Need help 1989 100hp johnson GT100

duffg130

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Hi,

Recently purchased a 1989 GT 100 johnson. The guy I bought it from said he took the boat out to get it ready to sell and at 2500rpms the motor shut down. No alarms, no noises, just stopped. I am by no means a mechanic but he suggested trying a new power pack and or stator. I replaced both and it fired up. Sounded like it was misfiring. I turned it off and am unable to get it started again. After trying for several minutes I get a puddle of oil in the driveway coming from the prop area. I checked for spark and was only getting spark in the 2 left cylinders. I moved the spark plug wires and got the same results. I swapped the wires coming from the power pack to the coils (took the ones from the left and put on right side), which is odd because I had them the same way as the one i took off. Well once i did that, I had spark in all four cylinders. Doesn't seem to make sense. Nonetheless, it still doesn't start. Any help would be appreciated. Remember, I'm not a mechanic but I can swap parts and wires. Also, compression is good in all four cylinders. I am going to post 2 short videos and a picture of the oil puddle. Thanks
 

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duffg130

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It is not. So I disconnected the VRO and set up a small 50:1 tank. Still didn't start. I was having no or intermittent spark. I put the old powerbpack on and it fired up. I will say that I had no idea that pushing the key in activated the primer solenoid. So when I was continuing to push it in and turn the key I was flooding the hell out of it. Not to mention all the oil in my driveway. Yes, I feel like and idiot but the yamahas i have don't have that feature. I plan on hooking up the VRO again because I don't think anything is wrong with it. It definitely seems to be running rough but I'll see how it runs after I hook up the VRO again. As for for the power pack, I had to cut the kill switch connector and use the old one because they wouldn't fit. So now I am going to have a difficult time getting a replacement from the company.
 

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racerone

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The motor is running.-----But not running on all I believe.---Best to post compression numbers here.
 

duffg130

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All were between 105-110. I can run another test on Friday and list compression on each one. I just forget. The first time I started it after I replaced the stator it sounded pretty good. It was idling high but it hadn't warmed up yet. I put the video. Thanks
 

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duffg130

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I replaced the coil packs and the motor is running good. I still plan to hook up the VRO this week. Now I am having an issue with the kill switch. I fired the motor up in the barrel and there was a ton of smoke/exhaust. Even though the water inlets were submerged, I thought maybe it needed more water. I turned the key off and the motor didn't turn off. Pulled the kill cord and it still didn't turn off. Ran to get the hose and continued to spray it in the barrel. I finally pulled the fuel line and let it run out of gas. I did have to cut the kill switch connector on the power pack and splice a different connector but those connectors are tight. The kill red pull cord and button look in tack as well. Any suggestions?
 

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duffg130

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Any suggestions on my last post would be much appreciated. The black wire from the power pack is grounded and the black and yellow wire is also in tact. Could disconnecting the VRO have any effect on the motor not turning off? For the VRO, I disconnected the 3 prong wire and the two black electrical wire for the system. One was grounded to the block. Thanks
 

havoc_squad

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VRO has nothing to do with kill circuit

This outboard like most (never assume) operate with ignition circuit as normally open (engine running) that connects to ground.

Which means when you want to turn it off, it grounds the black/yellow wire to ground.

Unplug the kill circuit connector to the power pack and check first with multimeter that there is NO voltage on kill circuit harness connector with key on engine off.

If there is voltage, the power pack will get fried/damgaed.

If no voltage from key on engine off (good), turn key off and test for continuity from kill circuit connector on harness to ground.

If continuity and you have ground washer on the power pack ground wire bolted to the block, it has to be a bad power pack.

A simple test is using an insulated probe with engine running connected to ground and ground out the black/yellow connector on power pack.

If ignition still on, it's a bad power pack.
 

racerone

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Some will argue-----These motors are nearly world famous for broken piston rings.----With 105 PSI on my tester the motor would be coming apart I think.-----Easy to inspect pistons / ring via the 4 wee bypass covers on the side of the block.
 

duffg130

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Thanks. I will check that later. I'll post the results. I appreciate
VRO has nothing to do with kill circuit

This outboard like most (never assume) operate with ignition circuit as normally open (engine running) that connects to ground.

Which means when you want to turn it off, it grounds the black/yellow wire to ground.

Unplug the kill circuit connector to the power pack and check first with multimeter that there is NO voltage on kill circuit harness connector with key on engine off.

If there is voltage, the power pack will get fried/damgaed.

If no voltage from key on engine off (good), turn key off and test for continuity from kill circuit connector on harness to ground.

If continuity and you have ground washer on the power pack ground wire bolted to the block, it has to be a bad power pack.

A simple test is using an insulated probe with engine running connected to ground and ground out the black/yellow connector on power pack.

If ignition still on, it's a bad power pack.
So with the engine running, I clipped the alligator clip from my tester to the black ground on the power pack. I then touched the probe to the black and yellow wire coming from the power pack. The engine shuts off. So I guess the power pack is good?. The odd part part is, when I fired it up a couple weeks ago after I replaced the stator the key worked fine and shut it off.
 

duffg130

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Some will argue-----These motors are nearly world famous for broken piston rings.----With 105 PSI on my tester the motor would be coming apart I think.-----Easy to inspect pistons / ring via the 4 wee bypass covers on the side of the block.
I checked the compression today with the engine warm. 105 in all 4. I don't really know how to inspect the pistons/rings.
 

havoc_squad

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I checked the compression today with the engine warm. 105 in all 4. I don't really know how to inspect the pistons/rings.

As racer said, you can remove the bypass cover and gain access to piston & rings and remove spark plugs to turn crank to get access to piston.

What people do other than looking for obvious damage is take a wide thick flat head screwdriver and carfefully check that the rings have spring tension by pressing on them lightly.

As for me, I want to see how much % of air loss you get doing a leak down test.

You can have a crappy low PSI compression test gauge, but there's not much disputing leak down results done right.

I believe any clyinder with more than 10% leak needs to be fixed.
 

duffg130

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As racer said, you can remove the bypass cover and gain access to piston & rings and remove spark plugs to turn crank to get access to piston.

What people do other than looking for obvious damage is take a wide thick flat head screwdriver and carfefully check that the rings have spring tension by pressing on them lightly.

As for me, I want to see how much % of air loss you get doing a leak down test.

You can have a crappy low PSI compression test gauge, but there's not much disputing leak down results done right.

I believe any clyinder with more than 10% leak needs to be fixed.
Thanks. Any more thoughts on the motor not turning off? I did the probe test with engine running and it shuts down.
 

havoc_squad

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Thanks. Any more thoughts on the motor not turning off? I did the probe test with engine running and it shuts down.
If it happens again test the kill circuit when it happens as what you did. If you're that worried about it happening again, replace with OEM and buy the aphenol connectors and tool to fix the bandaid change.
 

duffg130

Seaman
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Messages
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If it happens again test the kill circuit when it happens as what you did. If you're that worried about it happening again, replace with OEM and buy the aphenol connectors and tool to fix the bandaid change.
Not sure what you mean. Every time I turn the motor on, it won't turn off. The power pack is OEM (according to part number for my motor) but the one connector wasn't compatible.
 

duffg130

Seaman
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Aug 20, 2015
Messages
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If it happens again test the kill circuit when it happens as what you did. If you're that worried about it happening again, replace with OEM and buy the aphenol connectors and tool to fix the bandaid change.
What if I cut the connectors off both black and yellow wires and spliced the wires together? I took apart the control box and the wires connected to the ignition switch look good. I guess my next step is a new ignition switch.
 
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