Problem at injection pump?

[Ship's Cat 73]

Have a Volvo MD5A and there is no fuel getting from the pressure injection pump to the injector.
Fuel is present through the fine filter and to the injection pump -- fuel flows freely from the bleed screw at the filter and floods out of the 10mm nut at the pump but nothing gets to the injector, and I mean not as much as a single drip. (YES -- that screw and nut have been tightened when testing for fuel at the injector.)
I'm pretty much a "diesel virgin" but have to assume there is a problem at the pump???
Do these pumps fail, or have problems that I don't know about - - - and what can I be looking for?
. . . and finally, is it possible that some kind of blockage could cause this?
I did exactly as instructed in the online manual to test for air at the pressure pipe at the injector by slackening the large nut and turning the engine.

The nut is arrowed in the photo. (The 'white stuff' in the photo is just some kitchen roll placed there hoping to catch some diesel.)
.

 

[emmalina]

Lift pump ?

 

[penberth3]

Lift pump ?

Stop control in the "Run" position?

 

[snowbird30ds]

Stop control in the "Run" position?

More importantly is the lever on the pump in the run position, cables can fail.
Spin the engine over in neutral with the throttle full open and stop control in run position when checking with injector pipes cracked open.
I don't know the engine but assume the pump is gear driven with no failed drive cushions.

 

[Bilgediver]

Although it does not happen often and I have only experienced it once or twice in 30 years it is possible to get the fuel pump airlocked to the extent it can not purge the air out. If this happens then first prime till you are sure fuel is entering the injector pump. S.acken off the HP injector pipe at the fuel pump then also slacken the delivery valve housing. This is the item between the injector pump and HP fuel pump. Now turn the engine till fuel appears around of the threads at the base of the delivery valve housing. Tighten up the housing and turn the engine to ensure air free fuel appears from the injector pipe connection . Now tighten the injector pipe nut at the pump end and slacken thenut on the HP pipe to injector and again turn the engine till air free fuel appears. Tighten this nut and engine should start

 

[Ship's Cat 73]

Thanks to all for comments so far.

Was back on the boat today and first thing I did was slacken the 10mm nut at the pump (where the fuel is delivered from the fine filter).
No shortage of air-free fuel flooding out there.
Next, (after tightening that 10mm nut) was to slacken the slot-headed screw which appears tobe a bleed screw. Again, no shortage of air-free fuel flowing from there.
Tightened that screw then opened the 17mm retaining nut at the outflow from the pump and primed using the lift pump lever -- nothing. I then turned the engine with the starter for 20 - 30 seconds -- not a drop.
(Attached photo of pump -- an online drawing of the pump does not have the slot-headed screw that is present on ours.)
So I have to conclude that the problem definitely appears to lie in the pressure pump.
I've also included a scary looking exploded view of the pump - hope I don't have to try to dismantle THAT! (Drawing found on a Swedish site.)

 

[Bilgediver]

The bleed screw is in the inlet side of the pump.
See my preceding mail and slacken the top fitting where the yellow arrow points DO NOT REMOVE as may lose small items of delivery valve. When air free fuel appears retighten.

 

[penberth3]

The bleed screw is in the inlet side of the pump.
See my preceding mail and slacken the top fitting where the yellow arrow points DO NOT REMOVE as may lose small items of delivery valve. When air free fuel appears retighten.

Why are you suggesting that? If the injector pipe is disconnected it won't make any difference. and as you say there's the risk of disturbing the delivery valve.

 

[Bilgediver]

You have the delivery valve in that housing and it can stop the air which then just compresses in the pump. By slackening the valve body that air escapes up the threads followed by air free fuel.

This does work and as said before just slacken the valve housing as you may lose valve components if you try to remove the housing as this is not necessary..

 

[Ship's Cat 73]

Thanks for your further replies folks.
Just to be clear, can someone indicate on the attached exploded diagram which part should be slackened to allow the compressed air to escape.

The various components are all numbered in the diagram but the 'key' to these numbers is in Swedish . . . and I don't understand Swedlandish!
I'm guessing what I would need to slacken is item #3 (?)

 

[rogerthebodger]

MD5A - MD5B Volvo Penta Diesel won't go? Try this!

Have a look at the link above

 

[38mess]

I just did a job on my fuel injector pump.
You can slacken item 3 and even remove it quite easily. Just do it carefully because there is a spring and a small top hat type component that you might lose.

 

[Bilgediver]

Slacken

I just did a job on my fuel injector pump.
You can slacken item 3 and even remove it quite easily. Just do it carefully because there is a spring and a small top hat type component that you might lose.

Lose those wee pieces in the bilge and you may be stuck for ages hence the advice to just slacken as this reduces the force needed to allow the delivery valve to open. Maybe have to slacken a couple of turns.

 

[38mess]

Slacken
Lose those wee pieces in the bilge and you may be stuck for ages hence the advice to just slacken as this reduces the force needed to allow the delivery valve to open. Maybe have to slacken a couple of turns.

I agree. But hardly any force when I did mine. Item 3 is hollow and the spring and top hat item sits inside. Careful lifting of item 3 leaves the spring in place.

 

[Bilgediver]

I agree. But hardly any force when I did mine. Item 3 is hollow and the spring and top hat item sits inside. Careful lifting of item 3 leaves the spring in place.

A surprising number of people have lost bits in the bilge ven when being careful. Sometimes there is an access problem which exacerbates problems

 

[Refueler]

deleted ...

 

[emmalina]

If your spring #18 is broken it wont pump anything !

 

[penberth3]

Thanks for your further replies folks.
Just to be clear, can someone indicate on the attached exploded diagram which part should be slackened to allow the compressed air to escape.

The various components are all numbered in the diagram but the 'key' to these numbers is in Swedish . . . and I don't understand Swedlandish!
I'm guessing what I would need to slacken is item #3 (?)

View attachment 170787

No, if you've removed the injector pipe from the top of Part No 3 that will let air and/or fuel out. No need to disturb Part No 3.