BMC 1.5 Fuel Delivery System

[21FtFreedom]

Hi Folks.

First post in here. Actually first boat I've owned, and first engine I've attempted to fix. So appreciate all the help I can get.

I have 3 out of 4 working injectors. I also have fuel being delivered to all 4 fuel lines by the fuel pump. But for some reason, I have no fuel coming through the injectors.

I've put a video here to demonstrate: https://youtu.be/8Df_UCQf6T8

I can think of a few reasons why this might be, including no lack of pressure from the fuel pump. But before I go taking the fuel pump apart or replacing it, are there other reasons this might happen?

Many thanks in advance.

 

[spannerman]

Looking at your video it would point to the the fuel pump not building up enough pressure to lift the needle in the injector. Assuming of course the injectors are set to the correct opening pressure, if they worked before then the pump looks suspect.

 

[petem]

I have no idea but love your video!

 

[<152587>]

stop control not returned, worn injection pump, how long were you cranking, takes a while to displace the air in the injector pipes.

 

[21FtFreedom]

Thanks Spannerman.

Firstly, on the injector opening pressure:

One issue I have is that the injector pop tester I bought off ebay has a faulty pressure gauge (I sent it back). So I have no idea what pressure they are calibrated too. But....I figure it's unlikely that wrong opening pressure is the reason for all 3 not working?

On the pump:

I figure this could be the cause. But how can I tell? Is there a way to test the pressure the pump is creating? Like a hydraulic pressure gauge maybe?

How does the pump work? i.e. how does it create pressure in the first place?

Thanks again.

 

[21FtFreedom]

Looking at your video it would point to the the fuel pump not building up enough pressure to lift the needle in the injector. Assuming of course the injectors are set to the correct opening pressure, if they worked before then the pump looks suspect.

Thanks Spannerman.

Firstly, on the injector opening pressure:

One issue I have is that the injector pop tester I bought off ebay has a faulty pressure gauge (I sent it back). So I have no idea what pressure they are calibrated too. But....I figure it's unlikely that wrong opening pressure is the reason for all 3 not working?

On the pump:

I figure this could be the cause. But how can I tell? Is there a way to test the pressure the pump is creating? Like a hydraulic pressure gauge maybe?

How does the pump work? i.e. how does it create pressure in the first place?

Thanks again.

 

[kashurst]

Edit - not sure I have understood correctly do you have 3 working injectors or 4 working injectors? In you video you won't get any diesel out of your injectors until you have bleed the air out of the pipes.

The injectors you show in the video seem to be spraying beautifully. Once you have 4 working injectors then:
put all the injectors back in, reconnect all pipes and tighten up properly
(don't overtighten - you can always nip things up after if something is loose. You don't want to snap a bolt/strip a thread, hand tight plus 1/2 turn to start with - google how nuts and bolts work - lots of people don't understand properly)

Then slacken the fuel pipe nut on top of every injector half a turn. Now with an able assistant on the starter (or rig a switch on the starter motor solenoid), crank the engine till you get diesel coming out of the union/around the nut on top of all the fuel injectors where the pipe goes in. The engine might cough and splutter a bit but don't expect it to start.

Stop cranking, do the nuts up and now try and start it. Hopefully it will, but probably very rough. Then slacken each injector top nut in turn briefly, with the engine running, and see what effect it has on the engine and get any last bits of air out. Fingers crossed it will splutter into life then settle to a reasonable idle. Don't worry if it stalls a few times - just repeat.

A mechanical fuel injection pump is a fiendishly clever/complex thing and needs a lot of specialised kit to test, rebuild and calibrate. Might be worth phoning around for a local diesel fuel injection co - I am also guessing as its a BMC engine is more than a few years old so having the injection pump serviced/rebuilt/ or a recon and the injectors reset properly will be worth it in the long run.

If this is your first go at fixing an engine you are off to a great start, and the video is absolutely brilliant.
PS don't be tempted to just bend the fuel injection pipes - undo at both ends and take them off. (if you already have don't worry, just bend them back again carefully)

 

[21FtFreedom]

Edit - not sure I have understood correctly do you have 3 working injectors or 4 working injectors? In you video you won't get any diesel out of your injectors until you have bleed the air out of the pipes.

