120 hp tracker only running on two cylinders

[bigmikev]

i have a 1998 120 hp tracker outboard motor, i noticed it wasn't running right so i put the muffs on it and started it in my yard. started and idled fine, i pulled number 1 spark plug wire off and it didn't make a difference in the idle of the motor, i did the same thing for number 2 and still didn't make a difference, i pulled number 3 and the motor bogged down and so did number 4. i then pulled out the spark plugs and both number 1 and 2 were wet with gas, i replaced all 4 plugs and checked it again and the same thing, i also checked the spark by putting a screw driver in the plug wire and holding it to ground and they both were sparking... what else can i check?? any help would be great!

 

[pnwboat]

Re: 120 hp tracker only running on two cylinders

First thing to check would be compression on all the cylinders. If you have good compression (around 120LBS), try moving the coil/CDM assy. around to see if the problem moves or stays with the same cylinders. If the problem moves, possible bad coil/CDM. If problem stays with the same cylinders, try checking the stator with an OHM meter. You should have 500 - 700 ohms between the Green/White and White/Green wires.

 

[bigmikev]

Re: 120 hp tracker only running on two cylinders

ok thanks, i will have to track down a compression tester to make that check. how do i move the coil/CDM assy. around and what should i look for in doing so? would it make a difference that it has a coil pack for each cylinder?

 

[pnwboat]

Re: 120 hp tracker only running on two cylinders

Since each cylinder has it's own CDM (coil pack), you can move them around to determine if one is bad. If the problem follows the CDM, then it's probably bad. If not, it's something that drives the CDM's. There are two bolts that hold each coil/CDM assy on the mounting plate and 1 modular connector. For example, swap the CDM's for #1 and #4 cylinders. If pulling #1 spark plug wire off now affects the idle, and pulling #4 off has no affect, then you probably have a bad CDM on #4. If this has no affect on the original problem, then you need to check elsewhere. The stator would be a good place to start.

Before you start trouble shooting the ignition system you need to verify compression.

 

[bigmikev]

Re: 120 hp tracker only running on two cylinders

i tested compression and it was between 145 psi and 155 psi on all 4 cylinders. i also tested the stator as stated and the reading was 720 ohms. i also swapped the cdi's from cylinder 2 and 3 to see if the problem moved as well but it didn't still have the same problem. so is the anything else i can try before taking it to a shop and missing out on this great boating weekend......

 

[fucawi]

Re: 120 hp tracker only running on two cylinders

Pulling off plug leads when the engine is running is a sure way to buggger your switchbox ...OK on 1960s cars but not on CDI systems

 

[bigmikev]

Re: 120 hp tracker only running on two cylinders

that is good to know... i hope i didn't mess it up even more. this problem has me stumped!!!

 

[pnwboat]

Re: 120 hp tracker only running on two cylinders

Don't loose faith, still a lot of simple relatively easy things to check. From you problem description, it's kind of difficult to determine if you have an ignition system problem, or a fuel system issue. Sounds like most of the major components in you ignition system are intact. The late 1990 Mercury CDM ignition systems are pretty reliable and much simpler than the earlier Prestolite CDI ignition systems. Take a look up under the flywheel and check to see that all six magnets are in place and intact, not broken. Also disconnect the two yellow leads between the stator and the regulator assy. If all of this checks out OK then I would take a look at the top carburetor. Does your primer bulb get firm after 4 or 5 squeezes? If the needle valve in the top carb is stuck open, you should see some gas come out of the small vent hole on the side of the carb. The last thing I would look at is the reed valve assy. under the top carburetor. It's actually located under the intake under the top carb. A broken reed valve petal will cause some strange symptoms.

 

[bigmikev]

Re: 120 hp tracker only running on two cylinders

what do i look for when i disconnect the two yellow leads?? also i have taken the top carb off and looked at the reeds with a flash light and all seem to be ok, keep in mind im not sure what i'm looking at but they were all there and didn't see any cracks in them. when i had the carb off i took it apart as far as i could and everything looked very clean,

 

[pnwboat]

Re: 120 hp tracker only running on two cylinders

When you take to two yellow leads off, see if that has any affect on the way the motor runs. Looking at the reeds through the opening after you remove the carburetor is not the best way to check them, but you should be able to see if any large pieces are missing from them. You will not be able to tell if they are lifted too far off of the reed block and sealing properly. Anyways, were you able to get a firm primer bulb after squeezing 4 or 5 times?

 

[bigmikev]

Re: 120 hp tracker only running on two cylinders

yes, after about 4 or 5 pumps on the bulb it get tight to where i can't pump it anymore.. if i remove the two yellow wires and it makes a difference what would that mean?