Engine/Transmission (1994 - 1998) Engine Miss on Startup

[BSims66173]

Yesterday, I needed to run to the store and get weedeater gas. My truck had not been started that day. We have a new puppy that was around my truck so after starting it I thought I would rev it up a few times to let the puppy know the big monster was alive and about to move. While revving the engine I felt a miss and saw some smoke from the tail pipe. Once on the road the truck ran fine. I have never noticed this before but I have a rather long driveway so I usually just start it and ease down the driveway. Did the same thing this morning when leaving to go to work. Doesn’t do it after truck is warmed up. Also I have been getting around 19 mpg and on last fill up it was down to about 13 or 14. I thought maybe I just wrote my numbers down wrong but now I am not sure. Going to fill up today and see what they are. Could this be the fuel supply and return line problem causing this or maybe timing. The truck is completely stock.

 

[BSims66173]

Checked milage today and it is down to 13. 5mpg. Something is not right. Anyone have any ideas? Thanks

 

[LDPetersen]

My 95' does that sometimes . Seems worse if it sits for a few days. Sometimes it will die and then a restart is needed and all is fine. But most times it does miss a little for maybe 5 seconds. It has done this all spring. Mileage seems normal. I thought it might be in need of a new fuel filter. Has been about 20k miles since the last one. Anybody got any ideas? Thanks Larry.

 

[RBratby]

mine also does this. mine does this only when it is colder outside. what is the temps around where you are at. it probally has to do with the temps.

 

[Lsfarm]

First start

When your engine is first started the cylinder walls and cylinder head are cold. The diesel engine needs to compress the combustion air heating it to ignition temperatures. Our grid heaters heat the incoming air to help a cold engine heat the air enough to support ignition of the injected fuel.

You are getting a miss because the cylinder wall and head are still cold and there is not enough heat to ignite the extra fuel being injected when you try to rev the engine.



You said you normally leave the parking spot and drive slowly down the drive. This is giving enough time for the engine to warm up enough to support complete combustion at higher rpm's. During cold weather this would be much more noticeable even with the grid heaters running, the grid can only heat enough air to support idle speeds, any higher and the engine will miss and blow white smoke [unburnt fuel]. after a minute of idling it will run fine above idle speeds



Bumping the timing to 16 or so helps to reduce the miss and white smoke. But just letting the engine run at low power and rpm for a few minutes is the best, so the cylinder gets warm.



As for the drop in fuel mileage, run several tanks to be sure, you could have only partially filled on the last fillup, or you neighbor with the diesel truck and farm tractor came by and 'borrowed' some fuel.



Hope this helps. Greg L The Noise Nazi