Controller/Kill switch/plug gap questions

I have a 1981 90hp Johnson model #J90TLCIM. I also have the Seloc repair manual and the Clymer shop manual. Funny thing...Clymer says spark plug gap is 0.040" and Seloc says 0.030". I believe its 0.030" for L77J4 plugs? I I'm using replacement plugs L77JC4.

Seloc does not go into any detail on the emergency ignition kill switch that I can see, or in the wiring diagram but the Clymer does. It looks like the kill switch was used in 1982 and later for the 90hp. My question here is do I have the right controller and what is the 1/8" hole in the lower front portion for? When in neutral there is a plate that slides just behind the housing and when in gear, forward or reverse, the plate moves away. Just curious. Must be inside parts moving around. Thats not a kill switch is it?

On this controller I believe when you push in the key it activates the primer solenoid to inject fuel thru the crankcase into the cylinder. Well...it doesn't work but when I apply 12V to the solenoid(purple/white) I can hear the plunger pull in. If I find the Ign switch checks out, except for this issue, can I just mount a momentary contact push button switch somewhere instead of replacing the entire switch. Using manual operation every time everytime I start is a hassel cause I have to pull the cowling.

I'm just getting ready to fire it up and wanted to make sure my thinking was correct first. Anything special about the Tach to be used? All I have is old OMC tach for pre 1969 motors.

I'm not absolutely certain this controller was used for this motor. The previous owner had a 70hp and switched to a 90hp in the same year so the when I got this motor home I discovered the wiring harness had been cut out and is missing about 10 feet. Not a problem all the wires matched up.

Thanks in advance.

Re: Controller/Kill switch/plug gap questions

Gap the plugs to .030

The factory service manual is well worth its weight in gold

What is the position of the red handle on the fuel solenoid ?

Re: Controller/Kill switch/plug gap questions

Fuel solenoid = primer solenoid? Its in the run position pointing back toward the #1 cylinder. Black handle though.

Plugs I replaced had electrode wear with gaps greater than 0.040" I thought 0.030" was correct but was surprised to see the Chymer shop manual say 0.040"

Just tested compression. 115,110,112,115. Strong spark arched over 1/2" to ground on all plug wires. Should get a spark tester and I have both analog and digital multimeter but I haven't gone thru the troubleshoting steps yet. If I have good spark what does that tell me about the ignition components. I'm more familiar with pre 1969 motors and will have to get familar with CD ignition systems.

Cranking but not starting. Checked plugs after test and they are bone dry. Should I continue with the ignition troubelshooting or eliminate fuel problems first. Bulb pumps up hard.

Re: Controller/Kill switch/plug gap questions

It sounds like you have a fuel delivery issue, compression and spark tests are good. Spray some pre mixed fuel into the carb throats and see if it will now fire, if only briefly. That will determine that you have fuel system issues.

What is your starting procedure?

Re: Controller/Kill switch/plug gap questions

Since the primer solenoid is not working with the key switch I'm either flipping the lever to manual and squezing the bulb several times, you can hear and feel the fuel squirt, then flip to run position and squeze bulb till hard. Or I am applying 12V to solenoid in 4 to 6 short incraments. Move the warm up lever on controllerto start position then start cranking.

Re: Controller/Kill switch/plug gap questions

Results from premix spray in carb throats.

I tried this before and again with the same results. Big ole single gunshot backfire out the exhaust without temporary fire. My next thought was either timing or possibly the plug wires were wrong. So I just now went to check my wiring again and wiring diagrams for both manuals.... and now I'm completely confused and its no wonder.

The Seloc manual had the orange-orange/blue wires pointing to the same wire on the port(red circle) side so I looked how it was wired on other side and made an assumption how it should go.

Then I checked the Clymer manual diagram for 1981 but it didn't designate the ignition coil numbers...so I flipped the page to 1982 diagram and the only difference I can see is it has the kill switch but it did have the coil numbers designations. So I thought it would be the same as the 1981 diagram. Could be wrong there. So I scanned the manuals and hopefully you can understand my confusion or at least show me where my thought process went wrong.

So what I'm hoping is that the plug wires are reversed on both sides. I'm thinking the Seloc diagram is correct...well at least on the starboard side cause I'm guessing on the port side. It shows the orange/blue should be onthe 3 and 4 cylindar not the 1 and 2. That would put the ignition coil right next to the cylindar and plug that it goes to which makes more sense in my mind. My pic shows how it is currently wired. Unfortunately this is how I got this beast of a motor and if they are backwards I hope I haven't caused any other damage and if I have I should go and drop this motor on this guys head. Actually I should just go out and reverse the wires and see what happens but that shotgun backfire sound makes me and my dogs want to jump out of our skin.

Thanks...keeping my fingers crossed as to this being a big portion of why it won't run. I know it will also need the carb rebuilt, lower unit service, connections cleaned and some vac hoses replaced to name a few.

Re: Controller/Kill switch/plug gap questions

Here are the Clymer manual scans. Hope you can read them. Don't know why they didn't show up in last post....maybe file size was too big.

More info. This is how I see the the cylinder designation from looking at the back

2 1
4 3

o/b = orange blue

Re: Controller/Kill switch/plug gap questions

OK.....I just had a hammer land on my head. Should have read what was on the white sticker on the #3 cylinder plug wire. It says what type of plugs to use and the word "Top" on it!!!!! Must go on the #1 cylinder.

I'll give it another crank in the morning.

Re: Controller/Kill switch/plug gap questions

let us know what you find

Re: Controller/Kill switch/plug gap questions

Fired right up Chris!!!!:redface: Did do a squirt or three with the manual primer solenoid and no squirt down the carb throat but boy was it loud, quick and sounded fast (idle) so I quickly lowered the Start/Fast idle lever and shut it down. I imagine it will be less loud when its off the muffs, in a body of water and the air silencer cover is back on. I think I'll go thru the carb synchronization steps next befor I fire it up again.

Boy its no wonder I was confused with the wiring diagram discrepencies. I spent alot of time getting to this point with lots of doubts and fustrations but I will say I've learned quite a bit about this motor and with the good compression I think its got great potential. I'll get back to it later. Right now my 1960 really Fat 75 needs some loving before I replace it with this 90hp Johnson.

Thanks Chris for your support

Re: Controller/Kill switch/plug gap questions

Good job! Best way to learn is to just get in there and do it eh.

Should be much quieter on the water, good luck with it.