Intermittent rough running, coughs when starting

[sandyc]

glow plugs?

 

[Rocky Hoffler]

A diesel eng needs certain things to run it was running before so we assume that it's in time. So you have to have fuel and air, compression makes it fire have you checked air filters to see if they are clean . secondary air if equipped will sometimes look clean but can be stopped up take filters out and if it still does not start get a can of silicon spray as this is less likely to damage eng as starting fluid spray in intake while cranking. If it trys to run or starts leads toward fuel delivery problem. Good Luck

 

[rbargeron]

"Coughs when starting"

• 
  When cold starting, engine runs rough and sputters for a few seconds, kind of like a gas engine that has too much fuel. Requires glow plug even in hot weather. Sometimes takes several starting attempts. After a few seconds it runs smooth. Warm starts are fine.............................../QUOTE]
  
  Does this mean when it sputters it is blowing back? Can you describe the coughing and sputtering a little more? Any mechanical "ticking" with it? Maybe a lazy intake valve?

 

[BeezFun]

glow plugs?

Forgot to mention, that was first thing I checked.

 

[BeezFun]

...have you checked air filters to see if they are clean . secondary air if equipped will sometimes look clean but can be stopped up take filters out and if it still does not start get a can of silicon spray as this is less likely to damage eng as starting fluid spray in intake while cranking. If it trys to run or starts leads toward fuel delivery problem. Good Luck

I put in a new air filter because the old one was a bit dirty, but didn't think to leave it out. There's no secondary filter on this engine. Never heard of spraying silicon spray, I guess a diesel can burn just about anything.

 

[BeezFun]

Does this mean when it sputters it is blowing back? Can you describe the coughing and sputtering a little more? Any mechanical "ticking" with it? Maybe a lazy intake valve?

I would not say it's blowing back. It reminds me of the old days when cars had manual chokes. If you choked it too much it would flood and when it finally started it kind of sputtered to burn the excess fuel in the cylinder. It does belch a good bit of black smoke when it starts, but not much different than most diesels and particularly one this old (made in '95) that doesn't have all the new air pollution crap on it. It doesn't smoke at all once it's running.
I don't hear any ticking and I adjusted the valves.

 

[doxford jim]

If you can get at them easily, I would be inclined to remove the fuel injectors for testing. That way you can rule out the injectors if they test good and don't leak at all.
Prior to that I would also run some fuel treatment through the engine with the idea of cleaning the injector tips of carbon. Maybe double the recommended dose and work the engine hard will help.
I once had the engine in my F250 emit grey smoke smelling strongly of diesel fuel when running. I put triple dose of fuel treatment in and ran the engine hard for a couple of hours and it cleared up the problem for me. I have not had any trouble since. I think the truck spent too much time without working the engine properly and allowed a varnish type coating to build up.
Anyhow, treating the fuel won't be expensive and I am sure you will notice an improvement of some sort, but whether it will be enough remains to be seen.

 

[BeezFun]

If you can get at them easily, I would be inclined to remove the fuel injectors for testing.

That's my next step, they're really easy to take out. I found Midwest Fuel Injection, they're all over the country and have a place pretty close to my house. If anyone in the Chicago metro area knows a good place that does injectors, please post.

 

[rbargeron]

My first thought was an obstructed injector - maybe get one new injector and try it in different cylinders to see if it helps. Sometimes doing a pattern test costs more than a new injector and then you have to buy one anyway.

 

[Bird]

My first thought was moisture, or just a little bit of water, in the fuel tank.