Pulled spark plug wires

[brian3127]

I have a Johnson 40 hp model 40el75c
With the motor running I pull the top plug wire and the motor stalls out. When I pull the bottom plug the motor stays running. What does that mean. The first time I did it I pulled the top one and it stayed running. Each time I pull the wires I get shocked so there is spark at both plugs.

 

[boobie]

Re: Pulled spark plug wires

First place to start, what's the compression on it ??

 

[brian3127]

Re: Pulled spark plug wires

I'm borrowing a pressure gauge tomorrow if he brings it to work. Lets just say that the pressure is good what would the next thing to check then the next thing. I bought a tune up kit for it. I'm going to buy a flywheel puller tomorrow. I'm going to change all the parts out. My boat is at a slip so I won't be going back to it until I get out of work tomorrow. So if there are other thing to check please list them. Oh by the way when the motor is running it looks like an oil slick in the water.

 

[OptsyEagle]

Re: Pulled spark plug wires

First of all, get yourself a pair of insulated pliers for pulling spark plug boots. You are going to need them.

OK, so we know the bottom cylinder is not running or is very weak. I would now switch the spark plug boots to the alternate cylinders AND switch the clips that go to the coils. Now do the same boot pull test. Does the motor still only run when the bottom plug boot is pulled or has the problem now moved to the other cylinder.

If the problem moved to the other cylinder, then it is very likely that your problem is in the electronics. Probably a dirty point or bad point gap. Maybe a bad coil or condenser or lose wire. If the issue has stayed with the same cylinder, your problem is not under the flywheel or a coil. It is either bad compression, perhaps from a blown head gasket or scored cylinder or water in the cylinder, etc. It could also be a fouled spark plug.

Do the switch test and go from there.

 

[nwcove]

Re: Pulled spark plug wires

have a look at the plugs......both look the same, or is the top plug soaked with gas and bottom plug dry? if so, try swapping the bottom coil to the top to see if the problem follows the coil.
as boobie said, compression test first, before spending any $$$ throwing parts at it without knowing what direction yer throwing!!

 

[brian3127]

Re: Pulled spark plug wires

What are the cylinders suppose to be at and what are they supposed to be between each other ?

 

[boobie]

Re: Pulled spark plug wires

Post back with what you get and you'll get an answer. The rule of thumb is no more than 10 % variation.

 

[brian3127]

Re: Pulled spark plug wires

i got the compression guage today so weather permitting i will hopefull have a answer today.

 

[Boss Hawg]

Re: Pulled spark plug wires

Had the same situation on my 110 a couple weeks ago-
Took all the advice you've been given & everthing pointed to one cly not firing-
Boobie suggested i clean my carbs- I did- problem solved.

 

[brian3127]

Re: Pulled spark plug wires

Ok did a lot of checks. Yesterday I put new points ant set them to.020 and I put new condensers on. Today I finally got the compression gauge and that read top cylinder about 124 lbs and the bottom read about 118. Then I bought a spark tester and both cylinders will jump a half inch gap with a blue spark.

 

[brian3127]

Re: Pulled spark plug wires

This is 40el75c Johnson I have spark plugs
Champion
UL81C
Are these the correct ones

 

[nwcove]

Re: Pulled spark plug wires

compression is good. im seeing the factory recommended plug as Champion L82C.

 

[brian3127]

Re: Pulled spark plug wires

This is what it does when it's running sometimes it stalls quicker

 

[brian3127]

Re: Pulled spark plug wires

any takers

 

[jlh42581]

Re: Pulled spark plug wires

Do me a favor, open up your fuel pump, have a look and see if ethenol ate your check valves. If so, order a rebuild kit or a new pump. The kit is about half the price of the pump, I recently had a very similar issue. If I were to do it again id just buy the whole new pump.

Ill bet you have a problem there or a torn diaphragm

 

[brian3127]

Re: Pulled spark plug wires

i did that last week. All of the plasitc parts and springs and gaskets are in good shape.

 

[fishfeatures]

Re: Pulled spark plug wires

maybe you've already done this but i can't see mention of it , swap around the ignition coils that the spark leads are attached to. if the problem stills remains with the same cylinder after the pulling the spark plug leads off, then the issue isn't electrical but probably fuel related.

 

[OptsyEagle]

Re: Pulled spark plug wires

Brian, have you confirmed that both cylinders are running yet? If I recall the bottom cylinder was not running previously. Did you do the "plug boot and clip" swap test to see if the problem moved to the next cylinder or stayed on the bottom?

The video just shows a motor shutting down. We need a little more info.

 

[brian3127]

Re: Pulled spark plug wires

i for got to check that i will do that check today after work if the rain ever stops. i will post results as soon as ii get them

 

[OptsyEagle]

Re: Pulled spark plug wires

Just so you know, when you report that a cylinder is not firing, the next thing you want to do is figure out "why" it is not firing. Since it can be electrical (points, coils, condensers, wires, spark plugs) or mechanical (compression, seals) the swap test is the very next test to run. It eliminates one of those variables.

Forget about fuel (carb, pump, tank and fuel lines) because in almost all fuel issues, both cylinders would be effected. In your case it is only one.