Engine seems to start but rolls to a stop

[JustinT]

I have heard fuel returning to the tank now, so, there is that.
Must do the gravity tank thing...

[GrowleyMonster]

Originally Posted by deblen

Sorry Growley. He had not tried gravity feed at this point.


My post should have read "If gravity feed doesn't cure the no start(and assuming gravity feed is supplying lots of fuel to inlet of inj. pump,and assuming inj pump is outputting HP fuel to INJ. nozzles and inj nozzles are spraying a proper pattern)


Then,I would check the injection timing mechanism for cleanliness & smooth operation. Then,I would go thru the inje. timing proceedure.


/ L

Ah my bad. I was reading and typing on my phone and I thought that was Justin saying he had tried gravity feed and it ran fine. Maybe I just had too many mojitos.

[Wotname]

Once again - back to basics!

The engine does fire and run for a short period - intermittently.

So from the videos and data to date, the engine is getting ample air.

That only leaves compression and fuel as the culprits.

Compression - very unlikely to be intermittent , especially when the valve cover has been removed. An intermittent compression problem could be caused by badly adjusted compression levers but removing the valve cover rules that aspect out.

Fuel - fuel problems are often intermittent so lets concentrate on the fuel side things.

Q1. Has the high pressure injection pump ever been removed and refitted in recent times? If NO, then we can likely rule out any timing issues and besides, timing is unlikely to be intermittent.

If timing issues are ruled out issue, then lack of fuel to the cylinders is the only thing left.


Possible fault areas:
A. Injectors - have been serviced so rule them out.
B. Injector pump - possibly intermittent but not common.
C. Governor (centrifugal and manual) - possibly intermittent but agin not common
D. Stop button (or solenoid) - possibly intermittent
E. Lift pump - possibly intermittent but normally is go / no go rather than intermittent.
F. Fuel filter - sometimes intermittent
G. Air in fuel system - often intermittent
H. No fuel - rarely intermittent

As other's have said, rule out as many variables as possible. Rig up a temporary supply of gravity fed CLEAN fuel directly to the injector pump. It doesn't have to be much, a cupful is ample for testing. This will eliminate E, F, G and H from the suspects. I would use a clear tube with a funnel at one end and the other end connected to the injector pump.

Report back!

If it still won't run, then we will need to look D & C (in that order) but let's wait until E to H has been tested and ruled out by the gravity feed supply.

[skipperpete]

I’m thinking that now is a good time to pay less attention to starting the little Bukh and more to stopping it in anticipation of it taking off into high rpm as in the previous episode. There are a number of possible causes for an overspeed and the easiest way to stop er is to block the air intake (assuming the intake manifold doesn’t have a hole in it for the crankcase breather) or undo the high pressure fuel connections. The most obvious first step though would be to test the stop control with the injector pipes loose. Start cranking and watch the fuel come out of the HP unions then pull the stop (still cranking) and hopefully observe zero fuel at the unions. Its actually fairly difficult to get a 2 cylinder engine to overspeed, the process usually involves a plunger to jam in the injector pump and lock the rotation ability of the rack so its down to a one cylinder runaway and consequently easier to arrest. Avoid the temptation to use the decompressors unless its a dire emergency and you’re ok with doing the bent pushrod and valve job again.

[skipperpete]

I’m hooked on the Bukh workshop manual, what a great little engine, a big thanks to the guys who posted the link. I had previously worked on the saildrive and done a few small jobs on these engines but was never a big fan other than for the saildrive, that thing is a work of art. Not one, but TWO diaphragms, ZF clutch mechanism, not unlike the SD60 , a real winner.
The injection timing method is archaic but if you hack away the excess detail its just the same as for any spill timed cassette injector pump, most of the convoluted instructions refer to finding TDC and injection point when they could have quite easily put timing marks on the flywheel instead of training the hapless owner how to do exactly that….. its not like a factory installed timing mark on a flywheel might need to be checked for movement. Which diesel mechanic owns a “ Sphygmomanometer”???, most of us use a capillary swan neck or even more commonly, a little flashlight beam on the delivery valve meniscus. Same gig with the shims…. Too many shims under the pump is late timing, too few shims is advanced (as well as the risk of destructive collision with the plunger head clearance). This engine also has an auto advance mechanism that operates at higher rpm. I very much doubt that the timing is off but if I was there, I would probably check it….. which means going through the ordeal of creating the timing marks…. Ugh.

