J15RLCOB 15HP shuts off at idle throttle

I'm sure that this has been gone over, but I could not find the information using search.

I have a 1985 15HP Johnson J15RLCOB that I use as a kicker on my sailboat. I would really like to make the setup safer. Right now, the engine quits if I turn the tiller throttle to the minimum position. Since I often sail alone, I really don't like it when I am trying to bring the boat into my Branford River stake mooring and the motor stops.

I have tried adjusting the idle speed knob on the left side of the motor to max, and the difference is clear, but it still shuts down. I adjusted the mixture, but that did not help, either.

What do I do next? I have changed the plugs and they are gapped correctly. Due to other issues last summer, there are new coils and a new power pack. Spark is good. The motor starts well and runs strong.

One thing that seems unusual is that the tiller throttle mark does not go past the middle of the start icon, the "double circles". The tiller gears seem correctly meshed, but something might be wrong, there. I don't have another motor to compare it to.

I would like to add remote control to this motor, but I want to solve the idle issue, first.

Thanks, everyone.

Re: J15RLCOB 15HP shuts off at idle throttle

My best guess would be your carb. is dirty. Specifically your low speed jet. I would get a carb. kit and clean the carb. very thoroughly and a compressed air chaser before putting in the new parts. Best of luck. Rick.

Re: J15RLCOB 15HP shuts off at idle throttle

Rick, that certainly won't hurt, but I should say that I had the carb rebuilt last August after my object lesson on how water is not a fuel. I'm going forward with your suggestion, but I'm wondering if there is a low speed adjustment that I should also be doing. Seems I read, somewhere, that some folks like to set up the throttle to shut down and some like it to go to idle. Have you heard anything like that?

Re: J15RLCOB 15HP shuts off at idle throttle

Do you have a service manual. If you do you should do a linc and sync after you clean the carb. The common consensious would be that you should change your fuel lines from the tank to the carb. as the old rubber does not like the new ethanol gas and will break down on the inside. The new lines should be ethanol approved. Rick.

Re: J15RLCOB 15HP shuts off at idle throttle

OEM manual is on order. Fuel hose is brand new OMC ethanol resistant. Maybe I should be changing the hoses in the motor, too. Didn't think of that. Thanks.

Re: J15RLCOB 15HP shuts off at idle throttle

I cleaned the carb and replaced almost all the parts in the kit. It looked very clean (it was rebuilt last August by Brewer's Bruce & Johnson Marina). Set the float level. Blew out whatever passages I could access. Replaced the spark plugs, while I was at it. They were fouled (wet and black), but the electrodes were square.

No difference. Motor still shuts off when I move the tiller throttle slower than the "shift" marks.

Compression is just above 90. Power pack and coils new, last September.

Manual is still not here. What could I try, next? I won't be able to play until next weekend, so I have a moment to get materials together.

Re: J15RLCOB 15HP shuts off at idle throttle

According to the parts breakdown I was looking at you have an adjustable low speed jet. Have you adjusted it since the carb was rebuilt? Normally if the adjustment is to lean, screwed in, the engine will spit. You did not say anything about spitting, so maybe it is rich,turned out to far. Try turning it in, lean it out, till it spits and then back out 1/4 to 1/2 turn. Make the adjustment slowly.

Re: J15RLCOB 15HP shuts off at idle throttle

On the port side you should have and idle adjustment knob. It is what I call cruise control and is very useful for slow trolling. Try turning it in a little and your throttle will bump up to it and you an adjust your engine idle with it. Like I say it is put there for trolling but works as a throttle stop as well. When you get the manual I would recommend a linc and sync as well. Rick.

Re: J15RLCOB 15HP shuts off at idle throttle

Oh. Yes. I guess I assumed that this part would be somewhat obvious, as I had to adjust the mixture just to get it to start. I spent about 10 minutes tweaking. Turned the adjuster 1/8 of a turn and waited about 10 seconds to see what effect it would have. Got it to a point where it wanted to quit and then opened it up 1/2 a turn. Runs nice, but still cannot get the throttle any lower than the shift marks. Even a little bit will stall it right out. Makes for some hairy maneuvering when coming into my stake (2 piling) mooring in a tidal river.

I took a look at the gears at the pivot of the tiller, but they are correctly meshed.

Of course, after all that fooling around, the engine was nice and warm. I'm hoping that it will start when it is cold...

Re: J15RLCOB 15HP shuts off at idle throttle

If you backed the slow idle screw and you can't get it to go passed shift on the controls you may have slipped the gears.

http://www.sschapterpsa.com/ramblings/Johnson_9.9_troubleshooting.htm

look at point 8 for a pic.

Re: J15RLCOB 15HP shuts off at idle throttle

Rick. said:

On the port side you should have and idle adjustment knob. It is what I call cruise control and is very useful for slow trolling. Try turning it in a little and your throttle will bump up to it and you an adjust your engine idle with it. Like I say it is put there for trolling but works as a throttle stop as well. When you get the manual I would recommend a linc and sync as well. Rick.

