Regular Contributor

Re: C9 HEUI question.

The entire HEUI pump housing acts as a reservoir for oil supply to the high pressure pistons. The supply oil is stored within the HEUI pump housing when engine is stopped. As the oil from the engine oil lube pump enters the pump housing at the top of the housing the only way oil could drain out with engine stopped is through the front shaft seal. There are check valves in the high pressure pump outlets to hold the oil in the high pressure circuit. The fuel transfer pump has an internal safety relief valve and priming bypass valve however problems with these should cause fuel pressure issues.

New member

Re: C9 HEUI question.


I'm suspisious of the HEUI pump.  Is there a check valve or something in the pump that might allow fuel or hydraulic oil to drain back that would throw fuel delivery off? This is real disgusting exposure.

Trusted Contributor

Re: C9 HEUI question.

make sure that the technician who attends, cleans the Heui gallery in the cylinderhead.

it happens alot that the bearings fail in the high pressure pump.

the chips damage the injectors and cause them to leak.

a lot of times only the injectors and pump are changed and after a few months the problems with the injectors start again.



Re: C9 HEUI question.

Thanks for your direction.  Tech was out from Fabick Cat this week.  Connected laptop and ran tests at dock (650 rpm & 950), at cruise (1800) and back at dock (950).  Results were injector #6 questionable.  Will have Fabick proceed with improved HEUI pump and injector #6 and do the work May, 2019 after spring launch.  

Regular Contributor

Re: C9 HEUI question.

Is there white smoke in the exhaust when started cold ? It may be a injector that when the engine has sat for while dribbles or leaks a small amount of diesel into the cylinder. When the cold engine is started the diesel fuel sitting on top of the pisto can create a diesel knock, does not combust fully and is exhausted out the cylinder into the exhaust and this raw diesel is what you seen on the water.

Super Contributor

Re: C9 HEUI question.

There was an improved HEUI pump introduced in 2013. Part number 20R1636. This pump will require other parts to install as the pump is around .5 inch longer. Your local Cat dealer can provide the necessary parts. Refer to special instruction REHS7947.

C9 HEUI question.

CSN000792  Stbd - HEUI pump & injectors replaced at 300 hrs.

CSN000793  Port - Original.

Build year 2004.  Current hours 900.  


Concern is with port engine. 


Symptoms are fuel on water, knock on start-up and misfiring, running rough for minutes.  Improves when idle over 1200 rpm and as engine warms up.   Runs fine under load and cruising.


Symptoms occur at spring start-up, after setting for three weeks and after oil & filter change.  Warm engine start-up and short time setting start-up is fine.  Oil samples are all normal.  No fuel in oil.


I'm suspisious of the HEUI pump.  Is there a check valve or something in the pump that might allow fuel or hydraulic oil to drain back that would throw fuel delivery off?  Or is the HEUI pump wearing that could lead to a pump failure that could also wreck the injectors?


I'm planning a long trip.  I'm thinking it would be proactive to replace the HEUI pump now (approx $2000) to avoid possible catastrophic pump failure and injectors (approx $8000) on trip plus huge inconvenience.


Like the boat and performance is great, except for this occasional start-up issue.


Am I on the right track or not?