customer came in today told me the dealership said he needed two injectors. soo i hooked up the scanner and came up with NO codes? it runs like a dog and sounds like its missing. so i ran and injector buzz test...came up fine. ran an injector disable test and number 5 had no change so im thinking its the culprit. I ran a cylinder contribution test just to be sure and cylinders 5, 6, and 7 were reading negative numbers.(which is bad according to the scanner). so do i replace the 3 injectors? or is there something else i should be looking for?

 

that would be what i would do yes

 

You should load test the batteries and then test the FICM before going through the trouble of replacing injectors.

How many miles on this truck? More info would help...

 

179k batteries load tested fine, doesnt blow any smoke like its a bad injector but it had a p0205 code cylinder 5 contribution/balance fault.

 

TEST THE FICM!!!

 

Again, test the FICM and then get back to us. It's possible it needs an injector, but the FICM is a 10 minute test.

 

tested the ficm its fine. so i replaced the 3 injectors it started up and ran perfect yesterday and on the test drive. today went on another test drive and it died while driving. hooked up the scanner and it says injector curcuit low on all 8 injectors. the injector plug in on the ficm was zip-tied on when i took it apart. so re zip tied in and it was fine till the 2nd test drive.


also i was reading about which ficm the truck should have the truck is a 12/02 model year and it has a 4 screw ficm. shouldnt it have a 7 screw?

 

it was proly replaced previously

 

It came with a 7 screw, it was obviously replaced at some point. Shouldn't matter. Is the FICM plug itself broke or the harness that goes to it. I would just get a new harness if it's broke, they're EXTREMELY finicky when it comes to those plugs, they will run like complete crap with it just slightly loose.

You think those 3 original injectors even needed replacing? Just curious.

 

yes they did need replacing they were not contributing but it passed a buzz test so they were firing but not correctly. so just for 6.0 owners reference NEVER buy cheap fuel filters! i got master pro filters for this job and turns out that was causing my no start issue! the top filter pushes down on a check valve of some sort and the cheap filters dont push it down all the way, not letting fuel into the bowl and causing a injector circuit low on even injector due to no fuel. replaced them with a napa filter set and it fired right up!