I have a Yanmar 20hp 3 cylinder diesel with 1250 or so hours. It has started to run very rough - stumbling, not wanting to rev, surging. It did this last fall and I changed the fuel filter and bled the fuel system and checked for water. It ran well afterwards so I thought my problem was resolved. Last weekend I cranked her up (busted right off) and used it 2 hours with no trouble when the problem came back. It will crank up but shudders very bad and will not rev up. Last fall it would crank up and run varying lengths of time before acting up. I need to be pointed in the right direction. Thanks a lot for any ideas.
Diesel engine problem
- Thread starter kudzu04
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davesl708
Elite Member
Others may know better but I would start with the fuel injectors.
GManBart
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It sure sounds like a fuel problem. Since it's happened more than once, I'd drain the tank, and make sure it's clean. Then I'd disconnect all the lines to the fuel pump, fuel filter, injector pump, and injectors, then use compressed air to make sure they're clear. After that, I'd replace the fuel filter, fill the tank, bleed the lines, and see what happens.
RPW
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After that you'll be looking at injectors and then injector pump.
Billrog
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What's been said and check the fuel pick-up is clear.
davesl708
Elite Member
All of these steps can be done at home if you are inclined. Parts or Shop manual is very handy.
GManBart
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Generally speaking, injectors and injector pumps are not serviceable by people without the right training, equipment and tools. I've overhauled many engines and restored cars, but I wouldn't mess with injectors/injector pumps except in a dire emergency.
The good thing is that those are the two least likely problem ares. Injectors can often be replaced for around the cost of cleaning and adjusting them. The set (3) I bought for the Perkins in my dozer ran only $150.
NorEaster
Member
Before you start throwing parts at it-
Drain and clean tank
Blow out supply and return fuel lines
Replace fuel filter
If it has a block mounted lift pump clean the pre-screen out.
Past that you can have the injectors pop tested to see if any are outside of spec, a diesel fuel shop can do it, I believe JD dealers can as well.
Drain and clean tank
Blow out supply and return fuel lines
Replace fuel filter
If it has a block mounted lift pump clean the pre-screen out.
Past that you can have the injectors pop tested to see if any are outside of spec, a diesel fuel shop can do it, I believe JD dealers can as well.
holzboat
Bronze Member
How old is the tractor? Sometimes the fuel hoses can start to break down and cause problems that are not visible.