1988 Johnson GT 150 ignition problem

[ffountain]

My engine will not cut off when I turn the key off or pull the lanyard from the kill switch. I do notice a difference in the sound of the engine when I turn the key off (sounds like it is struggling to run) but it doesn't shut off. Any advice on trouble shooting the ingnition system?

 

[HighTrim]

Re: 1988 Johnson GT 150 ignition problem

Welcome to iboats.

Your kill circuit is probably disconnected or shorted. It is the black wire with the yellow stripe.

 

[ffountain]

Re: 1988 Johnson GT 150 ignition problem

Thanks Chris,

I'll take a look.

Fred

 

[HighTrim]

Re: 1988 Johnson GT 150 ignition problem

Good luck, check the key switch along with the power packs.

 

[emdsapmgr]

Re: 1988 Johnson GT 150 ignition problem

The ignition switch and black wire/yellow tracer are two good starting points. I had the identical problem on my V6 with twin packs. When the key switch was turned off, the engine sounded different, but continued to run. Changed out one of the two packs and no more problem. My guess is that my defective pack was incorrectly continuing to transfering current, even though the black/yellow wire was trying to short out the packs.

 

[ffountain]

Re: 1988 Johnson GT 150 ignition problem

Did some checking. No shorts in the black/ yellow wire. Should I have 12volts at the switch between the red+ (ign) and the black/yellow with the switch off? I also have the same 12volts with the kill switch lanyard removed.

 

[HighTrim]

Re: 1988 Johnson GT 150 ignition problem

This link describes it better than I can.

http://continuouswave.com/whaler/reference/ignitionSwitch.html

 

[ffountain]

Re: 1988 Johnson GT 150 ignition problem

Thanks for the link. My wiring checks out but I don't have a diagram of the wiring for my engine. I have the original owners manual but it has no repair info or diagrams. Are there any of the aftermarket books that you guys prefer or links that might give me a wiring diagram?

 

[emdsapmgr]

Re: 1988 Johnson GT 150 ignition problem

You need an original factory manual to get the colored wire, cooling and trim diagrams. They are still available from the original printer, Ken Cook Co, in Milwaukee. I'd call them to order. The last one I got from them was a photocopy, and the fold-out colored diagrams in the back were all black and white. Useless. So, ask them if the copy you need is still avail with the colored diagrams. If not, look for another source for an original copy, perhaps ebay...

 

[ffountain]

Re: 1988 Johnson GT 150 ignition problem

Good luck, check the key switch along with the power packs.

So how do I check the power packs?

 

[Gary H NC]

Re: 1988 Johnson GT 150 ignition problem

Here is an original manual on Ebay...Item #110212833704

 

[ffountain]

Re: 1988 Johnson GT 150 ignition problem

Here is an original manual on Ebay...Item #110212833704

Thanks.

It's on the way. Any suggestions until it arrives?

 

[ffountain]

Re: 1988 Johnson GT 150 ignition problem

Good luck, check the key switch along with the power packs.

Got my book yesterday. Thanks again Gary.

Did some reading and the book says the same thing (check the key switch along with the power packs). Goes into great detail on checking the key switch and kill switch but not on checking the power packs without lots of special equipment. It also tells you how to check for output problems. I don't think I have a problem with output because my motor starts and runs fine (just won't cut off). Is this something that is beyond the scope of the home mechanic and something that only a dealer can check? For now I plan to go back and check my key and kill switch in more depth and also check and clean all grounds. According to the book I could have continuity on the wires but not have the correct ohms.

 

[ezeke]

Re: 1988 Johnson GT 150 ignition problem

The black and yellow kill wires work by simply grounding the power packs. If you ground them to the engine block, they will shut down the corresponding cylinders instantly, because there will be no fire. If they do not shut down, the powerpacks are bad.

If any voltage at all reached the power packs through the black and yellow wires the powerpacks are probably damaged.

The black and yellow wire has weak points at the big red engine plug, at the bend in the harness at the transom, and at the ignition switch.

 

[ffountain]

Re: 1988 Johnson GT 150 ignition problem

The black and yellow kill wires work by simply grounding the power packs. If you ground them to the engine block, they will shut down the corresponding cylinders instantly, because there will be no fire. If they do not shut down, the powerpacks are bad.

If any voltage at all reached the power packs through the black and yellow wires the powerpacks are probably damaged.

