Fitting a fuel valve solenoid instead of a pull to stop system..

[FionaJC]

I have a Perkins 4107 diesel. To stop the engine I pull a lever on the injector pump. To make it easier I have a linear servo which when activated feeds out and a spring pulls the lever to the "RUN" position. When I turn the ignition off the linear activator pulls the wire back in and the engine stops. As seen below.


My old engine had a solenoid in the injector which needed to be energized for fuel to flow.


Can I fit a solenoid valve between the fuel pump and the injector pump to do the same job to start the engine? One person said yes and another said the engine will race away, then stop and need re-bleeding.


The reason I am asking is that the linear servo keeps getting corroded and needs replacing every 2-3 seasons. Also China keep sending me the wrong one that pulls when energised and not pushes.

[tkeithlu]

If I am following you correctly, your solenoid is activated to allow fuel flow while the engine is running. That means that the solenoid is in continuous use, when it may be intended for intermittant use, which if true could be the reason you are burning them out.

Then, your new goal. If your goal is to stop the fuel flow in the same way the lever on the injector pump operates, so you have a push button at the helm to shut down the engine, why not just attach the solenoid to the lever? If not that, then I don't see a reason that stopping the fuel flow between the two pumps would be a problem - that's what the throttle on my two diesels does, and it does not interfere with the prime. In either case, wire the solenoid such that briefly activating it shuts down the engine, not such that it has to be activated to run.

Go forward, this should not be a difficult project.

[a64pilot]

You don’t want to be starving a pump for flow, it’s not good on the HP pump. The reason why there is a low pressure pump that feeds the HP pump is that it is bad for it to have to suck fuel, and of course by shutting off the fuel flow your making it pull a hard vacuum.

It will not run away, but it’s entirely possible that it could get air in the system, and if not air then fuel vapor from a low pressure, aka cavitation.

Why not just install a manual cable at the helm, or of you want a shut off solenoid, buy a better quality one, an easy source is a Yanmar one, they seem to last for decades.

[FionaJC]

Originally Posted by tkeithlu

If I am following you correctly, your solenoid is activated to allow fuel flow while the engine is running. That means that the solenoid is in continuous use, when it may be intended for intermittant use, which if true could be the reason you are burning them out. .

The solenoid is attached to the lever now.


A linear actuator is not a standard solenoid. It is a motor with a worm gear pulling in a cable or paying it out. It is open to the elements and cannot be sealed. They are rusting and seizing. A standard solenoid in an injector is powered all the time without issue.



I am not burning them out. They hit the limit switch and stop. No current draw. The solenoid pulls the lever in the manner you say to stop by applying a voltage to the third wire to pull it back like a stop lever. Which I have as an emergency stop. Thats what I want to get away from.


the question is. If I fit a flow valve before the injector will this stop the engine without needing to be bled again.
.

[FionaJC]

Originally Posted by a64pilot

You don’t want to be starving a pump for flow, it’s not good on the HP pump.

That was my worry. Its actually a linear actuator not a solenoid. These have a 12v motor a worm gear and two limit switches. Its the motor/worm gear that seizes.

A manual cable will need to be 5 metres long and I have an inside sterring position as well as the helm outside at the stern.

[CaptNemoO2]

Why don't you just replace the servo with a shut off solenoid? When you want to kill the engine, you push a button to energize the solenoid until the engine stops. When there's no power, it returns back to the run position, so unless something goes really bad internally, you'll be able it to start to engine again. It's connected to the injector pump the same way with a cable.

[a64pilot]

I am very familiar with linear actuators, surprised you went that way as they are usually not inexpensive. Waterproof ones do exist, they are used on helicopter fuel controls and are used to adjust main rotor RPM, often called the beep switch by pilots, but they are most likely very expensive.
Linear actuators are excellent when you need fine control of positioning, you can’t get that with a solenoid they are all on or all off.
A solenoid with a spring however usually is relatively inexpensive they don’t need to be on all the time either, the spring holds the solenoid open so fuel will flow, a push button is used to close the solenoid, overriding spring and operating the lever that turns the fuel off, engine shuts down, you release the button that the fuel lever return to the open position via the spring. Very similar to a starter solenoid just way less powerful.
The failure mode is you can’t turn off the motor, a linear actuator fails usually in whatever position it was last in.

