ROUGH IDLE AFTER WARMING UP

[ringer]

Hi all,

New to the forum and new to diesels as well.

I have a new to me 1985 3/4 ton Chevy Suburban 6.2L diesel 4x4 with a three-speed tranny and NP 208 transfer case. 119,000 miles.

The truck runs great at first(fires up easily) but as the day wears on, the idle gets rough, so rough I get a bit of shaking in the truck. There is no smoke that I can see either at idle or at speed/acceleration. I also seem to be losing power as the day goes on.

I have changed the fuel filter. Is it an injector?? I just need some idea on where to start. Thanks in advance!

Mike

 

[Pookster]

Im still learning about these diesels myself.

my uneducated guess says that perhaps your not getting fuel delivery anymore-

How does it run on the highway?

 

[doctor4x4]

here are my thought's
either the lift pump ( my 1st bet )
or the injector pump
as the engine gets hotter the rubber seals are letting air in or not pumping properly
I recomend ya put a in line LOW PRESSURE electric pump in and see if that fixs it ( cheep and easy ) and even f it dont its a great feature to have I.M.O.
BEST OF LUCK
&
WELCOME !!!!!
R

 

[ringer]

TY for the responses guys!

The truck runs ok on the highway, but seems short on power. However, as mentioned, this is my first diesel and I am not sure of how it should feel.

I do know, it is "missing". In park with a litte fuel, there is a pronounced shudder to the engine that smooths out a bit at higher rpms.