running very rough

[TBurow]

my truck has recently started to run rough at idle after getting on it, and now seems to do it almost every time i stop even if i drive it easy. it starts to miss and will clear up if i rev it up for a couple of secounds, it used to feel like 1 cyl. but it has gotten worse and feels like 2 or 3, but once i start to accelerate it clears up in a sec or two, rebuilt pump, new injectors, new lift pump, no air leaks. however i think that the ip is starting to leak fuel into the crankcase (i guess i nicked the seal putting it back together) could this be letting in air? would explain the miss after getting on it, blowby getting into the pump.



i think i just answered my question. let me know if this seems right.

thanks

 

[MEby]

my truck has recently started to run rough at idle after getting on it, and now seems to do it almost every time i stop even if i drive it easy. it starts to miss and will clear up if i rev it up for a couple of secounds, it used to feel like 1 cyl. but it has gotten worse and feels like 2 or 3, but once i start to accelerate it clears up in a sec or two, rebuilt pump, new injectors, new lift pump, no air leaks. however i think that the ip is starting to leak fuel into the crankcase (i guess i nicked the seal putting it back together) could this be letting in air? would explain the miss after getting on it, blowby getting into the pump.



i think i just answered my question. let me know if this seems right.

thanks

If I understand what you are saying, it sounds like your pump is acting similar to my pump thats in the shop right now. It would drop rpm enough at idle that it would start to run rough but would clear right up if I tapped the throttle. It has some broken springs in it although I don't know which ones just yet.

 

[rlyons]

my truck has recently started to run rough at idle after getting on it, and now seems to do it almost every time i stop even if i drive it easy. it starts to miss and will clear up if i rev it up for a couple of secounds, it used to feel like 1 cyl. but it has gotten worse and feels like 2 or 3, but once i start to accelerate it clears up in a sec or two, rebuilt pump, new injectors, new lift pump, no air leaks. however i think that the ip is starting to leak fuel into the crankcase (i guess i nicked the seal putting it back together) could this be letting in air? would explain the miss after getting on it, blowby getting into the pump.



i think i just answered my question. let me know if this seems right.

thanks

No a bad seal will leak fuel into the crankcase, not blowby into the pump. If your fuel filter is clean then it sounds like a pump problem.

 

[TBurow]

well its not the ip, i took it out and resealed it and checked all the springs(i replaced all them 2 months ago) it still runs rough at idle, comes and goes when sitting at idle in gear. im thinking it may be the new injectors dripping fuel or not popping at the right pressure. its not a dead cyl, as it runs way rougher when i crack the line loose on an injector. any help would be appreciated. thanks toby

 

[dpuckett]

Do you have a way to test your pump? Things may have LOOKED fine, but could be operating at less than stellar levels. Good idea to check your injectors.



DP

 

[TBurow]

no, not really. i rebuilt the pump a couple of months ago and ran it with the stock injectors for about a month and it ran fine, it started acting up about a week after i put in the new injectors and it comes and goes, sometimes a slight miss at idle and other times a dead miss till i rev it up and then it will idle fine. i pulled the delivery valves off the pump while i had it off and looked for pieces of rubber or metal in them and they were all clean, dumped the fuel out of the ip through a coffee filter to catch any crap that might be in the pump and all was good and clean. im really thinking they did a poor job putting the injectors together and i guess i will pull them and have them tested.

 

[TBurow]

just thought of another thing, i have been getting fuel from a friend from work. he fuels refer units for the railroad. it is in a 200 gallon storage tank in a fuel truck could the fuel be bad?

it looks and smells the same as the fuel i have been using. and it burns the same in my torpedo heater.