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TOPIC: 1969 Merc 1250 - No spark

1969 Merc 1250 - No spark 3 weeks 1 hour ago #140495

New to me boat but have no history but looks like not used for a long duration. Has twin 1250 Mercs - 1969. Motors look very original....and pretty clean. Got one running after replacing a few rotted wires....only ran for a short time as waiting for new impellers. Second one has no spark to all plugs. Checked all grounds, belt is good, disconnected mercury switch...still no joy. Have a working motor so exchanged coil, then switch box...still no spark. What next.....trigger? Is there a test for it? Looked around and don’t see any on eBay or a few suppliers I tried. Looks like CDI had them in the past but maybe no more?
Would appreciate some guidance/ knowledge.....thanks in advance.

Dave

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1969 Merc 1250 - No spark 2 weeks 6 days ago #140500

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Welcome aboard. You may get more Mercury people looking at this if you put this post under the Mercury Outpost forum. Good luck with finding the problem. Anything with twin 125 Mercs has to be good!

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Dr.Go!

1969 Merc 1250 - No spark 2 weeks 6 days ago #140503

Thanks...new to the site...my error.

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1969 Merc 1250 - No spark 2 weeks 6 days ago #140505

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Yes there is a test that bypasses the trigger in the distributor. See the attached diagram. It shows how you disconnect the (3) trigger wires from the distributor to the switch box. Then you jumper (2) terminals on that side and ground the 3rd. If you get spark out of the coil, the trigger is bad. One thing to keep in mind on this CDI system is that the red wire on the other side of the switchbox is always hot. The white wire is energized only when the key is turned to "ON" or "START".

So check for voltage at both of those terminals with the key on. If you have power there, then that's not the issue and you can proceed with the test.

The trigger assy in the 1250 distributor, fortunately, is replaceable. It's the same trigger used in various Mercruiser applications, so there are still some kicking around. Some 650 models used the same trigger, so that's a resource as well.

Here's a load of distributor parts on eBay for $75, including a trigger assy with bad wiring, but it looks like the internal wiring is still good and could have new lengths of wire spliced-in. If you were to do that, you'd want to be sure to solder the splice for good connection.

https:// www. ebay. com /itm/MERCURY-Kiekhaefer-1250-125HP-Outboard-DISTRIBUTOR-CAP-ROTOR-TRIGGER-393-1927A/264281094034?hash=item3d88617792:g:aqMAAOSwCtJaD2wx

HTH..........ed
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The following user(s) said Thank You: ykgoldstar

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1969 Merc 1250 - No spark 2 weeks 6 days ago #140507

Many thanks for the diagram - I will give that a try when I get back home.
I saw that trigger on eBay also....having not seen one before I wasn't sure if there was enough wire there to splice on some more...if you think there is I will consider it. Also saw a complete distributor for around $300, the seller says it was working when removed.
Can the trigger be replaced with the distributor in place? Have good mechanical abilities but not worked on a 1250 before....see four bolts that look like it might get to the trigger, but having not had one apart I am not sure. Is the trigger replaceable without upsetting the distributor settings?
Thanks again for the information...much appreciated.

Dave

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1969 Merc 1250 - No spark 2 weeks 6 days ago #140512

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Hi, Dave, you might want to check with the seller and maybe get a better pic of the internal wiring before committing. The trigger housing is indeed held in by those 4 bolts and will pull down for servicing. Be careful with the rotor assy; the shaft, rotor, and "chopper" disc are one integral unit and can't be separated without destroying them. The rotor shaft bearing is retained in the housing by the trigger. Once you pull the trigger's mounting screws, you can pull the trigger and rotor assy as one, until the rotor shaft bearing clears the housing. Then you can safely separate the rotor from the trigger.

Be very very careful when reassembling, you'll note how the rotor rides thru the pickup on the trigger. That little piece of pickup metal is quite fragile and should never be pried upon.

Here's an exploded view at marineengine.com:

www.marineengine.com/parts/mercury-outboard-parts/1250/2314956-thru-2839368/distributor-assembly-complete

Note that if you get everything back together in the same orientation as it came apart, it shouldn't affect the spark advance settings.

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

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1969 Merc 1250 - No spark 2 weeks 5 days ago #140517

Thanks for the info. Wasn't totally comfortable with that trigger and the seller could not guarantee it was in working condition. I found a complete "working" distributor on eBay and purchased it....am starting to collect some 1250 spares anyway as I plan to keep these motors going for a while. Now the wait...but am away from home anyway and it should be there when I return.
Would you recommend replacing the complete distributor and tackling the advance settings....or removing the parts off the donor and saving the advance settings? I did find a video on setting-up the distributor on an early 70's 6 cylinder...looks a little bit daunting for a first timer but not impossible.

Dave

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1969 Merc 1250 - No spark 2 weeks 4 days ago #140526

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On the 1250, there's no need to pull the entire distributor. If you remove those (4) 1/4-20 bolts holding the trigger housing, it slips right out of the upper distributor drive. Removing this, replacing the trigger, and reinstalling will not affect spark timing since the rotor shaft only goes in one way or is keyed such that you can't mess it up. .

You don't want to pull the distributor, that entails removing the flywheel and dist drive belt and is a lot more work. Plus you then do have to make sure you get the belt timing correct when you reinstall.

Later-model Distributor-Fired CDI's are different and you have to pull the entire distributor to replace the trigger, which is encapsulated into the distributor body and non-renewable. You have to buy a new dist body and that's almost $400 for a good CDI electronics version!

So, you're actually getting off a lot cheaper with this style of ignition, and easier to work on to boot. The dist. is a bit finicky to set up, but all you have to do is follow the manual and it's a piece of cake.

Have Fun!............ed

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1969 Merc 1250 - No spark 5 days 1 hour ago #140705

Distributor showed-up yesterday. I removed the trigger housing and installed it in place of the suspect one. One bolt tough to get at but got it done. Hooked up a battery, turned the key.....spark! Awesome.
Thank you ed-mc for your guidance....much appreciated. A lot closer now to getting the Power Cat on the water this year. I see I will need to replace the wiring in the future...but patched it up enough to get it on the water.
Haven’t figured out the trim/tilt yet....so far doesn’t seem to work.

Dave

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1969 Merc 1250 - No spark 5 days 1 hour ago #140706

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Yay, Having Spark is Good!

PT&T-wise, if you can get the trim motor to run, and the pump is good, the rams should go in-and-out. I've attached some service info and a wiring diagram for the single-solenoid system (most common on outboards), maybe that'll help.

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