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hookliftpete · 12-01-2019, **(Subject: isc fuel pump and stumble )**

Folks,

Fuel pump gasket (isc, about 110000 miles) has started weeping, looks like I'll need to replace the gasket, looks easy from the quickserve diagrams.

Does anyone know if this pump is the same pump as the famous self destructing pump on some of the isx's?

Is there anything I should be looking at when I've got it apart?

The truck has an occasional stumble in top gear at the low end of the gear, is it possible its related to the pump weeping or not likely?

Thanks!

Moose · 12-01-2019, **(Subject: isc fuel pump and stumble )**

A little more info would be helpful ie. year and CM??. CAPS I was a decent system until you had a problem. CAPS II is better.

hookliftpete · 12-02-2019, **(Subject: isc fuel pump and stumble )**

Sorry, get questions floating around my brain and forget the rest...2008 Pete, CM2150, common rail setup. Part number on the pump for this engine is 4954361, hopefully it's not one of those that likes to blow up.

Signature620 · 12-02-2019, **(Subject: isc fuel pump and stumble )**

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.

hookliftpete · 12-02-2019, **(Subject: isc fuel pump and stumble )**

(12-02-2019 )Signature620 Wrote: 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.

I'll get my eyes on it this afternoon!! Thank you!!

hookliftpete · 12-02-2019, **(Subject: isc fuel pump and stumble )**

(12-02-2019 )Signature620 Wrote: 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.

So it looks like it is different than I remembered...ha. To my eye, it appears that the pump is leaking on the lower part (nomenclature is not my thing) but not where I had thought. It seemed initially it was leaking at part 23 on the diagram (gasket), but now it appears to be leaking on the front side of part 14, at a bolt that is not named in the parts breakdown (arrow on engine photo). It is definitely fuel. Engine hours are around 5k.

Signature620 · 12-03-2019, **(Subject: isc fuel pump and stumble )**

Buy a new gear pump for it (part 14). Fair to say air is getting in where the fuel leaks are and making it stumble or take a long time to start up.

It's quite simple to change once you pop the hoses off of it. Just 4 or 5 10mm bolts and it's off. You just have to like up the drive key/adapter on the new one and it goes straight on.

hookliftpete · 12-03-2019, **(Subject: isc fuel pump and stumble )**

(12-03-2019 )Signature620 Wrote: Buy a new gear pump for it (part 14). Fair to say air is getting in where the fuel leaks are and making it stumble or take a long time to start up.

It's quite simple to change once you pop the hoses off of it. Just 4 or 5 10mm bolts and it's off. You just have to like up the drive key/adapter on the new one and it goes straight on.

Thank you!!

hookliftpete · 12-13-2019, **(Subject: isc fuel pump and stumble )**

(12-03-2019 )Signature620 Wrote: Buy a new gear pump for it (part 14). Fair to say air is getting in where the fuel leaks are and making it stumble or take a long time to start up.

It's quite simple to change once you pop the hoses off of it. Just 4 or 5 10mm bolts and it's off. You just have to like up the drive key/adapter on the new one and it goes straight on.

New Gear pump is sitting here looking at me, any chance you might know the torque on those 10mm bolts? I can't find anything in quickserve specific for those.