2013 ISX15 Cummins fuel trouble!

I bought this truck with a fresh overhaul on it maybe 3 years ago. It had 20k on the overhaul. It’s a 2013 Pete 389 with isx15 in it engine serial #79556660 and family #CCEXH0912XAQ. This truck was modified prior to me buying it and has a fully “custom” exhaust as well as a “custom” EGR. this truck no longer has the factory exhaust manifold either and has a non VGT turbo on it. Tuned to 600 hp 2200 torque. The ecm has “custom” programming too because of the “modified engine”. So, it ran great until last year. The cam worked loose on cylinder 3 and destroyed the cam. I had a new cam and new rockers put in it in December. It ran good but throaty. Fast forward about a month later it began throwing fuel codes and was kind of feeling fluttery at 1500 rpm and when accelerating there was times it would spat or stumble at you a little like it was clearing its throat. Took it back where the cam got done. They found fuel rail pressure codes and threw a new pressure sensor, and some sort of blow off valve deal on the front of the fuel rail. They also found oil in my injector harness and pulled it for a new one. So, wasn’t fixed. They checked for air being sucked in. Nothing found. They noticed my main gear driven high pressure pump was walking pressure 300-500 psi so they replaced that entire unit. Said it was good, it wasn’t. It was throwing codes for things it no longer had. Took it to Peterbilt, they spent all day with it. Said one of my supply lines was collapsed. Supposedly. So they put all brand new supply lines on it from the PACCAR water separator to the tanks. Didn’t fix it. They put injectors in cylinder 5 and 6. Said they didn’t like how those tested. Didn’t fix it. New o rings on the rest of them. Didn’t fix it. Then they blamed my tuning. So I tried a new ecm with a fresh tune. Didn’t fix it. So I put the old Ecm back on. Went and had it retuned to fix the codes for non existent exhaust parts. Ran better, still have the original issue though. Went back to Pete earlier this week. They said it now has codes for the actuator on the pump. I thought this was weird cuz that was new with the new pump. They replaced it. Claimed it fixed my codes. However they noticed my fuel bowl in the upside down paccar frame mounted filter wasn’t filling up. That filter pulls from the top. I took it home because Peterbilt gave up. I tore down that housing and checked the center spring loaded valve, seems to actuate when you push it with a finger. So I blew out the valve and the fittings and reinstalled with new o rings. Put a new filter in it too and it seemed to fill up. Still have the problem though. I ran it for a day then took my laser thermometer gun and took temperature readings of all the lower manifold bolts. They were as follows
#1. 197 degrees
#2. 560 degrees
#3. 230 degrees
#4. 230 degrees
#5. 208 degrees
#6. 196 degrees

I figured 1 and 6 should be the coldest as they are furthest from the turbo but what really bugged me was cylinder 2. So I immediately bought a new injector for that cylinder and installed it. HAS NOT FIXED THE STUMBLE. This is starting to seriously P*$$ me off hardcore at this point. The overhead has been checked twice. Injector cut outs have been done. Supposedly they passed. By Peterbilt. Peterbilt also checked my engine harness ohms. Said it passed. WHAT AM I MISSING??! does this turd need 3 more injectors or is it something else with the delivery?? The only stuff not replaced is the return lines, the priming pump, and whatever that fuel block is on the side of the engine that all the lines go to with the filter and all. Filters have been done many times. It smokes white whenever it does the flutter for a prolonged time and it smells rich some times. At first start up it runs for a quick second just fine then after a minute or two you hear it start doing chug chug chug chug chug crap til it gets above 150 degrees. Then it’ll idle smoother but that problem is still 100% there especially when you are driving. No coded as of right now. So I don’t know where to look. I’m probably over 25k deep in this ###-apart and I’m just at the end of the rope here. The priming pump is engaging, I hear it buzzing. I do not know what pressure it might have. I also don’t have a sight glass kit right now to test and see if that paccar housing is no good. I can surely buy tools though. Anybody… please help if you can this is causing unreal stress.

 

Not really. A little but no. Nothing like it was. Here are the new readings

186
290
230
228
195
186

these readings are taken using a laser thermometer gun on the lower manifold bolts. 2-4 bolts sit behind the turbo. I will note that my fuel bowl is now sitting way too low again.

 

I guess I haven’t checked the tank for bubbles. I did notice small bubbles in between the fins of the filter whenever the bowl actually has more fuel in it.

 

Peterbilt did the sight glass tests on the supply lines. I don’t have a sight glass kit.

 

I looked into the tanks with a flash light to watch for bubbles and didn’t see anything. Can’t see the pick up tubes very well. I bypassed the fuel filter housing and nothing changed. So I guess next up I will put the supply line in a bucket and see what the engine does then.

 

i don’t have a way to run both supply and return lines to the bucket at this time because the return goes all the way to the T. Unless I use separate buckets. After running the supply line from the lift pump to the bucket it still acted up. So I’m guessing it’s not the fuel housing or the supply lines.