at 230,000 miles I'd expect the IP to show a lot of wear. The pump was probably due to have been replaced with the injectors about 50,000 miles ago but don't expect a magical solution just by changing the pump. The money for a rebuilt pump will only be well spent if the engine is stong so before spending money on the pump run a compression check. If the compression check is good then go for the replacement IP. Your other fixes don't have a chance of succeeding if the pump is bad and a new pump won't fix a bad engine If the engine checks out o.k. a new pump will give you a good base to start fine tuning the rest of the system.

 

I am new but bear with me here.

Remove the 5/8" fuel line nut from the front of the small rectangular thingy (govenor?) on the top of the motor... looking at it from the grill... its left of your fuel filter, dead center, on top of your motor with two wires running into it... one of them when removed will kill your motor...

The fuel line runs into a little 7/16" plug with a back flow preventor built into it... dont know the terminology... but it looks like a reducer plug with a small nozzel that actually goes into the govenor (?) I believe this line to be part of your fuel return system... but allas... im on my first diesel...

Regardless... inspect this check valve for bits of rubber. If it looks like someone dumped coffee grounds into it... then continue on:

Should it have some rubber in it... check the ring from the fuel line to the check valve and ensure it hasnt crumbled... as that may be the source of this crud...

If its fine... the injector pump is crumbling and passing out bits of refuse... and its time...

Either way... if that check valve is full of crud... you will suffer the symptoms described above...

Clean it out. If you dont replace your pump/ring... it will fill again...

It mirrors my experience... but im too cheap and stubborn to get a mechanic to fix my things... so the terminology isnt there....

hope it helps