The injectors you show in the video seem to be spraying beautifully. Once you have 4 working injectors then:
put all the injectors back in, reconnect all pipes and tighten up properly
(don't overtighten - you can always nip things up after if something is loose. You don't want to snap a bolt/strip a thread, hand tight plus 1/2 turn to start with - google how nuts and bolts work - lots of people don't understand properly)

Then slacken the fuel pipe nut on top of every injector half a turn. Now with an able assistant on the starter (or rig a switch on the starter motor solenoid), crank the engine till you get diesel coming out of the union/around the nut on top of all the fuel injectors where the pipe goes in. The engine might cough and splutter a bit but don't expect it to start.

Stop cranking, do the nuts up and now try and start it. Hopefully it will, but probably very rough. Then slacken each injector top nut in turn briefly, with the engine running, and see what effect it has on the engine and get any last bits of air out. Fingers crossed it will splutter into life then settle to a reasonable idle. Don't worry if it stalls a few times - just repeat.

A mechanical fuel injection pump is a fiendishly clever/complex thing and needs a lot of specialised kit to test, rebuild and calibrate. Might be worth phoning around for a local diesel fuel injection co - I am also guessing as its a BMC engine is more than a few years old so having the injection pump serviced/rebuilt/ or a recon and the injectors reset properly will be worth it in the long run.

If this is your first go at fixing an engine you are off to a great start, and the video is absolutely brilliant.
PS don't be tempted to just bend the fuel injection pipes - undo at both ends and take them off. (if you already have don't worry, just bend them back again carefully)

@kashurst thanks for the vote of confidence! Needed that.

To clarify: I have 3 working injectors. The 4th injector had a damaged nozzle, which I haven't replaced yet.

Are you saying that I won't get any atomised spray from my injectors until I have all four attached??

In terms of bleeding the system, I followed the approach laid out by this video: https://www.youtube.com/watch?v=QXlXrnprFwU&t=33s

Important note: I'm also not getting any compression from the cylinders, which is a problem I'm trying to treat separately (and will start a separate thread to prevent muddy waters). Hence why I have the injectors sitting out of their seats; because I want to firmly establish that they are spraying.

@third engines mentions above that it takes a while to get all the air in the injector pipes. This video was probably taken on the 3rd or 4th crank. Should I keep going? I was doing 15 secs cranking, then leaving it for 2 mins, then 15secs again.

Thanks again.

 

[21FtFreedom]

stop control not returned, worn injection pump, how long were you cranking, takes a while to displace the air in the injector pipes.

Thanks @Third Engines. Appreciate your suggestions.

Stop control not returned? To what position? (excuse the rookie questions)

I was cranking on and off about 3 or 4 times. 15secs on, 2mins off, 15 on, etc. Should I keep going?

 

[kashurst]

The reason I suggested putting the injectors back in again is that getting the air out can be tricky and with the injectors all out as per video you may well end up needing 3 hands,as you need to be able to stop/start cranking and open loosen the pipe nut quickly on the fuel injectors that are hanging off the pipes. Also in that position as you re-tighten the injector pipe nut you may well be letting air back in, diesel out.

re cranking - yes will probably need to crank continuously UNTIL you see clear bubble free diesel coming out of the injector pipe nut. As you have taken them all to bits there will be quite a bit of air and it can be a bu@@er to shift sometimes. (30 seconds maybe more). I don't think leaving one injector off will make any difference, but I have never tried that.

Try the procedure I described.(if it makes any sense) crank continuously with the injector pipe nuts slightly loosened until you get clear diesel- then tighten them up. Then try cranking to get spray from the injectors. The engine in the video looks like new and is all ready to run, yours is definitely not and will probably need a bit more "encouragement".

EDIT sorry you stop control must be in the right position as you get bursts of diesel out of the open fuel injector pipes.
Stop control - if its in the "stop" position you wont get any fuel through. Find out where the stop slide/lever is on the fuel pump - should be a cable/wire connected to the fuel pump that goes to a pull-out knob with the engine controls at the helm. Make sure its working properly. i.e pull the knob out and look at the position on the slide/lever on the fuel pump, then push it all the way in and check position. Then undo cable at fuel pump and manually check how it moves or rotates - in and out/left to right. Once you are happy with how it works reconnect (maybe adjust too) the stop cable and check you get the same operation or movement.

