Diesel engine problem

[pappaecho]

Started the engine at the entrance of Pompey harbour, and it started fine, but ran slower and slower and gave out near Hardway, so sailed onto the club pontoon. Checked that there was no problem with prop, no rope or bags round it.
Checked the flow of diesel from the primary filter, which was fine.
Started the engine which ran at maximum revs for 4 minutes ( with throttle set at minimum). The solenoid stop would not work, and in the end I had to pinch the rubber tube on the inlet to the injector pump to stop the engine. Checked the solenoid stop valve and it clearly clicks meaning it is working. Also checked the manual emergency stop which again would not stop the engine.
Anybody got any clues as to what is going on. Engine is Beta 35 which thus far has been good as gold.

 

[boatmike]

That's an unusual one but could possibly be a broken regulator piston return spring in the fuel pump or grit behind the piston jamming it . One way or onother it is a good bet that it is fuel pump related so the best thing to do is remove the fuel pump completely and get it tested by a specialist. There are several local to Portsmouth. I have used Panda Fuel Injection in Fareham 01329 220551 before and they did a good job.

 

[richardabeattie]

Can't answer the question but surely the quickest and safest way to stop a runaway diesel is not to reach into it for a fuel line but to block the air intake with something other than your hand - a plastic plate from the galley?

 

[Guest]

If the engine runs without throttle control and cannot be stopped by normal stop button - it's possibly diesel has got into sump with lub-oil ... then engine basically runs on the sump oil passing the piston rings.
I was told that only way to find out is to drain the sump and check the oil that comes out to see if its mixed with diesel ... but maybe a mechanic can elaborate better than I ..

I was really afraid that was the problem with my engine recently ... but I was lucky that stop button did stop engine as normal ... only trouble I had was engine would rev to max even with lever at minimum.
I've changed the injection pump and all seems fine now ... old one is in service having diagnostics to find out why ... we believe its the governor has broken internals ...

I hope for you that it is pump problem ..... and not more serious as in running of the sump.

 

[gandy]

If running on sump oil, interrupting the fuel flow wouldn't have stopped it.

 

[richardabeattie]

Yes - that's why I suggested shutting off the air!

 

[pandos]

We used to have similar problems with a dumper, Often had driver going around in circles. It was something to do with the anti stall/ govenor. as opposed to the pump.

 

[boatmike]

I have heard this story of diesel in the sump oil before. It is one of those perannial stories that everyone comes up with but no one ever seems to be able to substantiate. In many years dealing with diesel problems I have never seen it and would like someone to tell me a) how the fuel gets into the sump in sufficient quantities to cause the problem in the first place, and b) how it gets up to the combustion chamber in sufficient quantities to support combustion.
I am convinced that the majority of problems of this nature are caused primarily by dirty fuel. A diesel fuel pump is a fairly delicate precision device that should be protected by filters that are regularly cleaned. Often on boats the use is intermittent allowing gum and lacquer to form when the engine is idle and filters are not cleaned until fuel blockage takes place. It only takes one tiny piece of grit to jam a control piston. I would bet a pound to a pinch of poo that this guys problem is similar to yours and that if he fits a service exchange fuel pump the problem will go away.

 

[jleaworthy]

The operation of the governor depends upon no air being in the fuel. It sounds strange but a small amount of air in the governor can cause the engine speed to rise sometimes by quite a lot. I think you could well have an air leak on the suction side of the lift pump.

 

[pappaecho]

Thanks for the input. The engine has done 35 hours from new, as it was changed in march. Beta think it is an injector pump problem, and if the pump had jammed then the stop buttom would not have worked. Must remember that the air cut off method is a lot quicker than the fuel cut off method!

 

[RivalRedwing]

Installed in March therefore a warranty issue (presumably?) please, in due course, give us an overview of the speed and quality of Beta's response

 

[pappaecho]

Raised problem at 9 am today. Engineer will visit the boat tomorrow at 4 pm to do an assessment. Response therefore must be classifed as very good

 

[Heckler]

nigel, nah nah nah, detroit deisel two strokes do things like this, but burn oil from knackered supercharger oil seals, your way off the mark on this one!
pound to a pinch of [--word removed--] its a pump prob.
Stu

 

[uforea]

