Volvo ec27d Revs

[JerryRtilt]

A quick update on this annoying problem with the Volvo revs increasing as its turned off when auto idle is set, which i know could be simply resolved by me getting in the habit of moving the throttle lever to idle before turning the key, but I'm awkward and it stopped normally when it was new so i don't see why it shouldn't now
Anyway i thought i had cured it last weekend after Running a tank full of diesel with a additive in it on Saturday it was stopping normally, and i thought maybe the additive had cleaned something in the pump or elsewhere in the system.
Used it all week and its back to revving every time its stopped
Haven't really had time to f ck about with it during the week except for friday when i noticed it had some air in the filter bowl which i bleed out, didn't make any difference until the final time i stopped it before packing up for the week when it stopped without the revs increasing ?
It seems to get air in the system over a period of time and bleeding it out sometimes resolves the problem and sometimes not, Ive checked all hose connections and filter O rings etc and can't see anything wrong ?
Anyone have any ideas ? I can't see any non return valve that @Mick-the-fitter suggested could be in the leek off pipe, maybe fitting one would help ??

Thanks, Jerry.

 

[Mick-the-fitter]

Ok some other things to check! Does the fuel tank cap breath? Is the fuel supply pipe touching the bottom of the tank? When was the oil changed last?

 

[CPS]

OK I have a thought?
Does it only do it when auto idle is on?
If so I think what it is, is that the solenoid that actives the auto idle is shutting off as soon as the key is switched off.... meaning that for that few seconds it revs back to where the throttle is set?

 

[JerryRtilt]

Ok some other things to check! Does the fuel tank cap breath? Is the fuel supply pipe touching the bottom of the tank? When was the oil changed last?

I'd have to check if the cap breathes but I've never noticed a vacuum when opening it so i assume it does, the supply pipe definitely stays at the bottom of the tank as its a rigid pipe with a strainer that stays at the bottom, it may be coming up for a oil change, i do it as per the book at 250 hrs. what's your thinking re oil change ?

 

[Mick-the-fitter]

My thoughts were if the supply pipe is on the bottom of the tank so can’t get enough fuel, the engine oil idea in case the internal governor is getting stuck at its pivot! I have had to change a new one because it wouldn’t over ride throttle position ( Yanmar not Kubota)

 

[JerryRtilt]

OK I have a thought?
Does it only do it when auto idle is on?
If so I think what it is, is that the solenoid that actives the auto idle is shutting off as soon as the key is switched off.... meaning that for that few seconds it revs back to where the throttle is set?

Hi Aiden, yes only when auto idle on, i follow your thinking about the solenoid, it could be releasing the throttle cable fractionally before the engine stops turning , but why did it work fine when new, can't remember exactly when the problem started but my previous ecr25 did exactly the same ?

 

[JerryRtilt]

Hi Aiden, yes only when auto idle on, i follow your thinking about the solenoid, it could be releasing the throttle cable fractionally before the engine stops turning , but why did it work fine when new, can't remember exactly when the problem started but my previous ecr25 did exactly the same ?

Having thought about it a bit more i think i need to watch what happens at the pump while someone else turns the key of with auto idle on. ?

 

[V8Druid]

Hi Aiden, yes only when auto idle on, i follow your thinking about the solenoid, it could be releasing the throttle cable fractionally before the engine stops turning , but why did it work fine when new, can't remember exactly when the problem started but my previous ecr25 did exactly the same ?

if the solenoid is releasing the cable it should shut down surely ... cable usually pulls throttle open ... or does the auto idle operate a secondary linkage that pulls throttle position down from where ever it's set manually? .. then that would make sense ... however, as soon as the ignition is shut down, so too is the stop solenoid, presumably

 

[JerryRtilt]

if the solenoid is releasing the cable it should shut down surely ... cable usually pulls throttle open ... or does the auto idle operate a secondary linkage that pulls throttle position down from where ever it's set manually? .. then that would make sense ... however, as soon as the ignition is shut down, so too is the stop solenoid, presumably

I need to have a proper look at how the auto idle works, its buried behind the air filter, all i can see is the throttle cable and what looks like a pilot hyd. hose, i don't think it has a separate linkage. I agree about the stop solenoid, i would think that would override everything as it works directly on the pump ?

 

[jd6820]

OK I have a thought?
Does it only do it when auto idle is on?
If so I think what it is, is that the solenoid that actives the auto idle is shutting off as soon as the key is switched off.... meaning that for that few seconds it revs back to where the throttle is set?

I was thinking exactly the same thing. I'm betting it only happens with revs on maximum and auto idle set. I must admit I never shut down a machine even with auto idle on but ticking over without dropping the revs first. My bet is the residual magnetism in the solenoid coil is dropping off quicker as the solenoid is older hence why the machine didn't maybe have the fault from new but I suspect the machine is working correctly. The volvo's seem to have a manual throttle cable held in position by a solenoid to give you the revs/auto idle... (On the older Mini's I've worked on)

 

[JerryRtilt]

Had a quick look at the auto idle system today, its controlled by a small cylinder fed by what looks like a pilot hyd hose, that acts on the throttle cable outer, need to see exactly what its doing as someone else stops the machine, when the ignition is turned on there's a clunk which i think is the throttle being shut down to idle speed as it always starts at idle when auto idle is on regardless of where the manual throttle lever is set. If that makes any sense ?
also found a parts diagram.
This afternoon its started stopping (?) normally again without the revs increasing, the only thing that's changed is I've put another can of diesel in it with the additive that i used last time it was stopping normally, seems a strange coincidence ?

