TOPIC: 1977 mercury 1150 6 cyl no spark still!

My dad purchased a 1977 Starcraft with a Mercury 1150 on it in a non-running state. I found that the old owner broke the distributor cap, left it off, which corroded the rotor. I purchasde those and installed them, only to find, that the motor has no spark at the plugs.

I've performed the switch box test/coil test, and I get spark at the coil. For a while I was getting spark at the coil during cranking, but not anymore.

I cleaned the motor ground and ohmed the ground to the battery (also cleaned). I rewired most of the motor, I still have no fire at the plugs (only when I turn the key on or off on occasion). Then I disconnected everything running to the motor, except the hot and the ground battery connections. I removed the mercury tilt swith.

I also place a jumper on the two hot positions on the switch box. Then Jumpered across the starter solenoid, to turn the motor over.

If I do the switch box and coil test, I get a hot spark on the coil. If I put the coil wire back in the distributor, place the crank to TDC,I get a spark to the #1 plug.

I believe that the trigger is not functioning. How do I test the trigger? Or am I missing something?

Larry

There's not much of a way to actually test the trigger except to hook it up to a known functioning ignition system.

Which you have, in a sense. By doing the Merc CDI test where you completely bypass the distributor, from what you have stated you are getting spark every time you ground the black terminal on the distributor side of the switchbox (with all 3 wires on the distributor disconnected).

Therefore, you have proven that the trigger is bad. The CDI Electronics replacement trigger is the most reliable replacement. You may be able to find the part on eBay cheaper than at most marine parts stores online.

Plan on a full rebuild of your distributor, including new upper & lower ball bearings (unless they are perfect), and a new snap ring. Replacement of the snap ring is mandatory, as the old ones can become brittle with age, break and destroy the trigger & other parts in the distributor.

The CDI P/N for the trigger is 134-3736 and has gone up astronomically since the last time I looked for one!!!!

I found one for ONLY $349.95 at this site:

bpi.ebasicpower.com/shop/index.php?main_page=product_info&products_id=2774

$386.71 at Marineengine.com:

www.marineengine.com/newparts/part_details.php?pnum=CDI134-3736

Given they're so expensive, you might want to check your local Craigslist to see if there are any parts motors kicking around. Heck, you might find a complete motor with a good distributor for less than the cost of a new trigger assy!!!

HTH & G'luck...........ed

Im going through this same thing with a mercury 800. Basically, with ignition problems on these motors, what is usually done is to buy and replace the entire "power pack". That is, the cdi box, distributor with trigger, and the stator. All of them. Plus, there are usually a bunch of corroded wires that will need replaced, or the power pack will burn out again.

I think most folks try to get away with replacing 1 piece at a time, but end up replacing all of them to get it running again. Thats me...

My merc800 is a fast motor, swings a big prop, but its going to be a 1000 dollar fix at the end of the summer!

I had purchased a used distributor off of ebqy, however it arrived damaged. I was waiting for the seller to straighten the mess out, however I got fed up and installed it to check spark. I managed to get spark through to the plugs.

I then removed it and tore both distributors apart and built one out of the two of them.I reinstalled it and still have spark.

Today I will install the new rectifier, and replace the wires on the stator. Hopefully fire it one of these days.

Just a reminder,...
If you are 'hot-wiring' direct to the starter or solenoid without an external wiring harness attached to the battery, be sure and either dis-connect and tape off the two yellow stator wires at the rectifier, or connect a jumper wire between the rectifier's + terminal and the + post of the battery to avoid ruining your rectifier.
doc