steeler Posted November 3, 2018 Share Posted November 3, 2018 (edited) Hey guys I've got a 2015 lei that is throwing a p20de00 after treatment fuel pressure sensor circuit range/performance fault. I've run through the diagnostics with tech tool with exception of the final test because I don't have the special tool to do it, but everything checks good. The afp runs about the same as engine pressure when the shutoff valve activates, then runs about 45 lbs deactivated. Engine fuel pressure is steady at about 58-60. Any ideas? Forgot to add that I replaced the doser module. Edited November 3, 2018 by steeler Quote Link to comment https://www.bigmacktrucks.com/topic/54735-after-treatment-fuel-pressure-problem/ Share on other sites More sharing options...
turckster Posted November 6, 2018 Share Posted November 6, 2018 Aftertreatment fuel psi should be what.... 90ish psi? What test is it that you can not perform that requires a special tool? Quote Link to comment https://www.bigmacktrucks.com/topic/54735-after-treatment-fuel-pressure-problem/#findComment-408984 Share on other sites More sharing options...
steeler Posted November 6, 2018 Author Share Posted November 6, 2018 13 hours ago, turckster said: Aftertreatment fuel psi should be what.... 90ish psi? What test is it that you can not perform that requires a special tool? I was wrong on that test, all it was was checking the fuel pressure to the shutoff valve, which is the same as the engine pressure. That was the last test, so it just told me "no fault found". I hooked up another truck of the same year just to compare pressures. That one had an after treatment fuel pressure of 90 psi when the shutoff valve opens, then dropped to zero with the valve closed. Mine stays at about 45 with the valve closed. I'm going to run regulated shop air to the shutoff valve at 32 psi just to see if anything changes. Quote Link to comment https://www.bigmacktrucks.com/topic/54735-after-treatment-fuel-pressure-problem/#findComment-409023 Share on other sites More sharing options...
steeler Posted November 6, 2018 Author Share Posted November 6, 2018 Ok hooked shop air to the shutoff valve, that didn't change anything. So if my test vehicle has after treatment fuel pressure of 90, with engine fuel pressure at 60, what "ups" that pressure? I thought after treatment fuel pressure would be equal to engine fuel pressure? Quote Link to comment https://www.bigmacktrucks.com/topic/54735-after-treatment-fuel-pressure-problem/#findComment-409036 Share on other sites More sharing options...
turckster Posted November 7, 2018 Share Posted November 7, 2018 There is a fuel pump mounted behind the module, small little electric pump. When activated it boosts engine fuel psi to 90ish to help atomize fuel at the nozzel. 2007 emission non-catylized engines have the same pump but they are mounted inside the right frame rail mid-chassis. Quote Link to comment https://www.bigmacktrucks.com/topic/54735-after-treatment-fuel-pressure-problem/#findComment-409064 Share on other sites More sharing options...
steeler Posted November 8, 2018 Author Share Posted November 8, 2018 Mine does not have the separate pump for after treatment, but I found the problem. The 7th injector was plugged up. Mack needs to fix some issues with the guided diagnostics in tech tool, it never mentioned anything about that as a possibility for the code I had. Oh well all good now. Thanks. Quote Link to comment https://www.bigmacktrucks.com/topic/54735-after-treatment-fuel-pressure-problem/#findComment-409099 Share on other sites More sharing options...
yeredsh Posted June 18, 2020 Share Posted June 18, 2020 On 11/8/2018 at 8:56 AM, steeler said: Mine does not have the separate pump for after treatment, but I found the problem. The 7th injector was plugged up. Mack needs to fix some issues with the guided diagnostics in tech tool, it never mentioned anything about that as a possibility for the code I had. Oh well all good now. Thanks. my man! that works! Quote Link to comment https://www.bigmacktrucks.com/topic/54735-after-treatment-fuel-pressure-problem/#findComment-453654 Share on other sites More sharing options...
fjh Posted June 19, 2020 Share Posted June 19, 2020 We go to the injector first for most issues as it is the most common problem!Garden path diagnostics can really lead you to a lot of dead ends at times . The CBR setup is a better diagnostic tool if you can get to it! its a more realistic tried and true real world repair path! Believe it or not servicing the air drier more often can benefit in a lot of cases in wet climates WE have noticed the HC Doser gets ruined by water in the air sends shit down the line clogging the injector as well also the the dollar store fuel line gets rotten and can cause repeat issues in the newer units! Quote Link to comment https://www.bigmacktrucks.com/topic/54735-after-treatment-fuel-pressure-problem/#findComment-453705 Share on other sites More sharing options...
steeler Posted July 6, 2020 Author Share Posted July 6, 2020 On 6/19/2020 at 8:45 AM, fjh said: We go to the injector first for most issues as it is the most common problem!Garden path diagnostics can really lead you to a lot of dead ends at times . The CBR setup is a better diagnostic tool if you can get to it! its a more realistic tried and true real world repair path! Believe it or not servicing the air drier more often can benefit in a lot of cases in wet climates WE have noticed the HC Doser gets ruined by water in the air sends shit down the line clogging the injector as well also the the dollar store fuel line gets rotten and can cause repeat issues in the newer units! What is CBR? Quote Link to comment https://www.bigmacktrucks.com/topic/54735-after-treatment-fuel-pressure-problem/#findComment-455093 Share on other sites More sharing options...
fjh Posted July 6, 2020 Share Posted July 6, 2020 If you have a mack logon at your location you can log on and go to this section ! Case based reasoning ! They have collected all of the field repairs and fixes and compiled them for guys to shoot for when having issues with this and other stuff Its one of the few things that they did right with the program ! as its not all theory Its fact base repairs Done by real people not dreamed up by someone whom has never turned a wrench! Quote Link to comment https://www.bigmacktrucks.com/topic/54735-after-treatment-fuel-pressure-problem/#findComment-455128 Share on other sites More sharing options...
steeler Posted July 8, 2020 Author Share Posted July 8, 2020 On 7/6/2020 at 9:36 AM, fjh said: If you have a mack logon at your location you can log on and go to this section ! Case based reasoning ! They have collected all of the field repairs and fixes and compiled them for guys to shoot for when having issues with this and other stuff Its one of the few things that they did right with the program ! as its not all theory Its fact base repairs Done by real people not dreamed up by someone whom has never turned a wrench! Oh yeah, I'm brain dead from the heat lol. What login does it take? Obviously not tech tool login. Something we don't have I'm sure. Impact? Quote Link to comment https://www.bigmacktrucks.com/topic/54735-after-treatment-fuel-pressure-problem/#findComment-455308 Share on other sites More sharing options...
fjh Posted July 9, 2020 Share Posted July 9, 2020 We access thru our dealer portal you may not have access to that on your set up not sure Quote Link to comment https://www.bigmacktrucks.com/topic/54735-after-treatment-fuel-pressure-problem/#findComment-455420 Share on other sites More sharing options...
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