Goddy454

A little update, I was able to clear the EGR fault for a little while and with that erased the truck will do a regen. The regen failure is a definte result of the EGR fault. Let me also add that the EGR valve I put in was an aftermarket as the Mack valve is like 3K. I know a lot of this aftermarket stuff is crap, should I just get a Mack unit?

Happy Holidays All. I have a baffling issue here. The truck is throwing a 2791 FMI 5, current below normal or open circuit. I have replaced the valve and the harness is a couple months old, fault was present before changing these items. The truck is calling for a regen also but will not initiate one through the dash switch or through PTT either. I have done the PTT test of checking resistance to the valve directly and passed with 4.1 ohms. Did the second test of connecting valve and checking resistance from ECM connector pin to pin. Checked out with 4.1 ohms too. With these results PTT says fault cant be recreated. As of now that would make me believe ECM but PTT makes no mention of that even being a possibility. Oddly enough when truck is cold and waiting to reach normal temps it started to idle up and do its own regen. I stopped it and then pressed the dash switch and it proceeded to perform a regen. I once again stopped it as the truck was in the garage. Once the truck reached operating temps I attempted to run a regen and couldnt. The switch would not permit me nor would PTT even though all conditions said OK. I attempted the EGR valve test and I could not do that either. The window showing commanded position would flicker a red X and read 95. Anybody give me their take on this. That would be appreciated. Thanks

I certainly will I know these are problematic. Thanks

I ran a crystal sublimation and this seems to have corrected the issue with the rising number during a regen, it also set the soot back down to zero when it finished, but the truck is now calling for a regen everyday, i will have to a snap test and check into things further. Thanks

I have a question about Premium Tech Tool. What is EATS maximum registered current poisonong level ? I am under the assumption that it is the soot level, am I correct? I always see this level drop during a regen but on this particular truck it actually increases. What would be a possible cause of this? The truck is a 2014 GU813 with an MP7. Thanks for any help.

I ended up replacing the fuel filter head assembly along with all the sealing washers and all is well. Thanks

Thank You

Thats the bulletin I've been using all along on this diagnosis. Thanks

Where its coming out into the tank looks ok, really nothing. Was trying to get a pic but couldn't get a good one.

Here is a pic of the leak I am referring to, in the pic its on the left. Thanks

Good Morning, I have a MP8 with a hard start after sitting, cranks long but will eventually start, this has been going on for some time. Truck runs fine once running but after sitting overnight or for a few hours its tough to start. I have run the test with the clear tubing from the front of the head to the tank with the return port in the fuel filter housing plugged off. The test instructions say to look for heavy foam or large bubbles. I do not see any large bubbles but do see foam. I have never run this test on another truck so I cant determine if this foam is considered typical or abnormal. I would appreciated any comments from anybody on their thoughts. Also according to the instructions they say that the primer pump is not a source of air in the fuel system. I did notice that the fitting to the right of the primer pump knob is leaking when I pump the handle, any thoughts on that. Thanks for any help.

Our trucks here look for that, it was just an intermittent fault where I didn't notice the light was going off on the dash, I only caught it when the speed came down and I was not able to start it back up, that's when it showed itself. I have had this problem on others, but it was completely dead and threw a code. Thanks for your help.

Replaced the switch and so far no probs. Thanks

Also the switch is not throwing any codes like I have had with others which is also leading me to an air issue.

OK here is what I found, while looking more the speed cut out then would not ramp up at all. That's when I noticed the park brake lamp was not illuminated. I am going to replace the switch first but I think I might have an issue with the park brake valve or an air issue in that circuit. Something just doesn't sound normal when I apply and release the spring brakes. Figured I would give you an update and thanks. Will let you know what it was for sure when I find out.