The black and yellow wire has weak points at the big red engine plug, at the bend in the harness at the transom, and at the ignition switch.

Thanks. So if I unplug the blk/yel kill wires at the connectors on the engine and ground them directly to the engine block it should shut down. Will I be able to start the engine with the blk/yel wires disconnected at the engine or will I need to start the engine then disconnect? Will it harm anything to perform this one pack at a time?

 

[ezeke]

Re: 1988 Johnson GT 150 ignition problem

You can start the engine with the black and yellow wires disconnected, but not grounded of course.

The ignition switch has a black ground wire that comes from the engine block through the harness to the smaller M terminal on the switch. When you turn the ignition switch to Off the switch connects the other M terminal which has the black and yellow wire to the smaller M terminal and grounds out the powerpack.

When you ground the powerpack at the engine block by grounding the black and yellow wire, you just shorten the run. You should be able to shut down one powerpack at a time, but the engine may stall.

The first diagram shows what the switch does when you have the key turned off. The second diagram shows what happens in the run position B (battery) connected to A. So, in the run position the engine is free and on its own and can only be stopped by grounding the powerpacks, running out of fuel or being flooded (You could pull the spark plug wires, if you like pain).

 

[ffountain]

Re: 1988 Johnson GT 150 ignition problem

You can start the engine with the black and yellow wires disconnected, but not grounded of course.

The ignition switch has a black ground wire that comes from the engine block through the harness to the smaller M terminal on the switch. When you turn the ignition switch to Off the switch connects the other M terminal which has the black and yellow wire to the smaller M terminal and grounds out the powerpack.

When you ground the powerpack at the engine block by grounding the black and yellow wire, you just shorten the run. You should be able to shut down one powerpack at a time, but the engine may stall.

The first diagram shows the what the switch does when you have the key turned off. The second diagram shows what happens in the run position B (battery) connected to A. So, in the run position the engine is free and on its own and can only be stopped by grounding the powerpacks, running out of fuel or being flooded (You could pull the spark plug wires, if you like pain).

Thanks. I'll give it a check. If I find I have a bad powerpack, can I replace just the bad one or do you recommend replacing both?

 

[ezeke]

Re: 1988 Johnson GT 150 ignition problem

Just what is bad should be replaced. I think you will find that you have a wiring problem.

 

[ffountain]

Re: 1988 Johnson GT 150 ignition problem

Just what is bad should be replaced. I think you will find that you have a wiring problem.

Thanks ezeke.

Powerpacks are fine. Started to troubleshoot wiring but my son just had to go Bass fishing. Perfect conditions here in Georgia. Couldn't stop him. He's just like me when I was his age. I did narrow my search to the wiring between the big red connector at the engine and the controls. To repair a short in that part of the harness I'll have to split the insulation enclosing all the wires. Would I be better off to buy a replacement harness? If so, where would I have to go to purchase a new replacement? Don't think I would want to go with a used harness.

 

[ezeke]

Re: 1988 Johnson GT 150 ignition problem

Before you tear into the harness or buy one, do a few more tests and see if you can narrow it down.

Disconnect the battery.

First, make sure that the circuit is either really open/bad. Take an ohmmeter and connect the two contacts to the points marked in blue on the thumbnail below on the big red plug leading to the remote control. Make sure that the ignition switch is in OFF position. If the circuit is closed then the circuit is OK if it is open it is not.

If the circuit shows closed, then turn the key to RUN and see if the circuit shows open.

Now if that works out the harness would be OK and so would the switch.
If it does not, then you need to test the ignition switch circuit.

Ignition Switch Test
With the switch in OFF, put your ohmmeter leads on both M posts. The circuit should read closed. When you turn the switch to RUN, the circuit should read open. If the M circuit does not read closed when the switch is turned to OFF, The switch is bad.

Ground Wire Test.
Run a length of wire from one of your ohmmeter leads to the engine and connect it to the Red plug at the point marked as BLACK. Connect the other ohmmeter lead to the small M post with the black wire on the ignition switch. The circuit should read closed. If it does not, the black ground wire has a break.

Kill Wire Test
Run a length of wire from one of your ohmmeter leads to the Big Red Plug at the point marked BLACK YELLOW and connect the other ohmmeter lead to the large M on the ignition switch. The circuit should read closed. If it does not, the black and yellow wire has a break.​