Bukh fuel injector pump - rack jamming

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stevd

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Good evening

Quick question as i am posting from my phone.

why is the rack on my bukh dv20 fuel injector pump / hp pump moving into the stop position on its own. its movivg forwards and then jamming as it seems its moving too far. how is this controlled. is it something to do with the idle position?

thanks
 
Hello again, now I am on my computer I will type out the problem a little clearer - I hope

I have a puzzling problem with my Bukh DV20 fuel injector pump. When I first install the pump with the rack set to the fully open position, it works perfectly for a few seconds. When the engine is running for some reason it closes off the fuel pump on the fuel pump rack completely. Even if the engine is started with with the throttle set to fully open on the morse controlls (which does move the throttle on the engine quadrant), this still happens.

Does anyone have any ideas why it would do this?

Has anyone got any experience with the govenor on these engines?

Many thanks

Steve
 
stevd said:
Hello again, now I am on my computer I will type out the problem a little clearer - I hope

I have a puzzling problem with my Bukh DV20 fuel injector pump. When I first install the pump with the rack set to the fully open position, it works perfectly for a few seconds. When the engine is running for some reason it closes off the fuel pump on the fuel pump rack completely. Even if the engine is started with with the throttle set to fully open on the morse controlls (which does move the throttle on the engine quadrant), this still happens.

Does anyone have any ideas why it would do this?

Has anyone got any experience with the govenor on these engines?

Many thanks

Steve
Click to expand...

Are you definitely engaging the pin on the governor rack in the fork on the governor mechanism.


After installing the fuel pump try moving the teleflex speed lever between stop and full speed with the engine NOT running. The fuel pump rack should follow your movements. If it does not then there is a fault in the governor, maybe a broken spring.


The setting of the armature on the stop solonoid is critical as this also does the job of maximum fuel control. If not set right then the engine might not run if too long or produce black smoke if too short.
 
The yolk which the fuel rack sits into doesn't move with the throttle control when the engine isnt running. I dont fully understand why, but this is normal. The throttle control preloads a spring and when the engine is running it then allows the yolk to move to control the fuel pump rack. It unfortunately doesnt move when the engine isnt running, which doesnt help with diagnosing.

There is no problem wth the open / max fuel position of the rack, its just the fuel shut off setting where the problem is.

I cant understand why the engine would go from fully open on the fuel to start the engine, which is normal, to completely shut. Is it because the engine needs to slow down after the engine is started and the govenor takes over and put the throttle / rack in to the required position?

Basically, is it normal for the fuel pump rack to go to the completely closed off position for a brief spell after the engine has started?
 
Just incase anyone else is having similar problems and reading this post in the future - it has been suggested by a diesel specialist to try adding some extra shimms. I cant see the logic as to why it would effect the rack but I will give it a try anyway. He seems to think he has seen something similar years ago due to there not being enough shimms. Its worth a try. Ill report back here if it works.
 
Make sure with the pump removed that the rack is moving as free as a bird from one stop to the other. Any binding or tightness, even very slightly, can stop the governor from moving the rack, or may cause stalling. The engine will start with the rack set at max fuel, once the engine starts the rack should pull back to whatever position you have the throttle set to. So if you have the throttle set at half setting for example, then start the engine, once the engine starts you then return the throttle to idle the rack will momentarily move to the no fuel position but once the engine revs drop it should then move forward to give fuel again.
 
'the rack will momentarily move to the no fuel position but once the engine revs drop it should then move forward to give fuel again' - thats exactly right. Unfortunately, when the rack moved to that position it was jamming, even though the rack moves freely when the pump is out of the engine. The pump rack will move over to the shut off position straight after startup no matter what the throttle position to slow the engine down, once that has happened it will then move the rack to the desired throttle setting.

After many hours of head scratching, bent over double and twisted at awkward angles in the bilges, I realised that when I was removing the pump the rack was returning to the open position. I then tried 'shimming' up the pump with papaer gaskets, and this worked in the sense that the pump rack was fuctioning as it should but of course the timing was out. I could start the engine but it was hard to do so. So it was obviously something to do with the govenor fork. I had thought about taking all the govenors off, manual and centrefugal (however that is spelt, I have no idea!) but decided I would sleep on it first. In a brainwave on my return I decided to take a persuader to the govenor fork, knowing that just the slightest movement would be enough to rectify it. And, it worked. the rack is now back in place and working correctly.

Just the slightest bit out was enough for the fork to jam the rack. Looking at the fork, you would not think that would happen. I figured this out after rebuilding the pump twice!!!! With a new rack, cogs, springs and piston/pumpy things!!!

Lesson to be learnt, if in doubt hit it with a hammer.
 
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