656D Running Rough

On the return line, I got some air and fuel out when I first bled the pump, but now I get almost nothing out of the return even when running. Is this normal? Not sure what to look for when you say check for chunks of flex ring.

My injection pump man is the best around, but he's old, and I have been considering taking the pump back off and sending to San Antonio to get it checked.

Thanks very much for any suggestions you may give. I'm a youngster and could use all of it.

He's always been great with dairy cows, but lousy on the mechanicals.

Or, does it just plain miss all the time?

Allan

I had a retired diesel mechanic overhaul the pump, I have alot of faith in him but it could be he got something wrong, he is pushing 85 years old.

I have recently changed the fuel filters and have not found any water in the fuel. Any suggestions you can give me would be greatly appreciated, I'll try about anything.

Thanks-

Your symptoms sound just like you've got it advanced too far.

Back 'er up the width of a pencil mark and see if that helps.

I used to always advance 'em about 1/64" in the wintertime to make the dudes start easier. Downside was that when spring comes, they do just what you are describing. Surging and blubbering with that grey smoke at high rpms.

Hope it straightens out,

Allan

When I get off work tomorrow I'm gonna check the time again, then which way to I need to turn the pump to "back'er up the width of a pencil mark"? Rotate top of pump toward the engine or away? I may go both ways and see if either helps.

Also, should I get fuel out of the return line at all times? Seem's like sometimes I don't get any at all.

There is a charge pump on the end of the pump where the fuel inlet is. The pressure developed by that pump is responsible for filling the charge pistons in the high pressure chambers and is also used for timing advance. A restricted return will cause loss of fuel delivery because the high pressure pistons will not fill properly and will also cause the pump to not advance with higher RPMs. You pump mechanic probably has a timing window he can put on the pump to check for sure the advance is working.

I have changed many of these flexible rings and it is a relatively simple procedure, but you must have a good working pump to start with. If there are any other problems with the pump it is best to have a pump shop do the work. I have rebuilt them in the shop but you have to have a good working tractor engine, dynomometer, flow meter, and timing window to do it properly. If you are lucky you can do a good job in only about twice as much time as shop with a pump stand.