I'm looking for some ideas to figure out the problem with my truck. Just got back from a long drive and it's idling very rough, almost missing it sounds. Idle does not drop low like a worn pump, bring the rpm up and it runs smooth. Applied 12 V to KSB solenoid and no change. Pump is new (only 1100 km on it) All I,ve done to this one is put a trimmed 354 (4200 rpm) spring in it. I pressured up the fuel tank and no fuel leaks anywhere. Starts great even without the grid heater at 5 C. I was going to try advancing the pump but the KSB doesn't change the Idle condition so I'm not sure if that will help. I'll also check the lift pump pressure (It was new with the injection pump) Need some help here. I may need injectors, seen this problem on a 24v. This engine has 620,000 Km.

 

No ideas anyone???

 

If its running smooth while cold but after extended running it idles rough, I'd check the return fuel line. If your return is plugged then your pump will start to run very hot, which will only be seen after running for awhile. Even if return flow is severly choked down the pump will not have adequate cooling.

The pump isnt going to last long if no return in the problem, so check it out as soon as you get a chance.

 

ive seen tired injectors do that when hot. have a shop re pop, may need new nozzles.