Cat 6nz Engine Flutter and electrical problems

Hey everyone I’m hoping to get some help on here. I have a 2006 T800 with a Cat c15 converted to a 6nz 800 marine came and 8501 injectors and a 550 cat tune with a 70 pin ECM. Truck ran great after overhauling it little over a year ago. Then one hot day in South Carolina stopping for fuel I noticed it ran rough. Kinda came and went but started getting worse. I was told a bad injector so changed it out then another and another till I got all 6 replaced. Then replaced. Then suspected combustion gas past the rings so pulled them all back out and reamed out the seats in the head and new injector rings still there. Then suspected air in fuel so replaced all fuel hoses and lift tubes and valves. New check valves pressure regulator both filter housings hand primer fuel transfer pump even new fuel tanks as one was leaking a little. Same problem then installed a fass system and starting the truck I knew my problem was solved. Lasted a little over a day then back to the problem. Then went to wiring and put all new battery’s all ground and hot wires from battery’s to engine and altenator and fixed a few connections that looked green and a new 4 post solinoide in battery box that looked rusted and but electrical grease on any connection I could find. Swapped out ecm tried different tunes problem still there. Ran many overheads and checked back Lash and timing. Then got rid of the 800 cam and went to a normal 6nz and all new 8501 injectors again including new both engine wire harnesses on engine and it runs a lot better but it gets moody here and there and idle is good at 600 but Reving it up to 1000 it’s rough. I’ve done all timing sensors MAP sensor fuel temp sensor has a new turbo since the other one started pushing oil. Checked for air leaks on the boost side. Engine pulls it has a little blowby but good burns no oil or coolant. never overheats and all fluids look like they should. It is straight piped and no blockage on exhaust side. I’m leaning electrical now. I feel like I smell rotten eggs but battery’s test good and they are almost new. Tried touching them after running all day and also wires nothing feels hot. My Jake brakes seem to weaken up here and there then go back to normal but all 3 stages work. Also my ABS light comes on when the trailer is hooked up but only with lights on. Then pushing on the brakes the rear clearance lights want to light up as well. Also my dash lights flicker a little but go back to normal if I mess with the dimmer dial. Speedometer and tack work but odometor quits reading here and there sometimes for a whole day then works again for 2 days. Also fan indicator light work work all the time but when it does it’s backwards it lights up when the fan is off. Anybody got some advice on bypassing some grounds or wires that could give me some answers instead of throwing more money into this thing? This problem is intermittent but more bad then good. Any advice is appreciated

 

Thanks I already did that last week with all new injectors and problem is still there

 

sorry for a late reply I hadn’t been on here for a while but yes I had a glass o in just a few days ago and it’s as clear as can get so I’m ruling out air in fuel. I got rid of the primary filter and installed a fass pump the feeds the transfer pump so from there on everything is pressurized. If I had a cracked fitting should I not see a leak. I’m not sure what fitting your talking about but I do know if I don’t stay on top of changing my filters I get cavitation and you can hear and feel it on the steel line that goes from transfer pump to the secondary filter. I got rid of all 90’s the only one that’s left is the supply side on transfer pump and I replaced the oring on it and it’s fed by the FASS pump it makes around 16 psi. I have a guage on there and any restriction on the fass filter I have a problem right away so I have to change them often

 

I have not done a new cab to ecm handed but had it all apart including the plugs your saying cleaned everything up and used electrical grease on it all. My Abs ended up being on trailer side so that part is rolled out now. My Jakes however seem to pop good then get weaker while braking and also seem not to turn off in time sometimes I get an extra pop after pulling it out of gear. They work on all stages tho. Would a hanging Jake cause this? It’s still intermittent depending on the day and same thing with the Jake switch on off position