330 loses power

[aledobud]

I have a 1986 330 with the Yanmar diesel. Great little machine, but lately it starts losing power and sort of chugging at full throttle after about 20 or 30 minutes. It idles fine. I have thought I had it figured out a couple of times but still get the symptoms. I have cleaned out the fuel tank and the little fuel strainer, replaced the fuel filter, air filter, fresh fuel and bled the injectors. Since it happens after running a while, it could be the head gaskets, but before I go down that road is there anything else to check? If it is the head, where to get parts?

 

[Kish318420]

Besides John Deere

There is Yanmar Genuine Parts | Yanmar USA

Also Amazon, eBay,

But you will need part numbers, so use the JD parts site. Do you have TM and CTMs?

 

[Dave M7040]

I have a 1986 330 with the Yanmar diesel. Great little machine, but lately it starts losing power and sort of chugging at full throttle after about 20 or 30 minutes. It idles fine. I have thought I had it figured out a couple of times but still get the symptoms. I have cleaned out the fuel tank and the little fuel strainer, replaced the fuel filter, air filter, fresh fuel and bled the injectors. Since it happens after running a while, it could be the head gaskets, but before I go down that road is there anything else to check? If it is the head, where to get parts?

Way too soon to be thinking head gasket!!
How does your diesel fuel get pumped from the fuel tank to the filter(s) and injection pump? Sometimes a mechanical pump on the side of the engine and sometimes an electrical one in the fuel tank.

Perhaps as it is used your fuel delivery to the injection pump drops off and you only have enough fuel being supplied to the injection pump to idle or run poorly.

For troubleshooting, some people have used various methods to provide fuel directly to the injection pump in a way which by passes the factory pump. A mustard squeeze bottle full of diesel and connected to the injection pump, an electric pump installed to feed the injection pump from a can of diesel. A boat style squeeze bulb and a boat outboard gas tank so you can attach this setup and hand pump fuel to the injection pump to see if it solves the poor running.

Dave M7040

,

 

[beenthere]

Look into the fuel pump for the 330.. ( key #4) apparently a sub is AM876266. $250+ on GreenPartsStore, $110 on Amazon, and several other electric pumps listed with that part # for less than $25. No idea if they do the job, but may be worth looking into.

 

[tonyq60]

There is an electric lift pump on left side of engine down at the rail.

It looks like fuel filter.

When hot check it.

How?

Perform priming or bleeding when cold and observe how much flow as well as exact amount the bleeder is turned.

When acting up shut down and retest and compare outputs

Do not start changing things first as you need to see something broken.

The fuel pump is floating in the hose so it requires both hot and ground connections and one could be flaky.

It also may consume more fuel when warm and fuel supply not enough.

Possible to add pressure gage to the output side of filter to monitor pressure as well but that more effort.