Ignition Trouble with 1971 merc 135

[Doug Redinger]

I recently acquired an old 16' fiberform with a Merc 1350 inline 6 on it and I can't get the engine to fire. Checked for spark with an inductive timing light and could not get the light to flash. Connected the timing light on the coil output wire and still no flash. I am thinking it has to be either the distributor , the coil , or the switch box. I am hoping to narrow it down using the process of elimination. I have an old 1967 Merc 950SS that runs great and was hoping to swap out the 3 components one at a time onto the 1971 Merc 1350. The coil and the switchbox appear to be the same. The distributor looks the same but I think there were some changes between the 1967 and 1971 distributors. The max advance timing on the 1967 says 36.5 degrees while the 1971 shows max advance at 23 degrees so they must trigger differently. Would these substitutions work. I just want to narrow my search and would not leave these components installed on the 1350 other than to test it and to get it to fire up.

 

[emckelvy]

Re: Ignition Trouble with 1971 merc 135

I'd bet on the trigger, the rate of failure on triggers is much higher than that of CDI switchboxes.

Here's a test which should help you confirm the problem:

"MERCURY BATTERY-POWERED CDI TEST FOR DISTRIBUTOR MODELS

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

This test assumes your coil is good (problems with CDI coils are rare).

DISCONNECT BATTERY

1. Turn off ignition;

2. Disconnect all 3 distributor wires on the Port side of the switchbox (and the ?mercury switch? if present);

3. Remove the HV lead from the ign coil to the center of the dist. cap (remember it unplugs from the coil and unscrews from the cap);

4. Reconnect the HV lead to the COIL only;

5. Position the free end of the HV lead approx. 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 to each other.

RECONNECT BATTERY

7. Check that you have +12V at the red terminal (even with the ign off);

8. Turn on ignition and verify +12V at the white terminal (same side as the red terminal);

9. Ground the black terminal on the distributor side of the switchbox - this should cause a spark each time you touch ground.

If you get spark with the distributor bypassed, and it won't fire with the distributor connected, the trigger is bad and the entire distributor housing assy must be replaced.

If you get no spark using the test, the switchbox is probably bad. In that case, be sure to check for correct power on the switchbox, check all connections, and check the coil's resistance to make sure it's OK."

BTW if your 950's ign has 2 wires coming out of the distributor, connecting to a single terminal on the switchbox, it won't work with the later-style CDI ign. You need a 3-wire distributor to fire the newer CDI switchboxes.

If your 950 does have a 3-wire trigger, it'll fire the 1350's switchbox, but the above test completely bypasses the distributor anyway.

If your 1350's ign system fires with the distributor bypassed for the test, it's a 99.9% certainty that the trigger assy is bad. I've seen new trigger assy's on eBay around $275.

HTH.............ed

 

[Doug Redinger]

Re: Ignition Trouble with 1971 merc 135

Thank You so very much Ed for the great information. Very detailed and to the point!! I will follow your procedure this weekend when the snow melts and let you know what I find. Thanks again for your help. I love the great information and experience that can be found at this site.

Doug

 

[emckelvy]

Re: Ignition Trouble with 1971 merc 135

Doug, happy to be of some help. The 1350 brings back fond memories, in the '80's I picked up a 16' Sidewinder-SS and found a dead 1350 Merc cheap. Replaced the busted crank with one out of a 1250 and threw that on the 'Winder. What a screamer that motor was! Drank a lot of fuel but back then it was cheap!

The ign died one summer day, I found the snap ring holding in the lower rotor bearing in the distributor had rusted & grenaded, and took out the trigger. Luckily the local outboard boneyard had a complete working distributor for $50 and I was back on the water in no time.

You won't find 'em that cheap nowadays unless you're really lucky! I keep scrounging the Craigslist for parts and every once in a while you come upon a Phantom Black treasure that makes it all worthwhile!

I'm sure you'll be very surprised at the 1350's performance on that 16' Fiberform. Hold onto your hat!

G'luck with your repairs.........ed

 

[Doug Redinger]

Re: Ignition Trouble with 1971 merc 135

Ed Thanks again for your great advice!!! I used your test procedure to test my distributor and it worked great!!! Got a nice big fat blue spark every time I grounded the black terminal. Now I have to pull the distributor and see what I can find. I am counting on a bad trigger as you suggested. The distributor cap is smeared with silicone rubber and appears to have some cracks so I may be replacing the cap too. Was hoping to get lucky and find an easy inexpensive fix, but I dought I will be that lucky!!!
I am really looking forward to getting the boat back in running condition. A 135 h.p. motor seems like quite a bit for that little old 16' fiberform so she ought to fly!!!

Doug