isc fuel pump and stumble

[Signature620]

What's weeping from the gasket, oil? And which gasket - The main fuel pump mounting gasket or the gasket between the main pump and gear pump?

These C series common rail pumps have those lovely ceramic plungers that end up fracturing. They aren't as disastrous as an ISX when they fail but they are quite easy to inspect. Just undo the four 12 point bolts holding the head on the pump and remove it. Pull the retainer springs off by hand and inspect the plungers for scuffing, cracks or fractures. Also push the plungers in quickly by hand - They should sort of bounce back at you. If they slip straight in and out without resistance then they aren't sealing - Replace the head.

Also check if there's fuel leaking from the weep hole on the gear pump (rear section) of the pump.

If the engine has done 10,000hrs or more then just get a whole changeover pump.