Help for a friend

[Blown284]

Have a friend at the same marina as me with searay (believe it's 410 or 420) with cummings. Anyway, he indicated that one of his engines has, what he describes, as a sputter or hesitation. He indicated that it doesn't always happen so it's sporadic.

I asked him the following questions:

* Any obstructions on the props? (he answered no)
* Transmissions fine that you know of? (he answered yes)
* When is the last time you changed your primary filters? (last season)
* When is the last time you changed your secondary filters? (last season)
* Where did you get fuel last time around? Notice water in the fuel? (I got the "i don't know look")
* Do you add any type of addictive when you fill up? (I got "no").

My question to the more knowledgeable diesels here is ... am I on the right track? I openly admit that I"m still learning diesels (have a diesel car, truck and boat).

Thanks!
Tim

 

[HP12Sea]

Not that knowing the model engines, year, hours, etc. isn't helpful, but couldn't hurt.

My vote is for fuel pump or injector then possibly electrical. I'd redo all the filters first on that motor but probably not that since other motor ok.

 

[mquiet]

Is it sputtering under load or at the dock. Drain rancor and check for water. Then replace filters, then it gets more expensive.

 

[Blown284]

Is it sputtering under load or at the dock. Drain rancor and check for water. Then replace filters, then it gets more expensive.

Sorry, I forgot to add that... he was underway at approx 1900rpm. What he noticed was it would stay at 1900rpm, then dive to 1700rpm then back up.... be fine for a while and for no reason, do the same thing again 1900, 1700 ....

 

[bobeast]

Sorry, I forgot to add that... he was underway at approx 1900rpm. What he noticed was it would stay at 1900rpm, then dive to 1700rpm then back up.... be fine for a while and for no reason, do the same thing again 1900, 1700 ....

That sounds a whole lot like a fuel pressure issue.

 

[Blown284]

That sounds a whole lot like a fuel pressure issue.

I agree which is why I couldn't help think maybe filters are clogged

 

[JHornsby3]

This might be reaching but if the fuel goes to one engine before the other, it could have some bugs in the fuel line. I have had the same type of thing in a pick up and had a batch of fuel that had algae or bugs in it. It was small enough to get past the Raccor filter with IIRC 12 micron filters on. That was when I started putting a pint of 2 stroke oil in every tank of fuel and it helped. It along with Lucas every few tanks sure made a big difference. The independent study done said the 2 stroke helps lube the injectors and well as help keep the bugs from growing. And I also noted a gain of 2mpg on my 6.5l GM motor. The algae will be a gray to dark gray color in the filters when you cut them open.

John