multimeter.

 

[Maxz695]

Re: 1985 Mercury 50 HP 4 cylinder - no start

a DVA? I nretested my startor not froma 50 HP but a 40 HP 4 with two yellow wires peg to 0 and the green wht wht green just under peg a little over the 0 not even half way to one maybe that will help some

 

[Maxz695]

Re: 1985 Mercury 50 HP 4 cylinder - no start

I sent results from a 2 cyl 2 stroke stator I beleive under 2 is acceptable 1.5 was my result connected blue to red yellow to yellow peg to 0

 

[barrythedude]

Re: 1985 Mercury 50 HP 4 cylinder - no start

My CDI diagnostic says blue-blue/white to be 1500-1800 ohms, but I am not getting exactly that. The rectifier test (try to start with both yellows disconnected) does not help, and disconecting the black-yellow wire to bypass the mercury switch also does not fire the engine. Gas is present, choke works, whirls like crazy.I also get 500-650 ohms as stated in the cdi troubleshooting guide. Am I narrowing it down to trigger plate?