Help only running on one cylinder

[DaveAF]

Still trying to get the 88 50hp Evinrude running right (E50BECCS)

Today I went out to the marina and want to do some more trouble shooting. So using the OEM manual and a vohm meter want to check the electric coponents.

The coils are new, the power pack is new. So now I am trouble shooting the sensor coil and the charge coil. Both are with in specifications for resitance. I really could get a good reading when I tried to test the out put.

After I finally get the engine to start and run I started back to the basics. I pulled the plug wires starting on the bottom cylinder. Nothing happened it kept running. Pulled the top cylinder and the engine died. I swapped the spark plug wired and the the same, so I figured the plug wires are good. I then swapped the coils and the same.

What controls the time the coils fire? is it the power pack? or one of the sensors under the flywheel

Also if I have to pull the flywheel off, what is the best advice for breaking the center nut. I have a harmonic balancer and I am getting the Grade 8 bolts. I just cant figure out how to hold the flywheel while I loosen the nut.

I am needing help

 

[jay_merrill]

Re: Help only running on one cylinder

To loosen the flywheel nut, you can use an air impact gun if you have one. You will have to get a strap wrench eventually, however, because you need to use a torque wrench to reset the nut when you put the flywheel back on.

It sound like you have isolated the problem to the lower cylinder but do you know that the problem is in the ignition system. Did you use a spark gap tool to check? If not, you need to do that - they can be purchased at your local auto parts store for a few dollars. Also, if you haven't checked the compression on the motor yet, you need to. If the compression is very low on the bottom cylinder, pulling the top park plug wire could cause the motor to quit, just as if the bottom cylindeer wasn't getting park or fuel.

If the problem is ignition related, and is not the coil, spark plug or spark plug wire, I would say that the problem is either the sensor or the power pack. The fact that the power pack is new points the finger at the sensor. Is is not impossible, however, for a new part to be defective.

The sensor is the componet that directs voltage to the appropriate coil but the power pack plays part in that process. The power pack receives AC volatge from the stator, converts it to DC voltage and then stores it in a capacitor. There are switches in the power pack, which are triggered by the sensor, that then send voltage to the appropriate coil. That coil then steps up the voltage to about 30,000 volts to fire the spark plug.

 

[DaveAF]

Re: Help only running on one cylinder

Here is the compression numbers.


Cold Top Cylinder 135
Bottom Cylinder 140

After 30 min idle and run
Top Cylinder 120
Bottom Cylinder 130

I did check the spark with the spark plug and the spark on the top cylinder looked really yellow and the lower one was no spark at all.

I was searching a strap wrench and found a craftsman that looks like it would work.

 

[jay_merrill]

Re: Help only running on one cylinder

I'm thinking you have a sensor problem.

Here's something to try ... pull the spark plug wire on the top cylinder and set your bottom cylinder up for ignition testing by using a gap tool or pulling the plug and grounding it. Now pull the sensor wires (mark them if they are not already marked) and reinstall the number 1 sensor wire to the number two post on the input side of the power pack. Be sure that the top cylinder will not fire (wire pulled) because the objective is not to get the motor to run, and "hit" the starter. If you now see spark on the bottom plug, you will know that the number 2 switch in the power pack is functioning.