Bad FCA?

[Superdawg]

I should have left it alone..... After recent install of Bosch Reman injectors, it runs pretty good. Years ago, I replaced the pressure relief valve and FCA chasing some engine issue.
I thought I would swap those pieces back in to see if it would run any smoother. I unplugged the FCA and attempted to remove it but I had tightened the screws down so tight last time I dinged the head of one up. I snugged it back up and swapped out the pressure relief valve with the one that was in there.
I started it up and it ran rough. I put my the other pressure relief valve back in and it still ran rough.
I then realized I did not plug the FCA in. I plugged it in and it still runs rough. No difference in plugging the FCA in or not plugged in. Very rough.

Bad FCA that just gave up the ghost when i started monkeying with the system?

Did I introduce air into the system changing the pressure relief valve that has to work itself out?

thanks,
Tom

 

[cerberusiam]

No, the rail bleeds itself every time it starts. I hate to say it but reman injectors are a crap shoot.

 

[Superdawg]

Thanks Cerb. . I will check the PRV tomorrow and work on getting a replacement FCA. Probably check w/ TC Diesel or Genos for the part.

 

[Superdawg]

Okay. So I did the Pressure relief valve test (thanks to previous post by Cerb):

The rail PRV can easily be tested to see if it is bad. Remove the banjo from the top and bag the line end, clean the PRV well with a cleaner and blow dry. At operating temp start the truck, unplug the FCA connection for 20-30 seconds. If the PRV well is still dry it is good, if there is any fluid the spring is weak or the seat etched.

I did this and checked both PRVs that I had. Both leaked substantially with bubbly diesel overflowing the top of the PRV. Engine runs very rough.

Order a PRV and then check again to see if the FCA is working?

 

[cerberusiam]

Yep, if it is leaking it can cause a rough idle and other problems.

 

[Superdawg]

Final wrap up: Truck is fixed.
I installed rebuilt pressure relief valve. Tested it, doesn't leak. Truck ran a little better but still rough. Not driveable. No difference in plugging FCA wire in or out.
Replaced FCA. A PIA because I stripped the head on a screw earlier. Done.
Put new FCA in. No difference. Hmmmmm......
Looking at the rail, I noticed the top of the rail pressure sensor was a little tilted. Idled the truck and when I wiggled the top of the rail pressure sensor, the truck engine would cut out.
Ordered a rail pressure sensor. Installed. Runs good. Yaay.
I realized that earlier, instead of using the proper sensor socket to remove the pressure relief valve, I used a wrench. I must have hit the plastic top of the rail pressure sensor and broke it. Use a socket and save yourself some grief.
Thanks to Cerb for the advice. Thanks to Todd at TC Diesel for the parts and good advice.