[a64pilot]

OH, either put a spring between the solenoid and the fuel shut off level or be sure it’s rigged so the solenoid hits it’s stop just a little before the lever, they are quite powerful and may could damage the lever or internals if the lever hits it stop before the solenoid does.
A spring would just stretch out if the lever hits it’s stop first

[FionaJC]

Originally Posted by CaptNemoO2

Why don't you just replace the servo with a shut off solenoid? Attachment 215261

This is the same as I have but its a sealed unit with a rod instead of a wire. The problem with a solenoid is that it doesnt have the torque to pull the lever on the injector pump and there is nowhere to fit it. Thats why I have mounted on a bulkhead behind the engine. I was just looking to see if a valve in the fuel ine would do the same job and Im coming to the conclusion it wont.

[a64pilot]

A solenoid has way more than enough torque, one engages your starter for instance and if you are old enough to have ever driven a car with a pedal on the floor to engage the starter, you know how much force that requires.
You can mount one anywhere you could mount a linear actuator and connect it the same way.

[FionaJC]

Originally Posted by a64pilot

..... if you are old enough to have ever driven a car with a pedal on the floor to engage the starter, you know how much force that requires.

No I haven't. The only button on the floor except the headlight dim switch was a starter button on a mini. Clutch, stop and go faster have been the norm. Ive only just got a car with two pedals last year instead of three.

[Bycrick]

I’d think that shutting off the fuel feed wouldn’t work. But I’ve only got one data point. My Yanmar 4JH2. Went out one afternoon. On returning, I pushed the STOP button on the panel. It kept running. Turned off the valves at the Racor filter. Kept running. Clamped the hose between the Racor and the motor. Kept running. Disconnected the hose from the valve. Kept running. I finally found something I could put over the air intake after removing the "filter" cover. It struggled for about 15 seconds and finally stopped. Total time measured in 10s of minutes.

I was later told that the secondary filter holds a fair amount of fuel and the engine doesn’t use much at idle.

[AKA-None]

A64 has the right idea as you want the failure mode to be in the way that makes sense. So do you want the failure to be run or stop? Personally I’d select run as I certainly wouldn’t want a failure to shut off the engine.

[a64pilot]

Solenoids can be very powerful. As a kid I built an auto shifter for drag racing motorcycles, the current state of the art back then was a Murdock air shifter but it needed compressed air and was only good for maybe one or two runs depending on the size of the air tank. I wanted something for street racing bikes. I used initially a starter solenoid, and promptly bent shift forks. I later used a washing machine solenoid meant for 120 VAC and ran it off of 12VDC and it worked fine, it was strong enough to shift but not so strong that it bent shift forks.
If any are curious I shorted the two coils together, this killed ignition and powered the solenoid, so a quick button push shifted gears and killed the engine for a fraction of a second for the shift to take place, the throttle stayed wide open.

But fist sized 12V solenoids can have bone breaking strength, much more so than a Linear actuator, issue is though that a solenoid is sudden and it’s travel isn’t adjustable, so you do have to check rigging before you push that button.

Back then we all removed the electric starters on the Kawasaki’s and I put my solenoid under the starter cover, so no one knew it was there, just thought I was a very fast shifter.

[Uncle G]

I've had a similar experience to the one Bycrick describes.

Turned the key to stop the engine, but it wouldn't stop (I later found out that the stop solenoid in the injection pump was sticking). I turned the fuel off at the tank. It didn't stop. I then tried putting my hand over the air intake. Didn't stop. I then discovered that there were small perforations in the nozzle leading to the air filter housing, so I hunted around for some sticky tape and covered all the holes. Then I put my palm over the end of the nozzle and the engine stopped dead. However, I then learned that I should have used something other than my palm - as it came up in a big red bruise from the suction.

Would it be hard to simply go to the engine and pull a knob/cable on or near the engine box to stop it?