743 low power syndrome

[mibh1]

Runs for hours normal power, then limps along at about half RPM. In a modern gasoline vehicle I'd suspect fuel pump or fuel filter. What are the common causes of this syndrome in a 743?

 

[Tazza]

What colour is your exhaust?

 

[mibh1]

Grey, like my 864 and other diesels here.

Also the rest condition includes waiting for the engine to cool down to ambient temperature.

Does not burn or leak oil or coolant.

Unreliably, it most often runs all day, and only occasionally drops into this low power mode after a couple of hours.

 

[foton]

to me it sounds like a fuel delivery problem

 

[ByggareBobby]

Something (filler filter?) on the bottom of your hydraulic tank that is loose and blocking the oil to your pump now and then?

 

[mibh1]

Thanks to the advice on this thread I studied fuel starvation on YouTube and found it upstream of the fuel filter. It's running well for the moment after some compressed air to clear the fuel pickup, but I now know I have to drain and clean the tank itself. It's a 1981 machine and there's got to be a lot of debris in there.

A heartfelt thanks to all.

 

[mibh1]

This jam was from bits and pieces of the sheath around the fuel sender harness.

 

[ByggareBobby]

I'm currently cleaning up and fixing my newly bought old 643. Disassembled the diesel and hydraulic tanks yesterday. This is what I found in my diesel tank ;-) Lots of small pieces of old hoses and both screen filters were rattling around lose at the bottom. My motor did not stall or show any odd symptoms (checked compression) but the lift and tilt seems weak so I took the decision to refurbish as much as possible including repacking all cylinders. Maybe half way through this work by now...

 

[hoardac]

I'm currently cleaning up and fixing my newly bought old 643. Disassembled the diesel and hydraulic tanks yesterday. This is what I found in my diesel tank ;-) Lots of small pieces of old hoses and both screen filters were rattling around lose at the bottom. My motor did not stall or show any odd symptoms (checked compression) but the lift and tilt seems weak so I took the decision to refurbish as much as possible including repacking all cylinders. Maybe half way through this work by now...

That is quite a collection.

 

[DirtRodeo]

I found not one but two hand fulls of sediment in my mid 80’s diesel tank. Need to tackle the hydraulic tank next. It had a rag instead of a cap when I bought it.

 

[laurencen]

couple years ago had a similar issue on a 743 turned out to be a seed, it would suck up the tube and get caught in the elbow, sit for a short time it would sink down the tube and run fine for a short time, when we cleaned the tank there was several in the bottom with other debris but the seeds were the culprit, one was still in the elbow