Why my MD7A is doing this?

[Metacentre]

Hello everyone!

Here is the video;

Looking for all kind of suggestions except throw this old engine away as i love my old friend and so far he was so reliable

When i start the engine it runs like a normal (idle) then rpm increasing and normal up and normal, then it goes up and at certain point engine stops. If you watch the video you see it starts at idle and goes up. Always similar pattern.

What i did so far;

New water separator with pre-fuel filter installed (as my old lift pump was so dirty)
New lifting pump installed.
Did bleed the system but i have never seen an air bubble free fuel lines on this engine so i assume little bit air running through is ok or i should look for air leakage?

Also if there is air in the system engine should loose power right not increase the rpm?

Today i started to think that maybe injectors are not working well and spraying too much fuel and after certain point it is too much fuel and engine stops.

I have bosh injection pump installed, i am not sure if it has problem (hopefully not).

Thanks!

 

[Johnb]

I am an electrical and controls engineer, so I vote for the governor. Go looking for something sticking, springs loose or broken, weights come loose etc. that could account for all the erratic speed symptoms.

 

[Alan Gomes]

Did bleed the system but i have never seen an air bubble free fuel lines on this engine so i assume little bit air running through is ok or i should look for air leakage?

You should have no air in the fuel line--not even a little. Even a small air leak will cause problems.

Don't mess with the governor. While they can fail it is much less likely, and you have already indicated something is clearly wrong with your fuel system.

 

[jssailem]

I can only speak from my experience with my Perkins 4107. When I had fuel starvation issues (clogged fuel filter)the diesel engine would run up RPM. Die back then run up and stop. If I caught the run up early (at the first sign), I could stop the engine. Turn off the fuel flow. Change the filter, fill the new filter and bowl, then start the engine with out bleeding the lines.

Yours appeared to react the same way. I would look at the fuel lines. Perhaps there has been some contamination. Start with the fuel tank uptake. Is there a screen in the tank? If so remove the screen. They can collect crud when fuel is being sucked, then drop the crud when the engine quits, only to suck up crud again.

Look as all bends and connections for fuel goo. It is a thick gelatin mass of diesel resins that can clog fittings and hoses. The hoses are not very large ID so even a little contamination can reduce your fuel volume. Be sure you primary and secondary fuel filters are clean. Check the fuel line connections for fresh o rings either rubber or copper. No leaks of fuel or air. Finally check your atomizers to be sure they are clean and applying the proper amount of fuel.

Good luck.

 

[Whatfiero1]

Start basic check fuel tank vent by open fill cap, then make sure pickup tube not clogged blow air backwards to tank to clear it if air leek usually before the high pressure pump 3rd thing would be to change all banjo washers u didn't change with pump replacement

 

[Ralph Johnstone]

When working on your engine, start with the simplest (and cheapest) items first. The governor would be amongst the last things you check.

 

[SycloneDriver]

In the video, did the engine die or did you pull the fuel stop?

 

[Tally Ho]

Are you saying you were not increasing the throttle...it just revs up by itself?

it sounded like there was some strange knocking noise as the engine RPMs went up.

greg

 

[SEMPERAVANTI41]

I would attach a temporary fuel supply directly to the injection pump, with a fresh fuel supply. If the engine then runs correctly, the problem is in the fuel system. If the engine does not run correctly, the problem is in the engine.

 

[Metacentre]

Hello Everyone!

It is fixed thanks to you all and my md7a is the happiest now!
It was the clogged tank sucking line! :s
I made a plan based on these comments and went on board today. As Whatfiero1 said, went inside the small hatch on the port side and took the suction line out from the tank.
As soon as I took it off, black jelly dirt came out then I took my hand pump and connected and started to suck a a lot.
It is like a ketchup first small peaces then more and boom big dirt came out. Then clean fuel started to come.
I connected everything, did bleed the system and now working better than ever.

And as Ralph Johnstone said, again and again always start with the simplest and cheapest one

Thanks again!

 

[jssailem]

I would look at the fuel lines. Perhaps there has been some contamination. Start with the fuel tank uptake. Is there a screen in the tank? If so remove the screen. They can collect crud when fuel is being sucked, then drop the crud when the engine quits, only to suck up crud again.

Sounds Like I may have nailed it... @Metacentre Do we get a prize... A pair of those little wooden shoes or something?

If I had wooden shoes I could practice putting my finger in the hole in the dam and and saving the town.

Happy you found the solution and that it was the simplest is a real bonus.

 

[Alan Gomes]

Hello Everyone!

It is fixed thanks to you all and my md7a is the happiest now!
It was the clogged tank sucking line! :s
I made a plan based on these comments and went on board today. As Whatfiero1 said, went inside the small hatch on the port side and took the suction line out from the tank.
As soon as I took it off, black jelly dirt came out then I took my hand pump and connected and started to suck a a lot.
It is like a ketchup first small peaces then more and boom big dirt came out. Then clean fuel started to come.
I connected everything, did bleed the system and now working better than ever.

And as Ralph Johnstone said, again and again always start with the simplest and cheapest one

Thanks again!

Congrats on finding the problem. If the pickup tube that goes into your tank has a screen on the bottom of it, you should definitely remove it. Those are nothing but trouble.

 

[SEMPERAVANTI41]

When I installed a generator in my 41DS, I installed a valve that allows fuel feed to the engine from either the engine pick up & engine filter or the generator pick up & generator filter from the common diesel tank. If my engine filter gets clogged, turning a valve feeds from the generator filter. Installed about 7 years ago, glad has not need to be used!

 

[Metacentre]

Sounds Like I may have nailed it... @Metacentre Do we get a prize... A pair of those little wooden shoes or something?

If I had wooden shoes I could practice putting my finger in the hole in the dam and and saving the town.

Happy you found the solution and that it was the simplest is a real bonus.

Haha Sure thing! Let me know when you are around Amsterdam ill buy everyone a one new pear of wooden shoes (Klomp)

 

[Metacentre]

Congrats on finding the problem. If the pickup tube that goes into your tank has a screen on the bottom of it, you should definitely remove it. Those are nothing but trouble.

Yes already on my to do list, i will clean the tank and remove if there is any screen, good point!

 

[jssailem]

Let me know when you are around Amsterdam ill buy everyone a one new pear of wooden shoes (Klomp)

Ooooo. Careful what you offer. My wife says France/Normandy this summer, but I have heard Amsterdam mentioned in the near future.

Do they provide dance lessons with those (Klomp.. Klomp) shoes.

 

[Stu Jackson]

My wife says France/Normandy this summer, but I have heard Amsterdam mentioned in the near future.

Why not do both, it's only ~450 miles from Normandy (Mt. St. Michel) to Amsterdam. Lots to see along the way, too. You know, "While you were there..."