There are a couple of ways that Diesel can get into the sump which thins the oil and increases the quanity which then produces more vapour which in turn is then fed into the inlet manifold via the breather tube and so the engine takes off and can only be stopped by stalling it (in a car or lorry) but as this cannot be done in a boat so the engine would eventually destroy itself but not before everything downwind disappears in a cloud of thick black smoke. Diesel gets into the sump via the leaking diaphram of a mechanical lift pump on the side of the engine or through the front seal of the injection pump itself. Trying to restrict the airflow will not work as the engine will then just pull more air/vapour from the breather tube, in any case the amount of air that a runaway diesel draws in would probably pull a plate ,your arm and most of your upper body in as well. The only way to stop an engine in these circumstances is to get the breather off and away from the inlet manifold. As to the original post I would be very surprised if the injection pump was faulty being so new and would look more closely at the solenoid or possibly an air leak as a better bet.

Ted.

 

[Guest]

[ QUOTE ]
If running on sump oil, interrupting the fuel flow wouldn't have stopped it.

[/ QUOTE ]

I did note that - but was puzzled that the stop button didn't ...

 

[Guest]

I was only passing on what was considered as problem on mine as well recently ... mine turned out stuffed guv'nor ...

Anyway - he's got ginger beer looking now under warranty.

 

[Heckler]

now now niggely, dont get sniffy on me!! stop button is part of the pump usually, it pushes the rack past the fuelling point to no fuel, if the governor/pump bits are shagged the stop mechanism wont push the rack to the no fuel position, easy peasy once youve opened one up. by the way that is the way most pumps work before some smart arse comes in about some strange engine!!
open an old detroit diesel or a cummins up and see the push rod operated injectors etc and get your head around them, then think detroit diesel is a 2 stroke, with transfer ports halfway up the cylinder, then think cant get enough compression with only half the cylinder available to let it compress so you put a supercharger on to boost the cylinder pressures, then you put a turbo charger on as well to give it some more oomph, then get worn oil seals in the supercharger and then it will run away on its engine oil as fuel, and then you see a mechanical flap in the intake to stop it if it does!! then if you are in the oil field you can also stop the engine if it runs away from stray gas entering the inlet. shall i go on??
Stu

 

[Bilgediver]

This IS a problem and if you look at the Volvo or Bukh engines you will see they have the fuel pump mounted inside the crankcase with just the tops of the pumps visible on a top surface. All fuel pumps have leakage past the plungers, they would ssieze if there wasn t however when the pumps get old and worn this leakage becomes excessive and guess where the leaked fuel goes????????

This is one reason for the high frequency of oil changes as there is always fuel dilution taking place and yes in a worn engine it is possible for the engine to run on uncontrolled using the oil getting past the rings as fuel and the only way to stop it is to block the airflow.

Mind you if this happenes you could say you need new fuel pump parts and at least new rings.. /forums/images/graemlins/laugh.gif /forums/images/graemlins/laugh.gif /forums/images/graemlins/laugh.gif

On all the MD engines it is not unusual for the engines to appear as if there is zero oil consumption however what is actually happeneing is that oil which is burnt off is being replaced by fuel leakage.

 

[boatmike]

As I served my apprenticeship with CAV over 40 years ago I claim to know a bit about fuel pumps. As I said in my post I bet a £ to a pinch of poo that you find a jammed piston or broken spring in the fuel pump.
To all those who say this is due to fuel somehow getting in the sump I say simply that I have never seen an instance of this causing your sort of problem on a little marine diesel. I have however seen, stripped down, and rebuilt very many fuel pumps on the same sort of engine usually due to dirty fuel. While fuel in the sump may be theoretically possible it's therefore at best a very rare occurrence in an engine like this in the quantities required to support continuous running and would not explain all of your symptoms especially slowing down on its own and not responding to throttle. I would also say to the red herring merchants that this is a small very simple four stroke marine diesel, not a 2 stroke with fuel bypass chambers and does not have a turbocharger or supercharger. Also the symptoms you describe, first slowing, then speeding up, and not responding to solenoid cut off, are stereotypical of a fuel pump problem. When you eventually get it fixed (under warranty I hope) please let us know. Anyone who wants to take a side bet I am up for it!
As an additional point, new engine or not, when you get a new fuel pump on please check the fuel in your tank, fit new filter elements, and flush out your fuel lines before knackering that one too!

 

[steve28]

I had this problem on my 2gm20 when i filled up with falmouth harbour masters fuel, it seemed that the barge had next to no fuel and lots off water. the effect was identical to what is being described.
I only fill up there now when i know the tanks are reasonably full.