rough idle, runs bad

[blowinsmoke]

a friend called me last week. his 03 started running bad, then wouldn't run at all. I went to look at it, smarty had codes for low and high fuel psi. my other scantool had same codes but said rail voltage high and low. I checked fuel psi @ cp3=3psi at idle. started it, idled rough, brought it up to 1700 rpm and the quad rail pressure gauge spiket to 30,000 and died. checked codes again -rail psi voltage high. told him it was probably rail psi sensor. he replaced it, and still has same symptoms. the truck had a smarty, quad std, and tst on it before it cratered, everything was taken off before testing it(put quad back on to monitor rail psi)

 

[rbattelle]

Maybe a failed rail pressure relief valve?

Ryan

 

[steved]

I was thinking a faulty FCA surging??



The rail relief only "pops" if the rail pressure exceeds specs... it doesn't regulate the rail pressure...

 

[rbattelle]

The rail relief only "pops" if the rail pressure exceeds specs... it doesn't regulate the rail pressure...

True, but remember there were issues with the valves getting weak over time from running pressure boxes.



Ryan

 

[steved]

True, but remember there were issues with the valves getting weak over time from running pressure boxes.



Ryan

But if it spiked to 30k psi, shouldn't that indicated the relief valve is holding???

 

[snoman102]

what are the fc's?

 

[steved]

what are the fc's?

I assume you meant FCA???



FCA = Fuel Control Actuator... lots of threads on the subject.

 

[blowinsmoke]

I was also leanin toward the fca but the lack of codes kept me from saying so since i was wrong once. I know that there isn't enough fuel; press but i've never seen one run like this on a bad lp

 

[AllianceDiesel]

sounds like the fca is bad, it isn't controlling the fuel pressure correctly.

 

[snoman102]

I assume you meant FCA???



FCA = Fuel Control Actuator... lots of threads on the subject.

No i ment Fault Codes. they come in handy to look up troubleshooting trees. or he can just keep throwing parts at it.

 

[blowinsmoke]

I had them written down somewhere... will see if i can find them tonight

 

[steved]

No i ment Fault Codes. they come in handy to look up troubleshooting trees. or he can just keep throwing parts at it.

Just do a web search... that's all I ever do. They are only generic codes, we don't see the manufacture specific codes.

 

[VolCTD]

As dumb as it may sound have you checked the fuel filter & the air filter? I had the same problem and finally took it back to the dealer and told them I didn't want to see it again until they figured out the problem. They called a couple hours later and said it was a dirty air filter (I say "yeah right!") but it fixed it. A couple days later the fuel filter clogged and I had to change it too. Now both of these where Fleetguard and had less than 5000 miles on them. Who knows??? It's worth a look and it's a cheap fix if it is that. I was heading for the FCA next if none of that had fixed it.

 

[AllianceDiesel]

if you get me the codes I can get you the diagnostics chart

 

[blowinsmoke]

got it fixed. was another bad rail sensor. exchanged it and the next one worked. thanks for the help. do yall know if the manuals in genos garage have the diagnostic charts?

 

[AllianceDiesel]

ya but it depends on what year you get, i think 06 and newer does, i get mine strait from chrylser webstie