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Old 10-26-2008, 08:25 PM   #1
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Fuel Shut-Off

Hey all you gear heads out there, a question. Will I cause myself trouble if I were to install a normally open solenoid valve in the low pressure fuel line on my engine. The engine is an old model Volvo 6 cyl. diesel that has a mechanical cable from the injector pump to the helm for shut off. It is not practical to extend this to the upper helm but I would really like to have a shut down control there as well. Thinking of installing a 1/2 inch solenoid valve at the input to the low pressure fuel pump that when energized would cut the fuel supply and stop the engine.
Anyone see a problem with this idea?
John Tones* MV Penta
Sidney, BC
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Old 10-26-2008, 09:24 PM   #2
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RE: Fuel Shut-Off

John -

I think that it will indeed shut down the engine, but it probably won't work the way that you want it to.

I'm assuming that you want a way to shut down quickly from the FB if something bad happens.* Perhaps you violated the depth-must-be-greater-than-draft law, perhaps you looked back and saw clouds of smoke... whatever.* So you'll pull the power back to idle, put it in neutral, and hit your kill button.

Unfortunately, your lift pump has a nice full stroke of fuel, and diesels are really miserly on fuel at idle.* So I could see it taking a minute or more for the shutdown to happen.

Take a look at my "stupid human tricks" post from a few months ago.* There, I had all 3 fuel tanks shut off.* I was able to start up, warm up, maneuver out of the marina, cruise out the channel to the marina, and get about a mile from the slip before the engines started to surge and cut out.* (Yes, it's very true that the fuel filters may have had some air bubbles in them that allowed significant fuel to be pulled from them as the lift pump pulled vacuum).*

In any case, I think that you could get down from the FB to the lower helm a lot more quickly than it would take to run down by cutting fuel to the lift pump.

If you could put the shutoff between the primary filter and the injection pump, you might be better off.* I don't know if the injection pumps have any sort of fuel reserviors in them to purge air - if they do, you still might have a wait.* Perhaps Rick will know.
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Old 10-27-2008, 06:24 AM   #3
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RE: Fuel Shut-Off

Penta,

this setup*should work just nicely. I have a "homemade" generator in my boat and have set it up the exact same way to stop the generator motor. The valve is placed after the lift pump just an inch from the injector pump. Like Chris says, this is not an instant kill switch. My generator will stop in*15 - 20 seconds after the solenoid valve is actuated.
At times I had problems killing the engine. It just kept on running after releasing the valve (I have set mine up to be NC / Normally Closed). I got a feeling that it was feeding off the return fuel somehow. After installing a solenoid valve on the return line, it stops as commanded every time.
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Roger Rossow
42' van Lent 1968
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Old 10-27-2008, 01:48 PM   #4
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RE: Fuel Shut-Off

I would not install a fuel valve, starving the pump of fuel might be a good emergency system but is not advisable as a normal shutdown method as it will cause cavitation as fuel pressure falls drastically.

There are many long stroke solenoids and linear actuators available that can be used to operate the existing shutoff lever.

You could even use a pneumatic cylinder to actuate the lever and drive the cylinder with air from your horn system if you have one installed. Your remote shutdowns would energize a three way air solenoid. Three way so that when not engergized, the cylinder is vented to atmosphere so that an air leak doesn't shut you down unexpectedly.
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Old 10-27-2008, 10:24 PM   #5
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RE: Fuel Shut-Off

Thanks for the input guys.
Rick - what I am looking for is an emergency way of shutting down not a remote, regularly used stop switch. We have had two occasions over the years when the ability to shut down NOW but remain at the upper helm has occurred. Both these were failures within the clutch controls and left me trying to stop the boat by steering, at a very slow speed mind you, into the dock. Had I been able to shut down the engine and eliminate the forward motion we could have just drifted until we were close enough to another boat to get a line secured or to get a long line to the dock with assistance. It is a real "pucker factor" when you cannot get the clutch to disengage and you are slowly powering down on moored vessels with no where to go.
I make it a habit to shut down the engine after letting it idle for some minutes and log the hours so that is always done at the lower helm where the mechanical stop control resides.
As I have discussed on this list before, my old Volvo / Bosh injector pump requires a "shut down lever" motion of about 3 inches so there are few options of solenoids to pull it or for that matter an air cylinder that would still mount in a position to function.
Bottom line, I am looking for a simple emergency shut down from the upper helm that is not going to harm the engine should I ever have to use the control.
Thanks again for all the info and suggestions and it looks like the fuel valve will meet my needs.
John
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Old 10-27-2008, 10:27 PM   #6
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RE: Fuel Shut-Off

Sorry guys - just re-read my original post and the plan is to install the shut down valve just before the injector pump, after the lift pump and secondary filters.
Again - the desire is for an emergency stop control not a routine use one.
John
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Old 10-28-2008, 08:10 AM   #7
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RE: Fuel Shut-Off

3" shutdown lever would be easily solved with a 3-1 bellcrank assymbly and a 1" throw solenoid. Or, since there is no law that the solenoid has to be attached to the end of the curent lever, an additional attachment point closer to the pivot would shorten the throw. Halfway back to the pivot makes it a 1.5" throw.

Having used both types of shutdowns, I'd lean towards the electric and the button for my upper helm. It's much simpler and one less break in the fuel line.

Just my thoughts, your's may vary,
Ken
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Old 10-29-2008, 08:57 PM   #8
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RE: Fuel Shut-Off

Hey guys,
A few days ago I posted a question about repairing the steps on my CHB under Taiwanese makes and hoped for some advice. Nothing yet..... Me thinks maybe no one has noticed it because of being posted there. If there is any help out there- please speak up!!
Steve

I tried to start a new post- couldn't. I can only post under a Quick Reply- what gives?
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