nickfabbri
Well-Known Member
Thank you that explains a great deal. In that case can someone please explain how the cold start works then? I assumed that it either worked like a choke in a petrol engine or it engaged some sort of glow plug
volvo md5 starting problems
- Thread starter nickfabbri
- Start date
Bilgediver
Well-Known Member
The cold start works by allowing the fuel pump to deliver an extra amount of fuel on startup. This is achieved by changing the length of the fuel pump operating lever during start up and once the engine fires rhe lever resets istself to the original length.
The change of length is achieved by the use of the controls as described by others....The same action occurs on may of the MD range though in some engines it is achived with a button,on some a cold start pull out knob and on others by pulling out the stop button and then returning it to the original position prior to starting.
The procedure basically is...
1. set speed lever to 1/2 speed engine out of gear.
2.Operate cold start device.
a.push button down till clicks
b.pull on cold start knob and replace knob full in.
c.pull on stop button and return to run position.
3.turn key to start engine.
If the engine fires but fails to start then the cold start will probably have tripped out and will have to be reset before trying to start again.
There was a pull knob mod for the original MD range which just operates a bellcrank fitted over the button by the fuel pump. Actuation is as 2a above.
John
The change of length is achieved by the use of the controls as described by others....The same action occurs on may of the MD range though in some engines it is achived with a button,on some a cold start pull out knob and on others by pulling out the stop button and then returning it to the original position prior to starting.
The procedure basically is...
1. set speed lever to 1/2 speed engine out of gear.
2.Operate cold start device.
a.push button down till clicks
b.pull on cold start knob and replace knob full in.
c.pull on stop button and return to run position.
3.turn key to start engine.
If the engine fires but fails to start then the cold start will probably have tripped out and will have to be reset before trying to start again.
There was a pull knob mod for the original MD range which just operates a bellcrank fitted over the button by the fuel pump. Actuation is as 2a above.
John
VicS
Well-Known Member
[ QUOTE ]
I assumed that it either worked like a choke in a petrol engine or it engaged some sort of glow plug
[/ QUOTE ] It will operate in the way that has already been suggested namely by allowing the injection pump to supply extra fuel. Have a look at the injection pump area and you should see what it is operating, it may be just a remote mechanism for drepessing a button as suggested. Predecessors of the md5 had a button that had to be pressed by crawling into the engine compartment, reaching down over the back of the engine and feeling for the button. A remote control was available at a price but was not fitted as standard. What does the operators manual say about operating it? The Workshop manual should show the mechanism.
Traditionally the choke on a petrol engine carburettor closed a flap valve in the air intake thereby causing a rich mixture (sometimes it is called a strangler) The choke on your outboard, or lawnmower almost certainly works like this, however many car carburettors had a mechanism that allowed extra petrol to pass without resticting the air flow. In some that was a multiported valve, in others it was a more progressive opening off a "valve" while in the older SU carbs that were used by many it lowered the jet assembly to enrich the mixture. The use of the word "choke" really ought to be restricted to the strangler type but in practice was used to describe them all. All that is obsolete of course now that cars have computer controlled fuel injection systems.
A glow plug is an electrical heater. It will be visible if fitted; it will located near the injector and will have a heavy cable connected to it as it will draw quite a large current. You might think it looked a bit like a spark plug. It would be controled either manually via a switch and relay or automatically via a relay/ timer that is actuated by the key swich in a similar way to the way it operates in a diesel car. (In those you switch on, wait until a dash board indicator light goes out and then start the engine in the normal way, some have an automatic fast idle system that works when cold others require a bit of throttle via the pedal. More modern systems are electronically controlled but i have yet to meet up with one of those)
However I am quite certain your engine does not have a glow plug so it will be a mechanical system, allowing extra fuel to be pumped to the injector, that is actuated by pulling the knob you described as "the choke" fully.
It is possible that the mechanism in the pump has become worn and that it is not engaging properly but until you follow the starting procedure given in the owners (operators) manual precisely we do not know that it is not starting as it should.
I assumed that it either worked like a choke in a petrol engine or it engaged some sort of glow plug
[/ QUOTE ] It will operate in the way that has already been suggested namely by allowing the injection pump to supply extra fuel. Have a look at the injection pump area and you should see what it is operating, it may be just a remote mechanism for drepessing a button as suggested. Predecessors of the md5 had a button that had to be pressed by crawling into the engine compartment, reaching down over the back of the engine and feeling for the button. A remote control was available at a price but was not fitted as standard. What does the operators manual say about operating it? The Workshop manual should show the mechanism.
Traditionally the choke on a petrol engine carburettor closed a flap valve in the air intake thereby causing a rich mixture (sometimes it is called a strangler) The choke on your outboard, or lawnmower almost certainly works like this, however many car carburettors had a mechanism that allowed extra petrol to pass without resticting the air flow. In some that was a multiported valve, in others it was a more progressive opening off a "valve" while in the older SU carbs that were used by many it lowered the jet assembly to enrich the mixture. The use of the word "choke" really ought to be restricted to the strangler type but in practice was used to describe them all. All that is obsolete of course now that cars have computer controlled fuel injection systems.
A glow plug is an electrical heater. It will be visible if fitted; it will located near the injector and will have a heavy cable connected to it as it will draw quite a large current. You might think it looked a bit like a spark plug. It would be controled either manually via a switch and relay or automatically via a relay/ timer that is actuated by the key swich in a similar way to the way it operates in a diesel car. (In those you switch on, wait until a dash board indicator light goes out and then start the engine in the normal way, some have an automatic fast idle system that works when cold others require a bit of throttle via the pedal. More modern systems are electronically controlled but i have yet to meet up with one of those)
However I am quite certain your engine does not have a glow plug so it will be a mechanical system, allowing extra fuel to be pumped to the injector, that is actuated by pulling the knob you described as "the choke" fully.
It is possible that the mechanism in the pump has become worn and that it is not engaging properly but until you follow the starting procedure given in the owners (operators) manual precisely we do not know that it is not starting as it should.
nickfabbri
Well-Known Member
Thank you all so much. will go try all of the above