I think I have the wrong ij pump on my 94 6.5. ss diesel site says that they won't iterchange. how can i tell which one belongs on my truck.( vin?) this one is new and definitly has a problem. (new GM installed) changed pmd. thanks, roger

Is your truck HD or LD? half ton 1500 would be light duty, one ton 3500 would be heavy duty, 2500 could go either way. Does your truck have an EGR valve on top of the intake? Then its a LD and should have a 5521 pump. If not, its a HD and should have a 5068 pump.

If you have a 5068 pump where there is supposed to be a 5521, then the truck will be hard to start, smoke heavy black under load but have tons of power, and also hunt for idle speed, engine surges up and down. If you hook a scanner up, your Low Idle fuel rate will be VERY low, like 0-2mm.

If you have a 5521 pump where you should have a 5068, then you usually get white smoke and low power, also hard to start and may stall (underrun) when shifting into gear. The scanner will show a high LI fuel rate, nearly 20mm.

Thanks for the info diesel guy.It is an HD should have a 5068 on it. will other # pumps work on this motor. It does have a 5521 on it and all of the symtoms you listed. thanks, roger

You can always buy a '95 F prom and it will work. Dealers sell them for $40- $70 usd but you have to have the prom code (I have one for auto tranny).