'77 Merc Tower of Power won't start - Video Link Included

[bsutravis]

The motor:
1977 Mercury 115 Tower of Power

I was at the lake, all was well until......... the starter solenoid seemed to crap out while on the water around midnight after a night of fishing. The solenoid would just click rapidly so we knew it was toast. In desperation I jumped across the solenoid with a screw driver which started the boat just fine so we continued to the dock with no issues. We went to put the boat on the trailer and had to restart the motor jumping across the solenoid again only this time the motor would turn over but didn't want to continue firing once it got it's initial fire. We used the trolling motor to get the boat to the trailer and got it home where I just replaced that solenoid. Unfortunately it still won't start, just like it did at the dock. It turns over good on the new solenoid and starts to fire but then it dies. I've pulled all the plugs and cleaned them all and I've got good spark to each plug. Could I have blown something in the jumping of the solenoid?

I'm at a loss where to go from here. It's getting fuel and spark..... it's acting like it's shorting out and killing itself the moment it starts to run. I've got a Seloc manual for it but I just don't know what to check next. Any help is much appreciated!

https://youtu.be/uRoPs1yDz2g

 

[Texasmark]

You shouldn't have hurt anything jumping the solenoid. I used to do it all the time when I was a shade tree mechanic on cars back in the '50's or so. Checked your battery condition lately? How about your high current wiring between the battery and the engine. The black and red wire connectors need to be disconnected periodically and cleaned and reinstalled nice and snug. A bad connection can keep an otherwise good battery from getting power to your starter.

See if squeezing the bulb keeps the engine running once it starts. If no change then get a can of Sea Foam Aerosol....WW has it or any auto parts store, pint costs $6-8. It contains mineral oil which 2 strokers need with the naptha and alcohol mix that starting fluids usually don't have....yes some do, but how much? While cranking with the throttle set fast enough to open the carb butterflies, choke off, shoot some SF into the venturis of the carbs.....all 3 going back and forth. If the engine hits and stays running if you keep squirting and dies when you stop then you have a fuel delivery problem.

If the bulb keeps it running look for fuel pump problems, cracked hoses or clogged lines/fuel filter. That'll get you going in your quest for the smoking gun.

 

[bsutravis]

Thanks for the reply Texasmark... Yes, I tried squeezing the bulb as it was turning over with no difference. I'll get some SeaFoam and give that a try later today. To me it sounds like it's almost shorting itself out or something the way it coughs like it's going to go, but then instantly stops and the starter disengages. This Merc is usually VERY easy to start. She gets plenty of use so that's why I am worried that I hurt something (Switchbox ???) when I jumped the solenoid to get off the water. I've already double checked my wiring to the battery and you can tell from the video that it's turning over like normal.

I'll try the Seafoam later today and report the results....

 

[jimmbo]

Bad ignition switch up in the control box?

 

[bsutravis]

I hadn't thought of the ignition switch jimmbo....... The last time I was in that Mercontrol box the wiring was pretty bad, but it worked so I didn't mess with it. I'll take a look at that as well.

 

[Texasmark]

Bad ignition switch up in the control box?

Think the ground at the off position is shorting to the on switch position? Probably metal migration from years of usage, or degraded phenolic insulator due to time and moisture? Good point you made since this engine is a '77 and that sort of thing could surely do it..

 

[bsutravis]

Where I'm at now.... I got sidetracked yesterday with replacing the front strut assemblies on my wife's mini-van, however I'm back at the Merc today. I opened up the Mercontrol and it was a mess. Insulation gone, bare wires exposed, etc. I cut all the ignition wires and soldered them back onto the ignition as well as fixed any other bad wiring in the control box. I then got looking at the wires coming down from the stator and they were HORRIBLE. I cut them and was able to get enough decent wire to splice into up under the flywheel. I also found a broke ground wire on the port side grounding strap at the back of the motor that I've fixed. I'm going to double check everything again and button it up and hope for the best. I'll report the results.... even if it doesn't fix my starting issue the wires certainly needed fixed!

