Diesel engine question

[LANCE ON CLOUD NINE]

Are you familar with how your hand prime pump feels when it is actually pumping fuel? It may take many pumps before it is really moving fuel. My first time I gave up before I really had enough pressure to purge. In my limited experience, once you have pumped up pressure, they bleed best by just barely cracking the line nut at injector. If you get a lot of air, you might bleed it twice.

 

[Hermit Scott]

Becker-I just completely rebuilt my yanmar 12 horse. When I put it back together, it cranked fine but would not fire. When I Sprayed WD40 in the air intake it would crank up and run on WD40. The fuel system was not properly bled. ANY air in there and it will not inject the fuel. The easiest step to take is to remove the high pressure line from the injector that goes into the head and crank the engine over a few times. If nothing is coming out of the end of that high pressure line, then we can start tracing down the problem. This is not beyond your ability to do yourself.

The high pressure line is very thick steel compared to the rest of the fuel lines. It is probably not rusted through. I said that before after thiking about it, I doubt it has a hole in it. Anyway you would see fuel spraying out while it was being cranked.

 

[dbecker68]

OK, several of you were right on. It turned out to be an air leak in the fuel system. I found that one of the fittings (not a hole in the line) was loose, allowing in just enough air to cause a problem. The solution seems to be check all fittings once or twice a year to make sure they are snug. I knew the engine vibrates a lot. Maybe next time I will be wiser.

 

[William12213]

I think I would agree that the first step is to check the engine stop and make sure it is functioning correctly at the engine. This is a simple check and doesn't cost anything. The engine was running and you shut it off.....so the last thing you did was mess with the engine stop...first place to check

 

[sailaway78]

And the lesson is

This is another perfect example of some on this board who try to make things much more complicated than they are. Last year I ask a similar question. My engine was getting air into the system, after it sat for at least two weeks. I knew what it was, and it would start and run fine when bled. I just asked if there was something I was missing to try to find the leak. Got the same type of answers you got here. Engines do not break major parts just sitting there between start ups. Don't happen. Could but very rarely if ever. Always start with the simplest solution. 90% of the time it will be right there in front of you, and a little thought and common sense will go a long way in solving a problem.

 

[Stu Jackson]

This is another perfect example of some on this board who try to make things much more complicated than they are. Last year I ask a similar question. ...90% of the time it will be right there in front of you, and a little thought and common sense will go a long way in solving a problem.

Could be, but we've noted any number of times that sounds and smells are really hard to diagnose over the internet, and once the question was asked a lot of good input resulted and we're pleased to see that the questioner came back with his solution.

It wasn't right there in front of US, just him, and many questions about the sounds made when "cranking" were not responded to, continuing the "guessing game" for those who came to help.

Common sense? Ha! It's a boat and we've both been here on this board helping out long enough to get a good giggle outta that concept...

 

[sailaway78]

I certainly agree with that

I can certainly agree with the common sense part. But my point was that many here seem to want to waaaaaaay overcomplicate things. Most of the time it is something relatively simple, and just takes some thought. Little diesels are for the most part very, very reliable. There are parts that can and do fail, but first eliminate the little common problems that are more than likely the cause. After that, then start the serious stuff.

 

[garylinger]

Re: I certainly agree with that

A little true story to ram the "simple" point home - Many years ago I restored a 1956 Jeep. One day I noticed that the brake lights (both) were not working. I rewired the thing from the master cylinder to the lights, taking a lot of time, sweat and wire. When done I found that they still did not work. After a LOT of checking and thinking I finally checked the bulbs....Yep, they were both blown. Apparently I did it when I was moving a long log by repeatedly backing into it with the bumper....Moral is - START WITH THE SIMPLE THINGS FIRST AND WORK UP FROM THERE.