Engine Stop Button

[Hutch9900]

So, my engine stop button isn't working apparently. Does anyone have a diagram for how this is wired? I assume there is some kind of solenoid but not sure which one and where to find it.

 

[MYTraveler]

Depends a lot on the engine, but most require that button connect the incoming wire either to ground, or to power.

 

[Hutch9900]

Sorry should note this is for my FL120.

 

[Comodave]

On my last boat we had SP225s. The stop button failed in the energized position so the engine wouldn’t start. I replaced it with a horn button that was a momentary switch. Worked fine. It just energizes the stop solenoid.

 

[jleonard]

Here's the wiring diagram I have for the Lehman 120. Hope it helps.

 

[rwidman]

On some engines, there is a solenoid that is energized to allow fuel flow and on others, the solenoid is energized (momentarily) to stop fuel flow and stop the engine.

It's important to know which system you have before you begin troubleshooting.

On the first, turning the key energizes the solenoid and allows fuel to flow. You should have 12 volts at the solenoid when the key is set to "run".

On the second, you should have 12 volts at the solenoid when the stop switch is activated. This is what I have.

Troubleshooting is as follows:

You need 12 volts at the switch (measured to ground or negative).

When you press or turn the switch, you should have 12 volts at the other terminal of the switch.

When you press or turn the switch, you should have 12 volts at the actual solenoid.

Disconnect the wire from the solenoid and measure the resistance from that terminal to ground. You should have a few ohms (five or so). If there is no resistance (infinity), the solenoid is open (burned out).

On my engine, everything checked out but the engine wouldn't stop. I suspected that the solenoid was being prevented from moving for some physical reason. I tried to remove it but stuff was in the way and fuel was leaking out. I screwed it back in, and reconnected the wire, figuring I would work on it another day.

It has been working fine ever since and this would be a hundred or more engine shutdowns and a couple years.

 

[Hutch9900]

Here's the wiring diagram I have for the Lehman 120. Hope it helps.

Very helpful thank you Mr. Leonard!

 

[Hutch9900]

Thank you for the step by step troubleshooting. I will work on this again when I get back to the lake.

 

[warfdog]

On the FL120 the stop lever is activated by a solenoid mounted next to the injection pump. It has single connection for power (to stop the motor).

 

[backinblue]

Slightly off topic but related.....I can stop my engine by pushing the stop button or turning off the ignition key. I assume either one turns off the fuel pump, but is one prefered for some reason? I think the manual suggests using the stop button. Engine is Yanmar 6LPA-STP.

 

[psneeld]

Many engines are stopped quite differently.

Lehmans originally had a solenoid linked to the fuel control that required 12V to activate and pull a lever on the fuel pump to shut down.

The trick is, on older boats, ya never know how they are wired now.

The stop button should be a simple momentary switch with a positive feed on one terminal, with the other sending 12V to the solenoid near the fuel pump.

How you want to wire it, keep it the same, or convert to manual is up to you.

 

[RT Firefly]

Greetings,
Not applicable in this case but the stop on our Lehmans is a pull cable. Purely mechanical. No solenoids or electrics. That way from the Cheoy Lee factory.

 

[rwidman]

Greetings,
Not applicable in this case but the stop on our Lehmans is a pull cable. Purely mechanical. No solenoids or electrics. That way from the Cheoy Lee factory.

That is a bit inconvenient to operate from a flybridge. I suppose it's possible to rig two pull cables but the flybridge cable would be long and convoluted.

If your engine has a stop solenoid, there's a good chance it also has a manual lever that can be pulled to stop the engine if the solenoid system fails. Mine does.

It's a good idea to find that lever and try it out before you really need it.

 

[psneeld]

If you run throttle and shift mechanical cables.....why would mechanical engine shutdowns be difficult ( especially on larger vessels and/or with good cable runs)? The shutdown for a Lehman could run right alongside the throttle cable.

Bridge to lower helm, piggyback and run to engine...just like throttle.

 

[BruceK]

Greetings,
Not applicable in this case but the stop on our Lehmans is a pull cable. Purely mechanical. No solenoids or electrics. That way from the Cheoy Lee factory.

Lehmans on my IG36 were a mechanical pull cable too. Simple and effective. This new fangled electrical set up clearly has problems.

 

[catalinajack]

My Lehman 120s are stopped with a momentary button that actuates a solenoid that pulls in a lever that shuts off the fuel supply. Occasionally, one of the buttons does not work but, when it does, I have to push down hard and a bit long to get it to work. I have even had to go into the engine room to manually cut of the fuel supply. The botton needs to be replaced as I have verified that I have 12VDC at the button.

 

[jleonard]

Just remembered....last season when I sold my boat, the engine did not shut down (when the surveyor was there if course).
I manually shut it down.
The problem was that the stop button and solenoid were functioning, but the lever on the pump somehow got loose so the lever wasn't travelling enough to shut the engine down.
I had to first loosen then adjust the lever. Took a few tries, the adjustment is very touchy.

 

[brmoney]

Put a meter on the solenoid to make sure that it is not dragging the voltage down when energized. I have seen on more than one occasion a loose positive or negative connection (not even in the same zipcode as the solenoid) will not give the solenoid enough pull to shut the engine down. Once found the culprit connection on a battery to engine negative cable to the block on the opposite side of the engine.

 

[Xlantic]

It could also be a mechanical problem with the solenoid or the linkage to the fuel pump.

For example something has come loose in the linkage or some dirt has gone in around the solenoid plunger.

 

[FF]

IF the engine has a lever to operate the engine stop, a push pull cable is the simplest to operate , or repair.

 

[Hutch9900]

Just remembered....last season when I sold my boat, the engine did not shut down (when the surveyor was there if course).
I manually shut it down.
The problem was that the stop button and solenoid were functioning, but the lever on the pump somehow got loose so the lever wasn't travelling enough to shut the engine down.
I had to first loosen then adjust the lever. Took a few tries, the adjustment is very touchy.

After speaking with the previous owner, I believe this to be the issue. He said he had the same problem before as well and that it was very sensitive in adjustment.

 

[SteveK]

That is a bit inconvenient to operate from a flybridge. I suppose it's possible to rig two pull cables but the flybridge cable would be long and convoluted.

If your engine has a stop solenoid, there's a good chance it also has a manual lever that can be pulled to stop the engine if the solenoid system fails. Mine does.

It's a good idea to find that lever and try it out before you really need it.

Not sure why it is inconvenient to go down to shut off. After a run I shut off below after listening for any change in a smooth running engine. Had to go down to deploy anchor or tie up at dock. Engines allowed to cool down for a few minutes while that is done.
I also have pull cables for cold start only at lower helm.

 

[jgwinks]

The stops on the Detroits in the tour boat I run sometimes hang up and don't stop the engine. So we go down and pull them by hand and maybe give them a shot of lube spray. We have to go down to the ER anyway to switch power and shut off the generator. Could be just a little corrosion on the shaft binding it up.

 

[koliver]

Not sure why it is inconvenient to go down to shut off. After a run I shut off below after listening for any change in a smooth running engine. Had to go down to deploy anchor or tie p at dock. Engines allowed to cool down for a few minutes while that is done.
I also have pull cables for cold start only at lower helm.

Though my boat is equipped with stop buttons up top, I don't use them. My usual operating procedure is to dock from up top, tie up properly, on the dock, while the Admiral shuts off the engines from the wheelhouse, where the alarms operate to indicate no oil pressure and is the only location from which those alarms can be shut off.