Low rpm after warm-up

[Bobby Prat]

My Yanmar 1GM will start and run fine for about 2 minutes, but then loses power to the point that the max rpm is about 2000. This will happen with or without a load (in gear or out). Anyone else experienced this? I didn't find anything by searching the archives, but maybe I wasn't using the right keyword.

 

[Craig]

Maybe filters ?

I would change your filters first. We had a power shortage and changing both filters fixed it.

 

[Ken Palmer]

Blocked fuel tank vent

Make sure the vent to the fuel tank is clear. It is possible that when you run your engine with a blocked vent, a vacuum is built up causing restricted fuel flow.Ken Palmer, S/V Liberty

 

[Bobby P.]

Closed Fuel System

Ken, The system is a closed loop system I thought, Anyway it has a return.

 

[Paul Akers]

Bleed the fuel line

This will happen if the fuel line need bleeding. Try bleeding the line while it's running. That happened on my 3HM.

 

[Jock Muir]

Check your fuel filters and line.

Your fuel filters, there should be two of them, could be dirty. The Primary filter usually will accumulate excess water that must be drained out. Also check your fuel line, it may be dirty. Also, is your air filter clean? There are diesel fuel additives that help to clean injectors. Try a truck stop or auto parts store.

 

[SteveC]

If you still have the problem....

I had a similar problem many years ago. If you have tried the other suggestions and still have the problem, take a look at the fuel pickup tube in your fuel tank. There usually a small screen that is supposed to prevent sediment from entering the line. This can become clogged and starve the engine. When the engine stops, the sediment falls off only to be picked up by suction when the engine is started again. I removed the screen on mine, preferring to have it trapped by the first filter where I can get to it.