Started the truck today. Drove about a half mile with very light throttle then truck went real quiet like it had lost 20* of timing and a noise from the pump sounds like running the end of a straw over bicycle wheel spokes.

When I push on the accerlator quickly at idle it pops and misses and puffs white smoke.
If I turn on the KSB solenoid switch it puffs black smoke as usual and sounds normal.

Think something became dislodged in the fuel system and ended up in the pump?

Anything else?
Where to start looking/testing?

Thanks,
Kurt

 

The noise does not sound like a happy noise.

Maybe pull the pressure regulator valve out and look it over before you yank the pump.

 

Pressure regulator valve?

Drove it into town (I probably should not) and seems to be getting some of the louder "diesel rattle" back.
At about 20% throttle it seems to take a quick jump from what feels like 5% throttle to 20%.

Engine is still pretty quiet (muffled?) compared to normal.

It just feels like it lost a bunch of timing.

Any way something could slip?

 

Unless the nut holding the pump gear to the pump shaft loosened up, allowing the shaft to mash up the woodruff key and spin some, that could screw your timing up. Or the lock washer under the nut failed and same thing. That would be the easy troubleshoot. Pull the oil fill tube, look for a half lock washer. Then remove the nut and check to see that the woodruff key is still intact in the pump gear keyway.

 

The pressure regulator valve is the little dingus up on the top front of the case that the little line from the KSB runs to.

 

Removed the valve but, what am I looking for? Saw one very very small metal shaving stuck to the valve when removed but, it could had been from the threads.
Looks like there are 5 holes in this. Two larger ones near the top that come in from the sides, 1 small directly in the bottom and two tiny ones near the bottom on the sides.
I shot brake cleaner through the top ones and it shoots straight out the bottom hole. This normal?
O-rings look good.

Pump gear nut, lock washer and keyway look ok.

I am going bar the engine over a couple of turns to watch the valve train then reinstall everything without the fan and start the engine so I can hear any other noises.

 

Checked pump timing.
Before, the pump tool would start to move the dial indicator around 21* BTDC (I have a timing tape) and end at 2.15 mm with the engine at TDC (when the pin is engaged).
Now it starts to move the indicator around 19* BTDC and is only at 1.62 mm at TDC.
Pump does not seem to have moved.

Something happen to the cam plate?

 

Sounds like with the metal shaving you found, and the timing, that maybe you've started wiping the lobes off the cam plate?

 

Sounds like a likely hypothesis to me.

 

Update; Pump shop says I broke the wristpin in the timing piston. They replaced only that part and stand tested pump and said It was putting out 250 cc at lower rpm and 200 at the high end. They are trying to coax some more out of it before I put it back on. Need to get ready for Denvers Truck Fest in 9 days.