cummins nta855G4..problem

[AKL]

Hi guy..I need help on some issues
1.the overhead setting...my plate say TS ZERO INCH
Lash and i have a STC INJECTORS...

2.Its a 300kva Genset and when the Genset is loaded it will run for about 30 min and the RPM will start to drop gradually until 1300rpm..

3.I have change fuel filters,actuator,controller, mpu..cleaned fuel tank

This happened after I change head gaskets because it was leaking..no abnormal sound when running..

Help me guys...thank you

Eng s/no:23238234 cpl 1436

 

[Neily]

Hey mate, haven't got my cpl book handy atm but...
You sure it's an stc engine? It's pointless having stc on a genny. What's the fuel pressure doing while it's running fine and while slowing down?

 

[Neily]

Ps my comment on the stc may be off, just wouldn't of thought you would have step timing on an engine that runs at a constant speed.

What did you set the overhead at? and why the head gasket replacement?

What are the, actuator,controler,mpu? I have no gen set experience mainly automotive.

If it's running 30 mins before slowing you would have to assume a loss in fuel pressure for some reason, does it have an ordinary mechanical pt pump?

Got some pictures?

 

[AKL]

hi neily,i set the overhead .11 and .23 and 90 inchlbs on injectors
I have change the fuel pump actuator, the cummins engine controller, and magnetic pick up unit..
The head gasket was leaking...so i change it..
yes it has a pt pump but the speed is controlled by the fuel pump actuator...
will post picture later....

 

[Neily]

Yeah settings wouldn't be far off, I'll have a look tonight. We always set them at .14 .27 regardless of what it was suppose to be.

Yeah... What was leaking though, compression,coolant,oil? Reason I ask is you have 3 different scenarios for a head gasket "leak" and as many causes. Irrelevant to you power problem though I would think, just curious.

Did you take the injectors out or leave them in?

I've never realy worked on a gen engines to much so I don't realy know much about the speed control system, I just assumed it would have a variable speed governor like a pump engine for eg but sounds a bit more involved on this one.

 

[AKL]

The leak was oil, I leave the injectors in didn't remove them....I'm currently removing the injector and fuel pump....for servicing
...

 

[AKL]

picture of INJECTORS and fuel pump

I just removed the injectors and fuel pump... Found there are some dirt on the injectors screen...any ideas..?maybe the culprit is found???

 

[Neily]

Yep certainly wouldn't help, gotta be a reason for that to get there though. Should be a screen in the top of the pump you can cheek aswell. I hope you don't have the pump sitting in the dirt after its done up lol.

Some engines have the fuel filter on the back of the pump and some remote mounted. If remote sometimes the fuel hose between the filter head and pump can deteriate internally filling the pump with rubbery goodness.

I didn't get to my books but 105in/lb is what my memory suggests for injector set. I'd check up on that though.

How many hours she done? Looks like the pump has been apart before.

How much experience do you have working on these engines? I'll post a few tips up for ya if it might be of value to you or someone else that might read these posts.

 

[AKL]

Not sure about the hours...but it looks like the pump hasn't been apart.. because it's normal practice to punch the date of service on the pump housing but this pump doesn't have it...I have done a few in the past....I have 15 years experience in overhauling diesel engines.. But I'm new to the fuel actuator and controller stuff....and it's driving me crazy....I hope you could share some of your experience with me....thank you...

 

[Neily]

Hey, yeah pumps probably original just looks like the tamper proof screw has been chiseled out before. I probably don't know anything you don't anyway lol, I have no idea about the speed control system on that so I can't help ya there. Usually a good idea to fit some new o-rings on the rocker shafts while ya have it pulled down that much, very frustrating when it runs a while than leaks and it all has to be pulled down again. Mainly if there been there a long time.