Diesel Engine cuts out

[Ross D]

I need some advice, our Volvo MD7A keeps cutting out when the throttle is put back to neutral. It is fine once the engine is warm but manoeurving in marinas etc when the engine has just been started is a pain.

The idle speed hasn't changed or been adjusted so I am reluctant to simply tweek up the idle so that it stops, because that won't cure the cause only mask the symptom.

My first thought was to strip and clean the injectors, I haven't serviced them since I bought the boat a few years ago so they are probably overdue for some maintenance. If this is the case can anyone suggest where I can get MD7A injector servicing kits or new injectors if it comes to that.

Many thanks

Ross

 

[mattlad]

Have you checked all the filters? Heater plugs? Fuel supply?

Does the fault still occur with an alternative fuel supply?

There is plenty to check before you start replacing injectors........

 

[Topcat47]

Richards brothers in Redruth will service your injectors and HP pump. I'd advise having both done together, then the injectors can be matched with the pump outputs. I've not used them, my local specialist is Panda in Fareham, but Richards do advertise the service. Servicing them is not usually difficult, but it ought to be done in a "clean room" and you probably won't have the necessary tools, I haven't had access to them since completing my apprenticeship and wouldn't consider doing it myself unless it was absolutely unavoidable.

The MD range have a cold start "button" usually at the back of the engine. This either advances the injector pump an iota or gives it a little extra fuel until warm up, I can't remember. From memory I think there's a bi-metallic strip that returns the settings to normal once the engine is up to running temperature. I never needed to use the button on mine during the summer, but it always helped at either end of the season.

I don't know how long you have owned the boat, but I did a top end overhaul on mine and lapping the valves, de-cokeing the head and wire brushing inside the exhaust ports and manifold made a worlds of difference.

One word of warning though, before you remove the head make sure the parts are available. not just Gaskets but valves, valve springs and manifolds. This is what killed my old MD. I needed a new manifold and water injection elbow which were unobtainable.

 

[pmagowan]

And check fuel lines. Almost all problems with diesel engins seems to be caused by fuel, in my experience. I had some pretty similar symptoms with mine caused by dirty fuel.

 

[Bilgediver]

.

The MD range have a cold start "button" usually at the back of the engine. This either advances the injector pump an iota or gives it a little extra fuel until warm up, I can't remember. From memory I think there's a bi-metallic strip that returns the settings to normal once the engine is up to running temperature. I never needed to use the button on mine during the summer, but it always helped at either end of the season.

I don't know how long you have owned the boat, but I did a top end overhaul on mine and lapping the valves, de-cokeing the head and wire brushing inside the exhaust ports and manifold made a worlds of difference.

The MD 7 has a rotary fuel pump on the side of the engine so no wee button on the back. However it does have a cold start
device on some fuel pumps depending which pump is fitted.


One pump has a wee lever under the cylindrical body of the pump and the other may have a lever adjacent to the speed
lever. Depends whether CAV or bosch.

The OP should check that the idle speed is definitely being set by the stop on the speed lever and not a position dictated by
the Teleflex!