1986 Mercury Classic 50 won't start.

[shr2807]

I'm trying to get a boat seaworthy. I haven't used it in at least two seasons, and it's been stored outside. I just replaced the starter as it wasn't activating at all. Now that is working just fine, but I can't get it to fire up. I put in new gas and oil mix at a 50:1 ration and I checked the fuel filter. I had a bit of a hard time getting the bulb to prime the engine, but eventually I got it primed. It's possible I could have flooded the engine, but I let it rest a while and still no go. After about 5 minutes of cranking on and off, I got it to hit a couple different times and it ran for 3 or 4 seconds before it died again.

I believe the motor is a 1986 Mercury Classic 50, serial number is A949818

Any advice would be greatly appreciated.

Here's a short clip of the first time it tried to start. Just click on the image.



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[shr2807]

Re: 1986 Mercury Classic 50 won't start.

I let it set for a couple hours and tried to start it again. I couldn't get it to fire at all. Any thoughts on where I should start trouble shooting this and how to go about it? Thanks in advance for any assistance.

 

[oldman570]

Re: 1986 Mercury Classic 50 won't start.

Testing the plugs for good spark with a good tester should be done. A compression test will tell if there is good even compression. The only other item left is fuel supply. Compression, +fire, +fuel = motor running. You need to test for all of these to determine just what is causing the trouble. My bet is that you will find that the fuel system is the trouble if the motor has set for more than a year. JMO
Oldman570

 

[racerone]

Re: 1986 Mercury Classic 50 won't start.

The starters on these motors are easily ( very easily ) damaged by excessive cranking,-------A slow cranking motor like this will not start,----Check for spark with all plugs in and with all plugs out.

 

[shr2807]

Re: 1986 Mercury Classic 50 won't start.

Ok, well I bought one of those spark plug testers that you put in line and it lights up if your are getting a spark. The top two plugs showed spark at first, the bottom two did not. I switched it around a couple times and lost spark on all plugs. Some very weak spark at a couple times. I noticed a wire that was corroded and the covering had eroded away. As soon as I touched it the wire broke in half. The broken wire seems to from this box up into the top of the motor. I'm not familiar at all with what this is or what it does. Here are some pictures I took. I can crimp in a new piece of wire and see if that helps. Not sure if that is the cause of my problem or just another issue.

 

[oldman570]

Re: 1986 Mercury Classic 50 won't start.

You can repair the broken wire buy replacing it, but go back to where you find good insulation and clean wire. then solder the joint and heat shrink it or cover it with liquid rubber and electrical tape . This wire will cause the trouble of bad spark to the plugs and may be all that is wrong. After repair retest for spark and see if it fixed that problem. JMO
Oldman570

 

[shr2807]

Re: 1986 Mercury Classic 50 won't start.

Ok, I cut back the sheath that has 4 wires running in it, including this wire. I ended up going to about 3" before it goes into the top of the motor. I cut and spliced in a new piece of wire and reconnected every thing. There was corrosion and deteriorated wire all the way up. I tried to start and the engine got a spark right away. A couple times and it fired up and ran for a couple seconds before dying. Tried a couple more times in neutral with the throttle kicked up a bit and it fires and ran nice and clean for about 10 to 15 seconds before dying. It tried a couple more times but apparently I have lost spark again. My best guess is that the wire is bad further up towards the stator. Having never taken a motor apart, is getting to the stator an easy job? Do I just need to take the bolts out of the flywheel to access it? Is this something that someone is fairly mechanical do?

The fact that it did run leads me to believe that the motor seems fine, but I'm still having the electrical issue. My preference would be not to have to replace the stator if I don't have to. Hopefully it's just the wire but I wont know until I can see it.

 

[CharlieB]

Re: 1986 Mercury Classic 50 won't start.

That is the trigger leads that have corroded off.

You will need to remove the flywheel, the whole flywheel and not just the outer portion, and lift off the stator to get to the trigger. Either cut the wires all the way back, or replace the trigger.

BE CAREFULL not to switch any of the wire positions of the ignition switchbox. The trigger tells the switchbox which cyl to fire as well as when. Crossing one of these wires will have switched spark on two cyls and can cause engine damage. If you cannot be sure which new wire is which original color, just replace the trigger assy to be safe.