[JustinT]

Thanks so much chaps. Much to work on there.
I'm still not convinced I have the rockers gapped correctly.

[Wotname]

Originally Posted by JustinT

Thanks so much chaps. Much to work on there.
I'm still not convinced I have the rockers gapped correctly.

Providing there is some gap, it won't stop the engine from running (at no load) unless the gap was so big that the valve didn't move.

[JustinT]

Originally Posted by Wotname

Providing there is some gap, it won't stop the engine from running (at no load) unless the gap was so big that the valve didn't move.

Thank you

[JustinT]

Well, I'm struggling to work out how to do the gravity tank. My pipes are mostly metal with banjo fittings at the end.
Then I keep looking at the fuel coming out the check valve on the fuel filter and the pulsing fuel from the injector pipes.
On trying the engine it is so running until I let go of the key/cranking.

I have loosened the cylinder cover to rule out the compression holding the rockers.
I have wound out the solenoid so it's in no way stopping the running.

[deblen]

https://youtube.com/shorts/6lqyWVqTJ...vIhPQqf5JAR7hi


Guys. Do you think there is enough valve clearance?
Are the valves seating?
Is there compression enough?

[Wotname]

Originally Posted by JustinT

.......
On trying the engine it is so running until I let go of the key/cranking.

.........

OK, a couple of days back, the engine appeared to run OK for a some seconds after the key was turned off. Or have I missed something in this video?

Originally Posted by JustinT

Today's frustration
https://youtube.com/shorts/dqHdS883e...dK7VShy5Ma7ej7
Regulator rolled back, solenoid loosened off

[Wotname]

Originally Posted by JustinT

Well, I'm struggling to work out how to do the gravity tank. My pipes are mostly metal with banjo fittings at the end.
........

Yes, that does make it a little more difficult. What sort of fitting is used at the inlet side of the lift pump (see attachment)? The manual I have suggests it is a banjo fitting with a hose nipple. If it is, can you remove it and fit it onto the inlet of the injection pump. That would allow you to use a flexible hose (preferably clear) from the hose nipple to a small funnel.

[JustinT]

Originally Posted by Wotname

OK, a couple of days back, the engine appeared to run OK for a some seconds after the key was turned off. Or have I missed something in this video?

It did indeed appear to be running that near first time when it was running fast, however, I still feel that once I let go of the cranking/key it begins to stop. Possibly that running fast time it just lasted longer because it was running so fast/crazy.

If it was a petrol I'd say it was electrical, but being a diesel....

There is no real time for for a very long time I have thought "oh that is so running now" now it is "that really sounds like it's going now, I'll stop cranking" only to have the same thing happen

[JustinT]

Originally Posted by Wotname

Yes, that does make it a little more difficult. What sort of fitting is used at the inlet side of the lift pump (see attachment)? The manual I have suggests it is a banjo fitting with a hose nipple. If it is, can you remove it and fit it onto the inlet of the injection pump. That would allow you to use a flexible hose (preferably clear) from the hose nipple to a small funnel.

I think the inlet side of the lift pump is a rubber hose with a jubilee clip... I'll go back shortly and check.

[Wotname]

Well you are on the spot and are in the best place to know how it sounds. My previous analysis has been based on what I understood the engine has operated a few times for some seconds after the key is switched OFF. This lead me to think it is an intermittent fuel issue however if it has always 'rolled to a stop' then the fault is not intermittent.

If not intermittent , then it maybe a compression problem - as Deblen mentioned just earlier.

We need to isolate it one way or the other.

Thinking...