Diesel engine question

[DreamBoat]

The Yanmar 12HP diesel in my 1982 H-30 is being difficult. I cranked it two weeks ago, and let it run at the dock for about 30 minutes, just to "exercise" it. When I shut it down, it would not crank again, and still will not crank. I know there is fuel, I can smell it. I have tried diesel starting fluid (ether) in the air intake. I have tried hand-cranking, so I know it is getting compression.
Does anyone have any ideas?
I have had the boat for four years, and it always cranks, but now it won't.
Please help!

 

[Paul F]

Air, Fuel, Exhaust

Engines run if they have these three elements – air, fuel, and exhaust. You likely have air. Make sure you have fuel. Check the line. Is the fuel shut-off valve open? If the line looks alright open the fuel line just before the injector and see if fuel is pumping out. With an old engine you may have air in the fuel lines and need to bleed the air out and you may have to replace old fuel hoses. Has the exhaust elbow been checked lately? It may be plugged and without exhaust the engine will not start. This will take some time to remove the exhaust but if you feel that the air and fuel are o.k., then this is the next step. Here is a link to service manuals that you can download http://www.motoren.ath.cx/menus/yanmar.html
I had a similar problem with my old 2qm15 engine. The fuel lines in these older engines are hard to bleed. A Yanmar mechanic gave me this tip – if the return fuel line goes back to the fuel filter change it to return to the fuel tank. This cleans the line of air instead of it recalculating back to the injector. Also make yourself a start switch that you can use at the engine. It will make all this work easier.

 

[kair]

Fuel Bleed

The most common issue is fuel bleed. Check that the fuel is getting to every segment and bleed the air from all segments all the way to the injectors.

I had the same problem when I changed out my fuel lines. I had to bleed the lines at each segment methodically from the tank to the injectors and after that all is well.

Also check the most obvious first, fuel cut off valve at the tank outlet.

 

[Beau16545]

If the diesel fuel is old, even if you've been cranking it on a regular basis, it will grow organics and which will eventually foul the injector and cause problems. A fuel stabilizer will fix the storage problem but if this is the problem you will need to clean your fuel system. Be careful about spraying too much starter fluid in a diesel engine. It increases the compression too much and causes dislodging of the rings which can cause a multitude of problems. Try draining all the old fuel cleaning the system and putting in fresh. Of couse you'll need to bleed the system as mentioned above.

Good Luck

 

[dbecker68]

Thanks for your ideas

I

 

[dbecker68]

I know it's hard to troubleshoot this kind of problem without being there. I will try these ideas and report back. I just hate to call a mechanic. Since I keep the boat at my house, it costs a ton just to get him to come out.
Thanks again!

 

[Nelsonhow]

Before you get REALLY nuts

Assuming that you have fuel in the tank... Most inboards have a fuel cut off valve in the fuel line between the fuel tank and the big filter mounted on the bulkhead. Make sure that the valve in in the ON position . Usually the handle has to be in line with the fuel lien. I bet someone turned it off or you threw something on top of the tank which flipped the valve to off. If you sucked the fuel dry you'd need to bleed the motor. Get the Yanmar instructions, it's not hard but it is a pain.

 

[dbegonia]

Won't Crank or won't start?

For me, the key phrase is "won't crank", which is different from "won't start". Unless there's clarity to this question, it's kind of hard to start doing the diagnostics.

However, you did say that you tried using diesel starting fluid, so I assume that the engine cranks. But then again, this IS just an assumption. Without clarification, it's really hard to proceed on suggesting what might be the problem.

 

[Benny]

Most diesel engine maladies can be traced to fuel.

Clean or replace water separator filter and replace primary fuel filter then bleed the air out of fuel lines and crank away. Yanmars rely solely on compression to ignite diesel fuel so they may be somewhat slow to start in cold weather. Make sure batteries are fully charged and connections to starter are clean and tight. With the oil being cold cranking speed may be somewhat slow but excesively slow crancking may not allow the engine to start and could be traced to a bad starter or weak batteries. Good luck.

 

[BoatlessAfterKatrina]

I may be late to the game here...

The Yanmar 12HP diesel in my 1982 H-30 is being difficult. I cranked it two weeks ago, and let it run at the dock for about 30 minutes, just to "exercise" it. When I shut it down, it would not crank again, and still will not crank. I know there is fuel, I can smell it. I have tried diesel starting fluid (ether) in the air intake. I have tried hand-cranking, so I know it is getting compression.
Does anyone have any ideas?
I have had the boat for four years, and it always cranks, but now it won't.
Please help!

...but since I didn't see a follow-up by the OP, I thought I'd chip in.

If indeed the problem was that "it would not crank", I had a similar problem with my 2qm15 on my Irwin. I tracked down all the electrical, including the fuse on the line coming from the key switch. It turns out it was the fuse holder that was the culprit. When I removed the fuse, I was able to draw current through it - so I erroneously ruled out the fuse. The wires connected to the fuse holder had become corroded and one had barely fallen out of place. This probably happened as a result of engine vibration - which seems to be at its maximum when at idle, and which is precisely where the OP had left it, idling for an extended period of time.

That said, I've always heard that it's better to put a load and increase rpms when running for extended periods; ie, I don't idle for longer than about 10 minutes. After all, the manual states that after about 3-5 minutes the oil has reached all the critical parts.

...oh yeah, and it just may be the fuse.

 

[dbecker68]

Many thanks for your help.

Thanks to all of you for your input and your ideas. I finally had to get a mechanic out, and he found that one of the washers in the fuel line had a "crease" in it, which was allowing air in and fuel out. I'm not mechanical enough to find thesse kinds of things.