Mercury 850 s/n 4232599 help. Crank but not start and no spark

[pacmanusmc]

Hi guys, I just bought a used 1974 Stryker with a mercury 850 thunderbolt. After checking everything I found out along the line of ownership some moron used home interior wire in the electrical system. Before I drop so much money into this I need to determine if it's a money pit. Other than that there is no spark. Disclosure; I have a basic knowledge of mechanics but no experience on outboard, I am learning as I go through internet searches and were able to conduct the tests. Some tests I've done revealed the following so:

1) There are compression on all 4 cylinders. 149, 150,150,149 (so that's good)
2) Fuel pump worked (primed bulb and disconnected line after fuel pump saw fuel shoot out of of line leading to carb.
3) Checked ignition coil (all good there)

Being that the fuel is fresh and pump is good, there's compression and I have to say the problem is electrical. So this is where I'm at. Since there was no spark I pulled the distributor cap and tested all the way to the ignition coil and found out the everything below. Can someone help address my questions below and/or tell me what I should do next?
1) Ignition coil is good (checked ohms)
2) distributor cap is corroded ( can I clean it out with electrical cleaner or someone can suggest something else?)
3) Rotor is corroded (is there a way to clean that without replacing it is since molded into the whole distributor assembly?)
4) Checked continuity of spark plug wires and lead from ignition coil and have continuity.
5) Want to check the resistance but need to know what my range is. (couldn't find the range anywhere for my model motor)
6) If the spark plug wires are bad Can I replace the spark plugs with blockard 440 7 mm or msd 8.5 mm plug wires if I make my own plug wires?

I really appreciate all the help guys.

_Pac

 

[Chris1956]

Spark plug wires are stranded stainless steel. Resistance is futile (actually zero).

The switchbox must have +12VDC on the red and adjacent white terminals. The white terminal voltage originates at the keyswitch. The red voltage is always hot.

The CDI Electronics website has a test for everything but the trigger. It requires that the wiring is good and the coil is good. I would test the spark at the coil until you get it there, then reconnect the distributor.

Wires unscrew from the distributor cap. New wires can be had on the web for $6 or so each. Search for "yellow tigertails".

A new Dist. cap is $100 or more, so clean yours up with cloth and find sandpaper.

 

[pacmanusmc]

Thanks Chris, I was cleaning the distributor cap and dropped it and it crack. I was going to clean it up and reinstall but now it seems I have to purchase a new distributor cap. Anyone have suggestions on where I should look or a used or an aftermarket cap at a decent price? The 850 I have is 4 cyls. Thanks -Pac

 

[Faztbullet]

Put it back together to see if you get spark,if not your going spend more than a $100 to fix it. Check to see if trigger belt is broke. Apply 12V to red and wht at switchbox and jump starter solenid, if you got spark advance forward with repairs, if not look for different motor as the pit gets deeper....

 

[pacmanusmc]

Anything special I have to do when reinstalling the distributor cap? I didn't put Mark's on the assembly to line it up the way I had it prior to installing. Thanks.

 

[racerone]

Most caps will only go on one way.----Inspect it for a spot that only goes in one place.

 

[pacmanusmc]

Ok.... update. I JB WELDED the distributor cap yesterday and today I sanded it down with my dremmel and reinstalled. Checked for spark and got spark on all 4 cylinders. So I sprayed sea foam, primed the bulb and applied the choke wih my hand and it fired over. Had it running with the remote starter switch. So will try and find the dristritbutor now. Next question is on this button. I'm assuming this is the kill switch. It is not one of the ones with a lanyard so I disconnected it. Now I want to put it back and don't remember how it was hooked up. I remember it being was wired to the white on the switch box. It has one green and one yellow wire. Can someone have any ideas on how I can work a new kill switch with a lanyard in case I go overboard? Thanks.

 

[Faztbullet]

You have the cap and lanyard for it???

 

[pacmanusmc]

Faztbullet, the previous owner did not give me anything else with the boat so no. So am I correct and that is the kill switch? I need to rewire it back on the switch box or at least install a kill switch with the lanyard. So need help wiring it back or installing the new switch. Thanks!

 

[The Force power]

Faztbullet, the previous owner did not give me anything else with the boat so no. So am I correct and that is the kill switch? I need to rewire it back on the switch box or at least install a kill switch with the lanyard. So need help wiring it back or installing the new switch. Thanks!

If that is indeed the kill-switch; just buy a new one & install in a good place.
If that is NOT the Kill-switch but horn or chock-switch; you have to run a set of wires from the new switch to inside the motor, one to ground & the other on the ignition-box on the terminal that grounds the ignition.

 

[Chris1956]

The kill switch would be wired to the brown terminal on the switchbox, where the mercury switch is wired, not where the distributor is wired.

I would skip it for now, as I consider it optional. IMO, Kill lanyards are great for boats where you could be pitched out or fall down, while in operation. If your boat does not have that potential, you likely don't need one.