LLY: Surging at idle

[countrycorey]

I've searched this and I'm leaning towards the FPR being bad, but I'd like the input from some of you guys who work on these trucks regularly.

So dad's 04.5LLY has been surging at idle. I replaced the fuel filter after it started and that helped, some but it came back shortly thereafter. He had it worked on at a dealership and they said it was the FPR o-ring and that they cleaned the FPR. This was done back in June or July and it worked, until now. The surging at idle (really noticeable at idle in gear) has returned, am I right in thinking it's the FPR?

Thanks in advance

 

[dmax711]

f.p.r had same prob on my truck.

 

[Big Block 88]

What are your balance rates?? Could be injector harness going out.

 

[Mpsoldier]

fpr if you have efi watch the actual vs demand rail pressure you will see the actual pass the demand and that's what causes the surge

 

[countrycorey]

Can't get balance rates as my v2 is stuck on LBZ PIDs due to a dead laptop and no way to get it to LLY PIDs.

Got it thanks, I'll see what I can find out.

 

[WI Huck]

FPR but look into a whole pump instead if you are at 150K or better on mileage.