Merc 85hp 1973

[MTRebman]

Ok, I am completely new to boating. On a whim I bought a 1973 caravelle for what I feel was a good price. It has a 85hp 4cyl motor, from the serial number it is the original motor. A few questions before I go and screw something up. First is this a 50:1 mix fuel? And I have no spark on the motor, It simply will not start, It cranks fine. I read online and 1 article says it is the trigger. If so, how do I test it? Any help would be appreciated.

 

[CharlieB]

Never ASSUME anything as there is NO RETURN on electrical parts.

Does the control have a safety shut off switch? A missing lanyard holding the switch ON or the ignition won't fire.

Troubleshooting any ignition problem you need the factory service manual or the CDI Troubleshooting Guide
http://www.cdielectronics.com/wp-content/uploads/2013/08/Troubleshooting-Guide-Inside-Pages.pdf
The guide has detailed instructions how to test and determine what part is at fault.

 

[Yegboats]

The stator, distributor, rotor are all NLA. Switchbox, ignition coil are available but on the pricey side.

 

[Chris1956]

You must have +12VDC on the white wire and adjacent red wire on the switchbox, in order to have spark on that model. At this point in it's life, the wiring harness may be bad, leading to a no-spark condition.

 

[MTRebman]

Two things. Yes the lanyard is missing. But the switch is in he on position. It does not spring back to the off position which I thought was weird. Maybe the switch was replaced with a simple toggle? I check on that later and get back to you. I know the harness is all taped up from various repairs but as far as I can tell electronically it is fine. I plan on rebuilding or replacing it at a later time.

 

[merc850]

See if this diagram helps, there's no factory lanyard kill switch.

 

[MTRebman]

See if this diagram helps, there's no factory lanyard kill switch.

This is a 75, mine is a 73 and mine has a switch below the key.

 

[merc850]

Only thing different is the coil shape; someone has altered (maybe the switch is for the choke) or replaced the control box: it should be this one, I would replace any bad wires even if it means buying a new harness(es)
a fire onboard can be fatal!

 

[MTRebman]

That definately is not my control. I tried the toggle switch in the other position and I still get no fire. I am going to start tracing my electrical and see if I have power where I am suppossed to have power and go from there. Ill try and get more pictures later of what my controls look like.

The best I have found for a new harness is 280 bucks, all I can say is OUCH!!!!

 

[MTRebman]

Here is what I have. I tested the red and white wire as suggested. I have 12v on both the red and the white (white while key is on). I do not have 12v out to the distributor on the other side of the switch box, only tested while key was on, not when cranking.

https://gyazo.com/6655595f967f593edab292487ada8839
https://gyazo.com/3463373e9f5e94df3093f6b99c66bacf
https://gyazo.com/c54154da106d1ea8d61ab9493632a38d
https://gyazo.com/e2c114d9b6d588aeccb14442c8e8ca1d
https://gyazo.com/2f3a1070d6a58ec59e44e6dd8cfce6ce
https://gyazo.com/f53e2c94fe0ec08e683d19d8850069f8

 

[Chris1956]

You are not supposed to have voltage to the distributor or coil, when the key is on. The ignition system pulses the coil with ~300V, when the trigger tells it to. It is hard to read those pulses on a voltmeter.

The CDIElectronics web site describes a test for the switchbox, ignition wiring and coil. You should run it to eliminate those components. The test will tell you if the trigger is bad.

 

[MTRebman]

You are not supposed to have voltage to the distributor or coil, when the key is on. The ignition system pulses the coil with ~300V, when the trigger tells it to. It is hard to read those pulses on a voltmeter.

The CDIElectronics web site describes a test for the switchbox, ignition wiring and coil. You should run it to eliminate those components. The test will tell you if the trigger is bad.

I did follow their test after I posted that comment. It has been traced down to a bad trigger. I am wondering now, how do I get the distributor off to replace that part? There are 3 nuts holding the distributor to the engine. I can get to 2 of them fairly easily. The 3rd it is too close the the wide part of the distributor for a socket, and a wrench hits everything leaving no room to turn it. Any suggesstions?

 

[Chris1956]

Gee, if I remember correctly (been a long time) there are 3 nuts recessed into the distributor casting on top of the motor. Removal of those allows the distributor to drop straight down.

 

[MTRebman]

Gee, if I remember correctly (been a long time) there are 3 nuts recessed into the distributor casting on top of the motor. Removal of those allows the distributor to drop straight down.

Ill look at that this weekend. I hope you are right because otherwise I dont see how it comes off.

 

[Chris1956]

Scratch that. I just looked at the motor. It has 3 nuts holding the dist on, as you had described. I do not remember having any trouble getting them off. Maybe try a box wrench or offset open end wrench.

 

[MTRebman]

I dont have an offset open end. Im kinda at a stand still until I figure out how to get this thing off.. Its tempting that when I do get it off to switch the bolts out for allen head bolts so I can put them in from the bottom up and leave the nuts in the tops side.

 

[MTRebman]

YEAH!!! It's off. Not sure how i am going to get it back on though... anyone got a teardown on this distributor?

 

[MTRebman]

Ok people. Is there some sort of conversion kit available?