Merc D-tronic 7.1 L can't get to high rpm

[rustyscrew]

We ran out to the fishing grounds (30 miles) at about 15 knots and then trolled all day (14 hours). On the return leg we couldn't get the RPM's over about 1500 giving us a speed of 8 knots. It would run fine at 1500 but if we throttled forward, it would slowly surge forward then it would drop rpm's till it knocked a bit and almost stall- then it would rev up again.

Any thoughts?

I tested for vacuum in the fuel tank and I looked briefly at the air-filter intake screen. It was sooty but I didn't see any fine air-filter to check for clogging. (this is a friend's boat that I am not that familiar with). Does an air restriction seem possible? or clogged injectors? Fuel filter was clean.

thanks

 

[lilmandavis]

Re: Merc D-tronic 7.1 L can't get to high rpm

check fuel pressure.

 

[Don S]

Re: Merc D-tronic 7.1 L can't get to high rpm

check fuel pressure.

Don't have a clue what a Merc D-tronic 7.1 L is, do you?

 

[lilmandavis]

Re: Merc D-tronic 7.1 L can't get to high rpm

i think its a ford diesel??!! thats the only 7.1 liter i know of lol
but i would say its not a 7.1

 

[Bondo]

Re: Merc D-tronic 7.1 L can't get to high rpm

The Ford/ Navistar is a 7.3l,...... And Merc. Has used it.....

I believe Merc. is Also using a 1.7l Diesel nowadays.......
And,..... I Believe they call it a D-tronic.........

Anyways,......... IF this IS a Diesel,.........
Change the Fuel Filters,.......
That's the #1 cause of Loss of Power for All Diesels.........