TOPIC: merc 800 no spark (help)

just got back to the computer and read the doc's reply to my no spark problem. and yes i do need help in checking out the 3 items that will cause a no spark condition. a dead trigger (dist), a dead switch box, and a dead coil. i should have all the tools and test equipment, as i have been a auto mech. for the last 40 years. now working on outboards is greek to me. so i need to be pointed in the right direction . i will need to know were these parts are mounted and what values i'am looking for. if i can get this motor running with out going broke i want to. it sure looks good on my crestliner. thanks in advance for any info. frog. This email address is being protected from spambots. You need JavaScript enabled to view it. p/s if any of you need help on gm cars and trucks, drop me a line and i'll be happy to help.

Frog,
I will be e-mailing you a large PDF file that goes into great detail on thesting various ignitions.
You'll want to review pages 57-60.

Here is a quick way to test that might solve the mystery.
It was originally written by Clams Canino.
Thom

MERCURY BATTERY-POWERED CDI TEST
FOR DISTRIBUTOR MODELS, Courtesy of Clams Canino

This test is for the 332-2986 switchbox used from 1967-1978 on all the inlines.

This test assumes your coil is good (most all are).

DISCONNCT BATTERY

1. Turn off ignion
2. Disconnect all 3 wires on the distributor side of the switchbox.
3. Remove the HV lead from the coil to the center cap (remember it unscrews
from cap)
4. Reconnect that HV center lead to the COIL side only.
5. Position that HV lead about about 3/8" from ground (block, shrouds etc)
and find a way to hold it there.
6. Jumper the brown and white terminals on the dist. side of the switchbox
together.

RECONNECT BATTERRY

7. Check that you have +12 V at red terminal.
8. Turn on ignition and verify +12V at white terminal (on red terminal side)
9. Touch the black terminal to ground - unit should cause spark each time
you touch ground.

If that passes and it won't fire at all, suspect the trigger.

AND,...
More good words from Dean at John’s Old Merc site:

Merc 950SS with points electronic ign:

“To test that unit is really simple. Remove both wires from dist side of switch box remove coil lead from coil and unscrew from cap and hold next to ground be sure to have it gapped, oh by the way this does not have a trigger it has 2 sets of points, take a test lead alligator clips both ends, attach one to the single terminal turn on key and tap other end to ground every time it contacts it should spark if not switch box is bad, also do not panic a 3 terminal dist side box will work by jumping across black and white and attach both wires to brown. Good luck”

went to test out the ign system and figured to check comp first. the starter sol. just buzzed, so that is bad . then tryed to jump starter an that did not spin. so no comp test done. getting discourged, so if any of you guys need any parts off of a 1970 merc 800 i'am going to parts it out. i will run an ad in glassifieds also. just trying to get my investment back, have controls with. want 100.00 for all. thanks to the doc for his help. frog

Sorry to hear about the motor.

If the controls work for a 77 Merc 500 I am very interested. Round plug-in harness into the side of the motor. I have resurected this old girl by bringing several motors together and she is running fine but I just need some controls with a harness and key.

Shoot me an email with your number if interested.
This email address is being protected from spambots. You need JavaScript enabled to view it.

Thanks,
Tim

barnfinder, the controls for my 800 does not look like my 500. i tryed e-mailing you and it would not go thru. frog