Yanmar Won't Start

[lehighsail]

Finally got to the boat to commission for spring. My engine won't start (Yanmar 3YM30). The starter works when the key is turned but as soon as the key is released the engine stops. Changed the fuel filters. I bled the fuel lines out the top of the secondary filter and seems OK. However, when I pump the fuel pump no fuel comes out of the end of the small diameter tubes that go to the cylinders when I tried to bleed them.

Am I forgetting something? Any suggestions would be appreciated.

 

[kloudie1]

Bleed from secondary filter to the HP injection pump. Not familiar with your pump, but if youo just crack/loosen the fuel fitting at the pump inlet you should be able to pump fuel out there with the finger pump. Tighten after you have no bubbles there and it should start. then, with engine idling, crack each HP connection in sequence at the injector.. engine should slow and "miss" tighten back up and it should return smooth. do each in sequence, not at same time.

 

[Chris Patterson]

You could pump for a week and nothing will come out of the high pressure lines. The only time fuel will come out of either end of them is when the engine turns over.

 

[Claude L.-Auger]

You could pump for a week and nothing will come out of the high pressure lines. The only time fuel will come out of either end of them is when the engine turns over.

Chris has a good point. If engine won't start, it's easy to make engine turn over on starter power alone: decompress all 3 cylinders and crank engine with starter. It will not start but will run the fuel pump with enough pressure for you to bleed. Good luck

 

[Jake N Eggs]

Chris has a good point. If engine won't start, it's easy to make engine turn over on starter power alone: decompress all 3 cylinders and crank engine with starter. It will not start but will run the fuel pump with enough pressure for you to bleed. Good luck

Claude, the YM engines do not have decompression levers.

 

[Benny17441]

Make sure the engine stop cable or switch is in the run position. Make sure fuel is free flowing to the lift pump. A clogged fuel pick up tube or tank vent line could be obstructing free flow. Use the engine starter to turn the engine and facilitate bleeding air from the lines. Both the lift pump and the injector pump will try to build fuel pressure to displace air. If your engine exhaust port is below the water line do not crank the engine continuously for too long as it could draw water into the cylinders; do it in short pulses after allowing for recovery time in between sessions. Open the bleed screw at the secondary filter first and wait until fuel squirts out of it with no bubbles before closing. Then open the bleed screw at the injector pump and again wait until fuel squirts out with no bubbles before closing. At this point you should be good to go as any remaining air will be pushed out of the injectors by fuel pressure. Once you have fuel delivery then you need air and compression. Make sure the air intake tube is not clogged. Compressions at starter crank speed is built up gradually by successive revolutions. it is important for the engine to turn at a high enough speed for it to build up and sustain the necessary compression and for that the starter should be in good operating condition and the batteries adequately charged. I wonder how come your engine may have allowed air into the lines and it is an explanation that may need to be figured out but concentrate on getting the engine started first. Oh before I forget the condition of the fuel is also very important as bad fuel will not fire. Check your fuel for freshness and lack of water. Also check your engine oil level and viscosity. Remember we have a suspected fuel leak somewhere which let air in the fuel lines to begin with. Sometimes a pin hole in the lift pump diaphragm can leak a large volume of fuel into the crankcase diluting the oil and raising its level. Chances are you just need to bleed the lines and start from there. If nothing happens within a month where air gets again into the lines it means any leak is so small that it may not be worth continuing to track.

 

[DougM]

Claude, the YM engines do not have decompression levers.

I beg to differ.... Either that or I am wrong about the two levers on the side of my 2GM....

 

[lehighsail]

Thanks to all for the suggestions. Problem was that there was no fuel getting to the cylinders. I followed the suggestion of first cracking the line to the IP and then each of the pipe ends at the cylinders and guess what? It started right up...but you knew that.

Thanks again to all. I have printed these posts and will put them into my onboard manual. Should this happen again during the season, I will look further for a possible air leak as Benny suggests.

P.S. I have to agree with Jake & Eggs, after looking in my 3YM30 parts catalog and staring at my engine for 30 minutes there are no compression levers.

 

[kloudie1]

Great news, Lehigh.. glad ya got it!

The 3YM is one of the new (fangled) Yanmars.. no decompress levers and it does have glow plugs..

 

[mz4wheeler]

I have to agree with Jake & Eggs, after looking in my 3YM30 parts catalog and staring at my engine for 30 minutes there are no compression levers.

How do you stop the engine? Do you pull a cable? [hint]

 

[kloudie1]

Shoot.. those are so sophisticated that ya just turn off the key to stop 'em..

 

[BigEasy]

That's interesting that you had difficulty starting the engine after bleeding thru the engine mounted secondary filter. According to the 3YM30 operating manual, once you have bled the secondary filter, there is an "automatic bleeding device" that is supposed to bleed the remainder of the system. I don't have a clue what this device is or where it is located; however, it is mentioned on page 26 in the operation manual. I have never had any problems bleeding my engine; however, it has never sat unused for any length of time. Glad to hear that you got it going again.

 

[Claude L.-Auger]

Claude, the YM engines do not have decompression levers.

I was not aware of that. Thanks for setting me straight.