I have a question about a diesel engine in a mini excavator we have at our rail road museum. I'm told it has a 3 cylinder Mitsubishi diesel in it. After it runs for a while it quits easily and won't stay running when you start it until its had time to cool down a bit, then it starts up and runs fine for a while again. When it runs it runs great. When it won't stay running it acts like its not getting enough fuel. Seems like if it was a fuel filter it wouldn't run again until the filter was changed. I did see today it has a filter like people put on gas tractors coming out of the fuel tank when they replace the sediment bowl assembly. I know that can create a problem on a gas tractor, can it be a reason for our problem? Seems like something is getting too warm and causing a problem. Everything is under a hood so not open like a tractor engine would be.
- Thread starter Charlie M
- Start date
Traditional Farmer
Well-known Member
- Location
- Virginia
Probably something in the tank restricting the fuel flow.
Tx Jim
Well-known Member
- Location
- Coyote Flats, Texas
I suggest to install a new filter & check for good fuel flow from tank to inj pump. It's also possible that the tank isn't venting creating a vacuum in tank restricting fuel flow. Try operating with shop towel covering fuel tank neck.
Steve@Advance
Well-known Member
Is there a lift pump between the tank and the injection pump?
If so check it like you would a gas fuel pump, but plug the line going into the injection pump so it doesn't get air in it. Disconnect the outlet line, spin the starter, see what it pumps. Catch what it pumps, look for water.
Is there a return line to the tank? On some systems, if that line gets clogged they will act like what yours is doing. Usually a clogged return is the result of something failed in the pump and sent plastic or rubber down the line.
If so check it like you would a gas fuel pump, but plug the line going into the injection pump so it doesn't get air in it. Disconnect the outlet line, spin the starter, see what it pumps. Catch what it pumps, look for water.
Is there a return line to the tank? On some systems, if that line gets clogged they will act like what yours is doing. Usually a clogged return is the result of something failed in the pump and sent plastic or rubber down the line.
showcrop
Well-known Member
Classic reduced flow. It gets plenty to run at low speed, but it runs short after a little while at higher speed. After getting a break the low flow will refill the filter and chamber in the pump so the cycle starts over. The most likely obstruction is the filter. Try breaking the fuel line at the pump and catching the fuel to see if it will fill a pint in two minutes. if not open it after the filter and test, then before the filter and test. step by step until you isolate where the obstruction is. It is usually mud.
Billy Shafer
Well-known Member
Is the radiator clean and letting air pass. I say this because I was called to look at a main engine. On a large RV unit. They had replaced the fuel filter,fuel lines and fuel pump. I noticed their was very little air coming out. Radiator fins were covered in trash.We soaked the fins in cleaner. Then washed them out. Ran fine after that.
Farmer Rock
Member
If I am understanding correctly, it won't start easily when hot, and loses power at higher rpms? If so, that sounds like a bad injection pump. To verify this,next time it won't start up right away when hot, pour cool water over the injection pump, and if it starts right up, that is you problem. I would first look and make sure the lift pump is good like Steve suggested.
Rock
Rock
the tractor vet
Well-known Member
That my boy is the fastest way to end up buying a NEW INJECTION pump and many before have done just that . Not intentionally but by accident . A guy out plowing and see's he is running hot so he runs down to the milk house and grabs a garden hose to flush out the fins on the radiator and the stream of cold water hits the injectorn pump and in a split second the pump seizes locking up the head and twisting the shaft off .NEVER tell someone to do that as it could cost then over a grand for that stunt.
the tractor vet
Well-known Member
While not up on Mini excavators it is a diesel engine and like our skid steer that has one of them thar plastic fuel filters it was also have a second filter SOME PLACE , But by all means change it and look for the other filter DO NOT run COLD water over the injection PUMP You will end up with a 7500 or more pounds of Scrap.
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