CM871 poor power and fuel econ

[Grounded Pilot]

(09-19-2022 )Rawze Wrote:  

(09-17-2022 )Grounded Pilot Wrote:  ...
I re ran the overhead and everything was within tolerances. Re ran the leak test and still getting bubbles. #1 & 2 on the front bank. Haven’t switched to the rear bank again but will in a bit, had to run in town and take care of some things quick. I’m assuming I’ll get bubbles there as well. So back to square one as to why I have 3+ injectors bad in under 9 months?

There are a couple causes of premature injector leakage failures on ISX's.

The most common is air getting into the fuel, eating up injector tip.

The other is some kind of engine abuse. Things like power set to way more power than the tier injector was designed for, or excessive boost (more than about 37-38~ish psi) and pushing the engine hard a lot.

Other than that, it could be injectors that were on a recall list or something?...
ref: http://rawze.com/forums/showthread.php?t...08#pid2508

I could not get the rear bank to bubble except for when turned over by the starter. Hand cranked that dang engine for about 20 min trying! As far as the power, it’s still set how we discussed via email and gets about 35psi boost. However, it was getting 39+psi before we reprogrammed it 6 weeks ago and timed wrong.

I will get the fittings to check the air in fuel problem. The mechanic thought that was a problem a while back and I changed all the fuel lines from the tanks to the lift aux fuel pump inlet. Also pulled the IFSM and changed it due to the mechanic thinking it was possibly cracked internally. Put all new gaskets and o-rings on it then. But didn’t seem to make any difference. Have not rebuilt either the aux or main fuel pimp as it maintains fuel pressure evenly on insight.

I haven’t checked recall status, but I’ll get the serial #’s and check.

I had to hit Kenworth to grab a exhaust stack bracket and caught a tech while I was waiting on parts. His conclusion was that I have injector cup issues due to the carbon “slime” build up around/above the first “step” closest to the tip on the injector. Does this sound like a plausible explanation? Only about 350,000 miles on the head “supposedly”.

If it’s the injector cups, is that a changeable part on an cm871?