You may also want to clean those carbs that have been left un-used for so long. It is very good preventative maintenence.

 

[oldman570]

Re: 1986 Mercury Classic 50 won't start.

Charlie has it correct. You would be better off to replace the trigger as a whole, as the chances of being able to get good wire are slim most of the time. You have to remove the nut in the center of the flywheel and use a puller/lifting eye to remove the flywheel. One can be bought on Ebay for around $35.00. It screws into the threads on the inside of the flywheel. You should turn the motor to TDC so you can tell where the flywheel should be when done repair/replacing the trigger. A manual for the motor will be of great help and there are ones online if one cannot be found. The trigger can be bought at several online marine outlets also.
A good carb cleaning is also sound advice. JMO
Oldman570

 

[shr2807]

Re: 1986 Mercury Classic 50 won't start.

I think I'm just going to go ahead and replace the entire trigger as recommended(Thanks for all the help!!!!!). I believe I have access to a puller so I will work on getting the Flywheel off. Just to make sure, Oldman570, you reference TDC. I'm assuming you are referring to top dead center? Is that correct, or does it mean something. Newbie here.

I believe I have located the correct trigger for my motor, but would love to have someone confirm that this looks correct for my 1986 Mercury Classic 50. Serial # A949818. Would this be a quality one or would there be a better option. I'm just not familiar with these brands.

Mercury / Mariner Trigger: 134-6452

 

[CharlieB]

Re: 1986 Mercury Classic 50 won't start.

I didn't view the vid but one poster mentioned slow cranking speed.

This system has a minimum cranking speed of 300 RPM for the stator to generate sufficient voltage to operate the switchbox.

This requires CLEAN connections at both ends of the battery cables AND the starter cable. Disconnect and sand every surface, clean, and tight. The starter may need cleaning, disassemble and lightly sand the commutator clean, and lightly lube the bushings.

Make sure the battery is in good shape and fully charged. Charge it and take it somewhere to be 'Load Tested'. This will prove if the battery is fit for service.

Do these few things along with your new trigger and you should see a hot blue arc capable of arcing across an open gap of at least 7/16 inch. Those in-line neon flash tubes are pretty much worthless when testing an outboard ignition. These ignition MUST be hot enough to arc across that 7/16 gap in free air otherwise it may not fire the cyl at WOT as the air/fuel mixture adds a LOT of resistance once under compression.

Spark tester?/ 526087

 

[CharlieB]

Re: 1986 Mercury Classic 50 won't start.

I didn't view the vid but one poster mentioned slow cranking speed.

This system has a minimum cranking speed of 300 RPM for the stator to generate sufficient voltage to operate the switchbox.

This requires CLEAN connections at both ends of the battery cables AND the starter cable. Disconnect and sand every surface, clean, and tight. The starter may need cleaning, disassemble and lightly sand the commutator clean, and lightly lube the bushings.

Make sure the battery is in good shape and fully charged. Charge it and take it somewhere to be 'Load Tested'. This will prove if the battery is fit for service.

Do these few things along with your new trigger and you should see a hot blue arc capable of arcing across an open gap of at least 7/16 inch. Those in-line neon flash tubes are pretty much worthless when testing an outboard ignition. These ignition MUST be hot enough to arc across that 7/16 gap in free air otherwise it may not fire the cyl at WOT as the air/fuel mixture adds a LOT of resistance once under compression.

Spark tester*/ 526087

 

[oldman570]

Re: 1986 Mercury Classic 50 won't start.

TDC dose mean Top Dead Center of the #1 piston in the motor. The TDC mark on the fly wheel should line up close/on to a mark on the front of the motor. From my info on the trigger from CDI, it is the correct part for your needs for replacement of the trigger. As others have stated, the motor needs to be turning over at or above 300 RPM for the stator to create enough energy for the motor to start. ALL electrical connections have to be bright and shine for good contact and should be coated with liquid rubber, to keep the corrosion at bay. The video of the motor cranking shows that the motor is turning over fast enough for it to start in my thoughts. Prolonged cranking of the motor only damages the starter and should be avoided. When everything is set correctly, the motor should start fairly quick.
JMO Oldman570