 

[V8Druid]

Had a quick look at the auto idle system today, its controlled by a small cylinder fed by what looks like a pilot hyd hose, that acts on the throttle cable outer, need to see exactly what its doing as someone else stops the machine, when the ignition is turned on there's a clunk which i think is the throttle being shut down to idle speed as it always starts at idle when auto idle is on regardless of where the manual throttle lever is set. If that makes any sense ?
also found a parts diagram.
This afternoon its started stopping (?) normally again without the revs increasing, the only thing that's changed is I've put another can of diesel in it with the additive that i used last time it was stopping normally, seems a strange coincidence ? View attachment 44108

sticking my neck out --- guessing that 2 in A is a prop., solenoid operated, valve, providing a limited amount of oil to the small cylinder 12 in B which is setting the throttle cable extension to the injector pump ... after given time the oil is released and the throttle closes to idle ... soon as a servo service is operated it bumps the throttle up by extending the small ram 12 in B .... et sec .... why it ups the revs when ignition is turned off is a bit of a mystery ATM ... will need to think about it more but it's obviously electrically related

 

[V8Druid]

how is your auto idle throttle setting set Jerry ... with a knob or manually by the throttle lever ?

 

[JerryRtilt]

sticking my neck out --- guessing that 2 in A is a prop., solenoid operated, valve, providing a limited amount of oil to the small cylinder 12 in B which is setting the throttle cable extension to the injector pump ... after given time the oil is released and the throttle closes to idle ... soon as a servo service is operated it bumps the throttle up by extending the small ram 12 in B .... et sec .... why it ups the revs when ignition is turned off is a bit of a mystery ATM ... will need to think about it more but it's obviously electrically related

That's exactly how i figured it, the throttle is also set to idle when you lift the left hand console/lever, which must be controlled electrically, but can't see that's relevant ?

 

[JerryRtilt]

how is your auto idle throttle setting set Jerry ... with a knob or manually by the throttle lever ?

Auto idle is switched on or off, throttle is a manual lever.

 

[V8Druid]

That's exactly how i figured it, the throttle is also set to idle when you lift the left hand console/lever, which must be controlled electrically, but can't see that's relevant ?

yeh agreed ... must dump the oil in 12 in B

Auto idle is switched on or off, throttle is a manual lever.

does auto idle automatically engage when you start the m/c and you have to turn it off if you don't wish to use it ? if that is the case then the valve 2 in A may just be a set volume of oil (not prop.) and that volume is dumped everytime it disengages ... the variation is purely mechanical on the initial throttle lever setting ... sticking my neck out further, if that is the case a spike from the alternator when the ign. sw. is turned off could result in 2 in A pressurising 12 in B ????? have seen some alternators have a capacitor fitted to 'dump' any run on spike to earth

 

[JerryRtilt]

Auto idle is switched on or off, throttle is a manual lever.

Quite a clever system, if not somewhat complicated. I'm still not convinced the revs increasing as its shut off is not fuel being drawn back from the leek off pipe as @Mick-the-fitter suggested earlier ? but i don't understand the workings of the pump and injectors well enough to figure out if that's possible ?

 

[V8Druid]

Quite a clever system, if not somewhat complicated. I'm still not convinced the revs increasing as its shut off is not fuel being drawn back from the leek off pipe as @Mick-the-fitter suggested earlier ? but i don't understand the workings of the pump and injectors well enough to figure out if that's possible ?

does auto idle automatically engage when you start the m/c and you have to turn it off if you don't wish to use it ? if that is the case then the valve 2 in A may just be a set volume of oil (not prop.) and that volume is dumped everytime it disengages ... the variation is purely mechanical on the initial throttle lever setting ... sticking my neck out further, if that is the case a spike from the alternator when the ign. sw. is turned off could result in 2 in A pressurising 12 in B ????? have seen some alternators have a capacitor fitted to 'dump' any run on spike to earth

 

[JerryRtilt]

yeh agreed ... must dump the oil in 12 in B

does auto idle automatically engage when you start the m/c and you have to turn it off if you don't wish to use it ?

No it operates whichever way the switch is set, it doesn't self cancel, i leave it on all the time and rarely change the throttle position as it starts at idle regardless of where the throttle lever is set. {I'm lazy}

 

[V8Druid]

No it operates whichever way the switch is set, it doesn't self cancel, i leave it on all the time and rarely change the throttle position as it starts at idle regardless of where the throttle lever is set. {I'm lazy}

Hmm ... it's getting an electrical surge/signal, when you turn it off, which bumps up the revs then, maybe, .... or.... it's sensing a servo pressure activation from somewhere ???

My Hydrema's system was something similar, but way more complex with 4 preset rev. setting selections .... had to bin it off and go to a manual throttle when it decided to give me grief