Force 120, idles good, miss/hesitation/smoking as rpms go up, video inside. Help!

phampau

Cadet
Joined
May 2, 2015
Messages
7
Here is an update to my previous thread with different issues now...http://forums.iboats.com/forum/engi...orce-120-idle-issues-other-issues-help-please

So the motor seems to misfire as the rpm's go up as seen in this video... https://www.youtube.com/watch?v=3OLA6U3pHUY
At 1:11 you start to hear it and as rpms go up, it gets progressively worse at 1:24, at 1:42 is about wot and it is blowing tons of smoke....

Here is a bit more info on what we have done....
1. Separate gas tank to eliminate bad gas
2. Changed inline fuel filter
3. Put a spark tester on each cylinder and as the rpm's go up and it misses, the spark gets weaker and weaker, at full throttle, it is showing no spark going through the tester, this is on all 4 cylinders.
4. Spark plugs come out pretty black/rich. Around both the outside and electrode
5. Pulling the plug for coils 1 and 2 while the motor is running has a slight change in engine stumbling/sound...pulling the plug for coil 3 almost kills the engine but not quite, pulling the plug for coil 4 shuts the motor off.
6. The lower end is in a 50 gallon bucket of water so there is probably a little more load than on muffs, but not as much as being in the water.

We do not have a DVA adapter to troubleshoot the ignition system yet but we are thinking maybe the trigger or stator is on the way out...

Your thoughts/help would be greatly appreciated. Thanks, Paul
 

Jiggz

Captain
Joined
Oct 23, 2009
Messages
3,817
Double check the timing first before anything else. Make sure it is set to 28 degrees static. Thereafter, verify the air fuel mixture screws are set at 1 1/8~ 1 1/4 turn out from lightly seated. Ensure both carbs throttles open in synch. Conduct a test with the air covers off and watch the blow back from the carbs to see if there is a lot of fuel being spitted out while running the engine especially at idle or mid speed. With too much blowback from the carbs, that is an indication of bad reeds.

If problem persists, switch the CDM between 1 & 2 and 3 & 4 and then do the plug coil pull test again. Post your results.
 

HotTommy

Lieutenant Junior Grade
Joined
Mar 15, 2013
Messages
1,025
Paul,
My 1993 Force 150 is similar to your engine except for 5 cylinders instead of 4. I bought it in need of a rebuild and struggled for a long while to get it running right because, like you, I didn't have all the tools needed to troubleshoot the entire ignition system. By the time it was over I had replaced the flywheel (magnets had come loose), the stator (likely damaged by the flailing magnets), the coils, spark plug wires, the converter/CD and finally the switchbox Your best bet is to start with the advice above. Then, if you don't have the right tools and there are no reliable mechanics nearby and readily available, your only other choice is to start replacing components, starting with the cheapest ones. You might be better off investing in a DVA adapter, but you'll not likely need it again after you get this engine running right. ... BTW, I bought new replacement parts from aftermarket suppliers that were much less expensive than Mercury brand products. So far, so good.
 

phampau

Cadet
Joined
May 2, 2015
Messages
7
Thanks for the Help Jiggz and Hot tommy,

I will double check the timing on the next day i'm able to work on it (when checking timing the 1st time, it was in neutral at WOT and i'm reading it has to be in gear so i will do that next). I also haven't synced the carb's throttle plates so that will be next in line. I will also swap the cdm's around to see if any are bad. HotTommy, I think you are right and I might just have to invest in a DVA adapter if i'm going to troubleshoot the ignition system. It will be much cheaper than just replacing components! Thanks again for the help! Paul
 
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