Engine won't turn off/ 150 Johnson

[jawinn]

Okay, I searched postings on this subject last night and found a few things to check. Nothing holding the butterfly valves open and both "power packs?" are being grounded with the switch off. It seems like with the ignition off, one bank of cylinders continues to fire. Switch the key back on, and the thing revs like crazy. I had to choke it to kill it. Weird, most folks fuss with getting them to run, but no, I gotta be different. Can't shut mine off. Oh, and if I'm looking at the model number correctly, it's an '85 model year. Here's what I can read J15??LCOS. There is a dent in the plate between the 5 and the L that looks to be the width of 2 characters. Did I get that right? Any ideas on turning it off? I can see I'll be a regular here. Thanks in advance and sorry about the long post.

 

[Dhadley]

Re: Engine won't turn off/ 150 Johnson

It's probably 150 (well we know that!) and the next letter is probably a T.

If it won't shut off it'll have something to do with the kill circuit (black wire w/ yellow tracer) going to the pack that doesn't shut off.

When it runs will it idle or is it revving out of control?

 

[jawinn]

Re: Engine won't turn off/ 150 Johnson

I checked the yellow/black wire. It does ground when the ignition is turned off, so the packs are grounded, key off. I didn't give it a chance to rev too wildly before I switched the ignition off, but it got pretty high. When I switched the ignition off is when I noticed it seemed to run on one cylinder bank. Bad pack that's not grounding? I've had the boat out twice since I bought it and while it had the switching off problem, it didn't rev like that til I ran it at the house. Had the muff and hose hooked up.

 

[Molaker]

Re: Engine won't turn off/ 150 Johnson

It sounds something like a car engine that diesels when shut off due to raw fuel being dumped in along with a bit of carbon buildup. The over-revving could be the result of this fuel dump and an unloaded prop just taking off when you turn the key back on. Take a close look at the float settings and make sure the floats shut off good when full.

 

[emdsapmgr]

Re: Engine won't turn off/ 150 Johnson

If you are sure the ground wire is functioning properly to each pack, you may have a bad pack. While rare, it is not impossible for one pack to keep firing when the key is turned to off. I had your exact problem and installed a different pack. Fixed the problem.

 

[jawinn]

Re: Engine won't turn off/ 150 Johnson

Thank you. I'm gonna run it again and make sure which side is running on. As for dieseling, it actually sounds too smooth to be that. It's like a low idle. Is there a way to test the pack? Don't have a manual....yet.

 

[emdsapmgr]

Re: Engine won't turn off/ 150 Johnson

An easy way to check the pack is to switch it with the other. If the problem moves, you've got a pretty good idea...