However how bad is the compression problem?

poor compression could be:
cylinder head gasket- easy to change
damaged valves or valves gone rusty and not sealing - as per head gasket plus some new valves, maybe need to have valve seats re-cut, maybe damaged piston
worn out - re-bore, pistons, rings, bearings etc - big bill for parts and machining, look for a recon/ 2nd hand engine
melted piston - if you are lucky just a new piston and rings, if unlucky look for recon / 2nd hand engine.

 

[PCUK]

Have you bled the pump?

 

[<152587>]

Just noted that all injectors were not present and the leak offs were not connected. Some engines are particular to having a sealed system. Many engines will stop if the leak off is compromised.

 

[21FtFreedom]

The reason I suggested putting the injectors back in again is that getting the air out can be tricky and with the injectors all out as per video you may well end up needing 3 hands,as you need to be able to stop/start cranking and open loosen the pipe nut quickly on the fuel injectors that are hanging off the pipes. Also in that position as you re-tighten the injector pipe nut you may well be letting air back in, diesel out.

re cranking - yes will probably need to crank continuously UNTIL you see clear bubble free diesel coming out of the injector pipe nut. As you have taken them all to bits there will be quite a bit of air and it can be a bu@@er to shift sometimes. (30 seconds maybe more). I don't think leaving one injector off will make any difference, but I have never tried that.

Try the procedure I described.(if it makes any sense) crank continuously with the injector pipe nuts slightly loosened until you get clear diesel- then tighten them up. Then try cranking to get spray from the injectors. The engine in the video looks like new and is all ready to run, yours is definitely not and will probably need a bit more "encouragement".

EDIT sorry you stop control must be in the right position as you get bursts of diesel out of the open fuel injector pipes.
Stop control - if its in the "stop" position you wont get any fuel through. Find out where the stop slide/lever is on the fuel pump - should be a cable/wire connected to the fuel pump that goes to a pull-out knob with the engine controls at the helm. Make sure its working properly. i.e pull the knob out and look at the position on the slide/lever on the fuel pump, then push it all the way in and check position. Then undo cable at fuel pump and manually check how it moves or rotates - in and out/left to right. Once you are happy with how it works reconnect (maybe adjust too) the stop cable and check you get the same operation or movement.

However how bad is the compression problem?

poor compression could be:
cylinder head gasket- easy to change
damaged valves or valves gone rusty and not sealing - as per head gasket plus some new valves, maybe need to have valve seats re-cut, maybe damaged piston
worn out - re-bore, pistons, rings, bearings etc - big bill for parts and machining, look for a recon/ 2nd hand engine
melted piston - if you are lucky just a new piston and rings, if unlucky look for recon / 2nd hand engine.

Hi Kashurst

I meant to follow up on this much sooner, but I've been swamped with projects at work for past couple of months. Anyways, I've left the fuel pump and injectors for now to focus on the apparent lack of compression.

I tested the cylinders last week. My readings from right to left on the 4 cylinders was 75, 25, 50, and 150 PSI.

So, lack of pressure on all cylinders.

Firstly, I was doing my compression test through the glow plug holes, with the injectors screwed into place. One question I have - if anyone has an answer - is whether or not I need to have the atomising washer in place on the injector when I do this?

You'll see from pg48 of the manual (https://the-norfolk-broads.co.uk/downloads/bmc1500L-diesel-workshop-manual.pdf) that the injector has two sealing elements: the copper washer and the atomising washer. My atomising washers came out when I first removed the injectors, and I haven't replaced them yet. Will this affect my compression test, or should the copper washer above it be enough?

Secondly, how should I go about diagnosing where the pressure is being lost? You mentioned previously a few places where it might be leaking - pistons, rings, cylinder head gasket, etc. What's the best procedure for determining which of these it is? And is there something I can do initially that doesn't involve stripping it down? I've read a lot of forums that mention squirting oil into the cylinder to see if the pressure goes up, but is this the first step?

Many thanks.

 

[kashurst]

PM sent - solve your compression issues first
then check oil pressure - see pm
then if that all goes OK look at the fuel system.
then if it runs check cooling system

 

[PCUK]

Have dismantled the injectors as part of the service?