Reply
Super Contributor

Re: 3412 HEUI Slow to start

Yes, definitely check for leakage. I assumed that had already been done. Remove all valve covers, run engine at idle and use Cat ET to perform injection actuation pressure test. This raises pressure to maximum. Any leakage is easy to see. There is a specific procedure to follow when installing the oil supply tubes to the injectors. If that procedure was not followed, oil leaks can occur. All seals should have been replaced, including the seal between the 2 sections of the tube.
Contributor

Re: 3412 HEUI Slow to start

Excuse me for dragging out this thread, I agree that slightly longer cranking is not an issue but after engine has been stopped for several days we are having to crank so long that the battery gets weak and the starter very hot, so far it has always caught but we are in very warm climate, I am cooncerned that one day it may not start and on a Yacht with only one engine this is a big problem!

 

It has been suggested to me that I should run the motor with the rocker covers removed to see if there is a high pressure oil leak at one of the injectors? and that I should replace the HEUI pump and injectors? both very expensive options.

 

Runs perfectly once started but previously for over 10 years this engine has always started with less than 5 seconds of cranking, something has changed?

Highlighted
Super Contributor

Re: 3412 HEUI Slow to start

Pre-lube pump is not offered for 3400 series engines. You might be able to plumb a pre-lube pump into the system but it's not really necessary. The longer cranking to start doesn't really hurt anything and it's just the nature of the HEUI fuel system. I'd make sure there are no leaks on the oil supply line to the HEUI pump.
Contributor

Re: 3412 HEUI Slow to start

Would like a backup plan, is there a pre-lube pump available for 3412?

Otherwise could change elbow on top fo HEUI for a tee fitting with plug to enable easier priming?

Super Contributor

Re: 3412 HEUI Slow to start

The pressure will always indicate 270 with engine off. That's the lowest the sensor will indicate. All other pressures are normal. Compensation pressure is good. The oil is simply draining from the HEUI system and it takes the engine oil pump a few seconds of cranking to fill the HEUI pump. Once the HEUI pump is pressurized, the HEUI pump creates the necessary pressure for injector actuation. There is really nothing you can do to lessen cranking time, other than to run the engines more often. I've had to prime the HEUI pump after changing the engine oil. Seems worse with engines mounted at high positive angles, like many sport fishers.
Contributor

Re: 3412 HEUI Slow to start

ECM Serial Number: 9KS01841

ECM Personality Module Pt. No: 2182970-00

ECM Personality Module Date: Jan02

 

Engine Stopped Injection actuation pressure  270 PSI

Cranking only slight pressure increase (276) until engine catches

Idle (700rpm) 1600 PSI

Control Valve disconnected Alarm: "Injector Activation Valve Current Below Normal"

Pressure drops to 700 PSI idle unsteady.

Reconnect Control Valve, idle steady, pressure rises to 1600psi.

 

Is it possible we still have air trapped in the HEUI ststem that is taking time to compress, or oil is draining back to sump?

 

Did catch much quicker this time because it was run yesterday, seems the longer it is off the slower to start.

 

Contributor

Re: 3412 HEUI Slow to start

OK will try that test later.

 

Injectors were removed and re-installed by local Cat tech, all o-rings were replaced. 

Super Contributor

Re: 3412 HEUI Slow to start

With engine idling at 700 RPM, unplug the injection actuation pressure control valve. Injection actuation pressure should be 700-870 psi. This will create a fault code but that can be cleared. If pressure is not within range, the plug in the compensation valve needs to be replaced with a longer or shorter plug (depending on pressure) to achieve spec pressure. This could affect starting. Did you follow the instructions exactly when replacing injectors and installing the oil tubes? This is critical. Any leakage will cause performance or starting issues.
Contributor

Re: 3412 HEUI Slow to start

Yes single Engine is installed with high positive angle.

 

I have ET for monitoring only, will hook up tommorrow to get software, what else should I look for?

Super Contributor

Re: 3412 HEUI Slow to start

Engine software and injectors are correct. Are engines installed at a high positive angle (front up)?