Click to expand...

Gizmobreaker: I'm not talking about the slow speed needle. I'm talking about the Idle Adjustment Knob. See here. Rick.
http://shop2.evinrude.com/ext/index.aspx?s1=5ee10f7b60604e63364dc4cbb44c947c

Re: J15RLCOB 15HP shuts off at idle throttle

Or look at the knob on my motor.


http://www.kingpin.ca/gallery2/main.php?g2_itemId=2854

Re: J15RLCOB 15HP shuts off at idle throttle

You most likely have two very common issues.

1. The marks on the twisp grip don't line up, they rarly do on an older motor and I don't think most people even look at them, I know I don't.

2. The idle adjustment knob doesn't work, its another very common problem with this design, a great idea, but not very durable.

This was discussed here in great detail about a year ago, with a complete description of how to repair it. Try doing a search and see what comes up.

Re: J15RLCOB 15HP shuts off at idle throttle

Oops! Rick, I was replying to Daviet's message; yours had not shown up at the time. Sorry to add more confusion. My Idle Adjustment Knob seems to work fine. When you turn the knob, the nylon(?) slide moves and adjusts the amount of travel of the throttle. Not enough adjustment to help, though.

Bktheking, thanks for the links to your photos and to LeeRoy's Ramblings. His Troubleshooting page and his Normal Maintenance page are my bible. That's partly why I am so confused about this issue.

Ondarvr, the throttle, itself, rotates normally over the full range. The problem is that the engine stops if I rotate it too far clockwise, which is very dangerous while I am in the narrow river, trying to tie up the boat. I'm trying to get close to the pilings and I have to jump to the motor and hope that it will start quickly, before I hit another boat or a piling. My sailboat has no brakes! As I mentioned, above, the Idle Adjustment Knob seems to work perfectly, with plenty of travel, but there is not enough adjustment to help me. I would estimate that I can only use 1/3 of the rotation before it quits, so the nylon slide would have to be at least another inch longer.

I'm beginning to think that I need to find a working motor to look at. I don't suppose anyone is in the New York City, or Branford, CT, areas and wouldn't mind a visit... Of course, if anyone knows of a traveling outboard mechanic in the area, that isn't too expensive, that might be a real help, too.

Gratefully,
Marty

Re: J15RLCOB 15HP shuts off at idle throttle

Carb still might be the issue, what if you pump the fuel bulb while turning it to the lowest setting, wondering if the fuel pump is weak?

Re: J15RLCOB 15HP shuts off at idle throttle

That's a thought. I'm not sure what you want me to do, though. Should I pump the bulb with the motor running or stopped? Set the throttle at the absolute lowest setting or at the lowest setting where it will still run? What should I be looking for? Should I just replace the pump, to be sure?

Re: J15RLCOB 15HP shuts off at idle throttle

I'm not a fan of replacing parts for the sake of replacing them, that can get expensive. Run the motor as you normally would, when you turn the throttle down to where you know it shuts down or right before, try pumping the bulb as you twist the throttle. If it continues running then your pump is weak.

Re: J15RLCOB 15HP shuts off at idle throttle

If like you said, it starts easily and runs well, then there most likely isn't a problem with the carb being dirty.

When you hold the twist grip in the correct position, will it hold an idle well?

Is the problem that it just won?t stay running at less than 1/3 throttle setting (according to the twist grip), but runs well otherwise?

A yes to these indicates a linkage issue, very common with this setup.

If it won?t idle down at all, just dies at an RPM that it should be able to run at, then it could be dirty, or have other problems.

The idle adjuster not being able to travel far enough to set the idle correctly is discussed in the other thread I talked about.

Re: J15RLCOB 15HP shuts off at idle throttle

Disclaimer: I cannot get to the motor until this weekend.

When the throttle is left at the Shift marks, it will hold idle. I have not put a tach on it, but I can put my ancient automotive tach and dwell on it and also a rubber-tipped analog hand tachometer. Maybe the manual will arrive by then, so I will know what rpms to look for! The throttle does not move on it's own.

When at idle, it just barely moves my 6500 pound sailboat. This is fine. I just want the throttle to go fully clockwise without stopping the motor.

The throttle marks are not perfectly set - if you move it full counter-clockwise, the arrow just barely makes it to the Start icon. If you move it fully clockwise, it goes much further than the Shift marks; perhaps 2/3 of the rotation is past this position.

I searched for the other thread and found some, but I cannot find a way to set it far enough. Perhaps I need to adjust the rotation, so that the stop will work where I need it.

Ondarvr, based on your criteria, this sounds like a linkage problem. Does that refer to the gears at the pivot of the tiller, or something else?

Thanks, everyone, for your patience and advice.
Marty

Re: J15RLCOB 15HP shuts off at idle throttle

It sounds like your gears are out at the tiller handle, I have one sitting in garage that is exacltly like this, I will have to reset it up when I get the powerhead back on, the teeth are brass and they will wear and jump over time.