Maybe a silly Q but - how does one stop a Diesel Engine running ?

C

Capt Popeye

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Yep certainly silly question one might think; yea turn the Key Off, but Diesels do not have ignition do they ?

Are they starved of Fuel to the injectors or something like that ?

Are there various different ways to stop a Diesel running ?

I used to use the Decompressor to get the (my) engine turning over then drop the Decompressor and low behold she fired up (mostly ?) but I did not stop her running using the decompressor; so guess I just starved the Injectors from fuel ?

I have asked friends who are real Motor Buffs and they just stated, turn the KEY to off - yea so what does that actually do ? dunno is the answer, but it works !

So please even if its a bit light hearted, anyone know ?

Thanks CP
 
Capt Popeye said:
Yep certainly silly question one might think; yea turn the Key Off, but Diesels do not have ignition do they ?

Are they starved of Fuel to the injectors or something like that ?

Are there various different ways to stop a Diesel running ?

I used to use the Decompressor to get the (my) engine turning over then drop the Decompressor and low behold she fired up (mostly ?) but I did not stop her running using the decompressor; so guess I just starved the Injectors from fuel ?

I have asked friends who are real Motor Buffs and they just stated, turn the KEY to off - yea so what does that actually do ? dunno is the answer, but it works !

So please even if its a bit light hearted, anyone know ?

Thanks CP
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In an emergency a CO2 extinguisher discharged into in the air filter.
The non emergency answer depends on the engine. Mechanical diesels won’t stop if you remove power so turning the key off won’t work.
 
Capt Popeye said:
Hi thank you; to fuel isolate is the Fuel Pump isolated so that the Diesel is not being pumped to the Injectors ? or is the Diesel fuel returned through the return fuel pipes ? so not reaching the Injectors under pressure ?
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Pump-Out said:
Some decompress. Some fuel isolate. Some do both.
Click to expand...

Not enough information to know. In a common rail Diesel the injectors stop injecting but there is still high pressure fuel reaching them. In an old fashioned diesel there is usually some sort of fuel shut off in the pump which stops the fuel getting to the injectors. Often an electrically operated solenoid that pulls a lever that you can also operate by hand.
 
The injector pump contains the "fuel rack" which adjusts how much fuel is delivered - more to go faster, less to go slower (it's controlled by the governor, not the throttle cable directly). Normally the slow end-stop is idle speed; pulling the stop lever moves the end-stop so that it delivers even less fuel than idle, not enough to keep the engine running, and it stops. Some engines use a bowden cable to move the lever, some a solenoid controlled by the key or a stop button, but the effect is the same.

(If your engine has decompressors, it's not the sort of modern electronically-controlled engine that Elessar mentioned.)

Pete
 
I don't know about modern diesels, but in old basic ones the fuel rack determines the amount of fuel being Injected, giving full revs at one extreme, and stop at the other. In extremis a diesel can also be stopped by preventing air getting in to it.
 
Well it's not a stupid question because I've just realised I've no idea what the little electric switch on mine actually does ;-) thanks.

(or we're both shtoopid)
 
Not a silly question at all Popeye. I know from first hand experience how embarrassing it is when you cannot stop your engine. A couple of years ago, prior to the first outing of the year I fired up my Yanmar to check all was well. Battery fine, started immediately. Ran it for 15 minutes to warm everything , then went to the cockpit and pressed the red KILL button as usual. No change, ending running smoothly as ever. Assuming the contacts in the red button were corroded I shorted out the two wires to the button; no change. Slightly worried, I rummaged down below and turned the fuel supply lever to OFF; still no change. Dragged out the Yanmar manual, expecting to find some lever down by the injectors that would cut the fuel; pathetic manual with diagrams drawn by a spastic, no mention of a KILL lever. Went on YouTube for help. Read and half understood that the fuel supply lever was probably thwarted by the return fuel system. One suggestion was to cut the air supply instead, so I found a suitable size wooden plug and rammed it up the air filter intake; engine half throttled, but manfully refused to die completely. Removed the bung. By now it was Saturday evening, no engineers within call out range, so we sat down to supper with the engine burbling away happily. Fuel tank was full, so at least no danger of clogging the injectors with whatever gunk lies at the bottom of the tank. Went around all the other boats in the marina to see if anyone had any new ideas. Lots of helpful (!) comments. Went to bed. About tennish next morning (Sunday) a very nice pal turned up with his Sunday lunch guest, who he said was an engineer on a cruise liner. This poor fellow was all in his posh weekend clothes, but he stripped off and set to to examine the engine. Of course he quickly identified that we have a fuel cut off operated by a solenoid (not marked in the Yanmar manual....) but that my solenoid was well and truly rusted solid. To his enormous credit, he set too with a spanner or two, working over the top of a very warm engine, and managed to cut off the fuel supply. My hero!!
When the Yanmar engineer arrived to replace the solenoid, we took great care to identify exactly how to get a long rod in behind the solenoid to operate the little lever that does indeed cut off the fuel to the injectors. End of a very bad start to the holiday.
 
From what little info you have given it’s probably a stop solenoid that is activated by the key. It will be activated to most likely release fuel pressure preventing fuel from going through the injectors.
 
Diesel engine requires air and diesel to run and plus lubricant and cooling to keep it running
starving it will eventually stop it but under certain circumstances it will run on its own oil so only certain way is to eliminate air supply
Either a flap or perhaps an airtight bag for definite stop
 
scottie said:
Diesel engine requires air and diesel to run and plus lubricant and cooling to keep it running
starving it will eventually stop it but under certain circumstances it will run on its own oil so only certain way is to eliminate air supply
Either a flap or perhaps an airtight bag for definite stop
Click to expand...
really bad advice except on tiny engines
 
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