 

[bsutravis]

Grrr... I buttoned it up and everything is the same. She turns over and the moment it starts to fire the starter disengages and it dies. Is there any chance this is a starter issue perhaps? The starter was replaced last year and it turns over great, but it does disengage from the flywheel the moment it starts to cough. I doubt it's the starter but who knows at this point.

One odd thing, for as long as I remember when you would turn power on to the ignition you could hear a very faint sizzle coming from the motor. It's always been that way for the past 20+ years of being the boat with my Grandpa, and now as my own after he passed away. The sizzle was always troubling to me but it ran fine so I never investigated it. Now however, do don't hear that faint sizzle when I turn on the key. Could this be the switchbox?

 

[CV16]

I'm not sure, but I'd think if you have good spark on all plugs, the switch boxes are fine. I had an ignition switch go out and it acted just like that.

 

[Texasmark]

Sizzle is something burning. Need to check it out with your eyes, nose and ears. Still could be the ign switch and an ohm meter could tell you that.

 

[bsutravis]

By ignition switch are you referring to the actual keyed ignition at the Mercontrol box? How would I ohm test it?

 

[bsutravis]

I found a used wiring harness that has a brand new ignition switch on ebay so once that arrives I'll install and go from there. The wires on my existing ignition harness are horrible so I'm hoping this does the trick.

 

[Texasmark]

By ignition switch are you referring to the actual keyed ignition at the Mercontrol box? How would I ohm test it?

You would need a diagram or know which color wire went to which connector. But I can help you with that. If the control box is a Quicksilver/Mercury Commander 2000 or 3000 Start is red wire/yellow stripe, power in from battery is red, red with purple stripe or purple is switched (from the ignition switch) power to operate things that you only want running when you are in the boat with the ignition switch on, yellow with black stripe is trigger ground when in the off position, and black with wht yellow stripe is fuel enhancer or choke solenoid....whichever your engine has, black is ground. I think i remembered all them correctly.

Hope your new switch is in working order.

 

[bsutravis]

Thanks Mark. It should be here on Wed of next week so I'll install it and go from there. I appreciate all the help.

 

[bsutravis]

Sorry for such a long delay... I haven't been able to get back at the Merc till this weekend and unfortunately I now have even more issues! I installed the "new" harness but I was troubled that one of the wires (Salmon colored) was cut and not connected to the key ignition. I looked at the wiring schematic and it looks like that salmon wire goes to no where on my motor? Anyway I installed the new ignition and turned it over and it cranked and cranked but never coughed. I pulled a plug and now I'm not even getting spark! I WAS getting spark to all plugs so I've got to assume it's something with this "new" harness or how it's wired at the key, or could it be the mystery salmon wire?

In my manual it shows how to trouble shoot Type III Ignitions but not Type II which is what I have on my '77.

I'm at a loss as to where to go from here!

 

[Chris1956]

The CDIElectronics web site has a troubleshooting guide for your motor. You should have a battery powered CDI ignition. You must have +12VDC on both the red wire on the switchbox and the adjacent white wire, to have spark. The salmon wire is unused, on your motor.

 

[bsutravis]

Thanks for the reply Chris...... just checked for voltage to the switchbox and I have nothing on the red and white switchbox wires. Thinking the harness I purchased isn't wired correctly? It was sold to me with a new ignition wired into a used harness so who knows if it's right. I'm off work tomorrow so I'll take it apart and check the wiring of that ignition switch.

 

[Chris1956]

The red wire on the switchbox should be connected to the battery power, under the motor cowl. The power on the white wire will come thru the ignition switch.

 

[bsutravis]

OK... My internal wiring harness inside the motor is only a few years old so it's all good. So if the red wire is battery power it should have constant power? The white wire will only have power when the key is on?

 

[jimmbo]

https://issuu.com/cdielectronics/docs/practical_ouboard_ignition_troubles
page 86. Your system is a Battery CD ignition