2wdiesel2021 Posted November 13 Share Posted November 13 I have a 2010 Mack CHU613 with an MP8 and we put a new filter head on it and new pump because it idled terrible and wouldn’t rev. New pump abs filter head and exactly the same. Showing zero fuel pressure and will only stay running if we pump the primer the entire time. I am lost here with all these new parts it still won’t make pressure Quote Link to comment https://www.bigmacktrucks.com/topic/74751-2010-mp8-has-no-fuel-pressure-with-new-pump/ Share on other sites More sharing options...
Joey Mack Posted November 14 Share Posted November 14 did you put the little coupler on the pump shaft with a little grease to hold it there during assembly? Quote Link to comment https://www.bigmacktrucks.com/topic/74751-2010-mp8-has-no-fuel-pressure-with-new-pump/#findComment-561915 Share on other sites More sharing options...
2wdiesel2021 Posted November 14 Author Share Posted November 14 Yes sir that’s all there. We even pulled it apart and checked it again. I have two other Mack’s here and i checked all the hose routing with those trucks and it’s the same. I take the fuel pressure sensor out and no fuel comes out even when I get it running. I can get it to rev if one guys primes it and one guy pushes the petal then it just dies off. Quote Link to comment https://www.bigmacktrucks.com/topic/74751-2010-mp8-has-no-fuel-pressure-with-new-pump/#findComment-561918 Share on other sites More sharing options...
Geoff Weeks Posted November 14 Share Posted November 14 (edited) Put a section of clear line on the suction side (temporarily) and see if it is sucking air. You could also just replace the suction hose, might get it. There are specially made "sight glass" that have flare fittings on them you can buy, but clear hose works temporarily. I've chased my tail on suction air leaks before, learned a valuable lesson. M50043 Sight Glass #10 : Apexinds.com come in other sizes as well Edited November 14 by Geoff Weeks 1 Quote Link to comment https://www.bigmacktrucks.com/topic/74751-2010-mp8-has-no-fuel-pressure-with-new-pump/#findComment-561920 Share on other sites More sharing options...
Joey Mack Posted November 14 Share Posted November 14 Is it possible that the fuel regulator got stuck 'open'? Quote Link to comment https://www.bigmacktrucks.com/topic/74751-2010-mp8-has-no-fuel-pressure-with-new-pump/#findComment-561921 Share on other sites More sharing options...
2wdiesel2021 Posted November 14 Author Share Posted November 14 Where is this fuel regulator? I put vice grips on the return side and pumped the primer and got maybe 6psi fuel pressure. It will stay running, sounds terrible but won’t die unless I rev it and hold it until it dies. Just idling it will run all day but rough like it’s lacking fuel. Suction has to be the problem. Quote Link to comment https://www.bigmacktrucks.com/topic/74751-2010-mp8-has-no-fuel-pressure-with-new-pump/#findComment-561973 Share on other sites More sharing options...
Joey Mack Posted November 15 Share Posted November 15 It is hidden on the front of the head where the return line comes out. Quote Link to comment https://www.bigmacktrucks.com/topic/74751-2010-mp8-has-no-fuel-pressure-with-new-pump/#findComment-561996 Share on other sites More sharing options...
2wdiesel2021 Posted November 15 Author Share Posted November 15 Oh yes sir it was fine as best i could tell, I also vice gripped that line off to see if that helped and it didn’t change anything. So it has to be a suction issue somewhere. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/74751-2010-mp8-has-no-fuel-pressure-with-new-pump/#findComment-562010 Share on other sites More sharing options...
Vmac3 Posted November 27 Share Posted November 27 Does it have a a fuel water separator mounted on the frame rail? Quote Link to comment https://www.bigmacktrucks.com/topic/74751-2010-mp8-has-no-fuel-pressure-with-new-pump/#findComment-562771 Share on other sites More sharing options...
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