John3406 Posted January 21, 2022 Share Posted January 21, 2022 My e6 350 in my 88 superliner is starting to defuel around 1550 rpms. Im thinking it shoul pull good to 18 or 1900. It runs damn good till you hit 1550 and by 1600 it has nothing. When do your guys e6 start refueling. Im going to send the pump out im sure governor is weak. Thanks Quote Link to comment https://www.bigmacktrucks.com/topic/69092-e6-350/ Share on other sites More sharing options...
theakerstwo Posted January 21, 2022 Share Posted January 21, 2022 Start with checking the fuel presssure under load and see if its loosing pressure under load. Quote glenn akers Link to comment https://www.bigmacktrucks.com/topic/69092-e6-350/#findComment-487576 Share on other sites More sharing options...
mrsmackpaul Posted January 21, 2022 Share Posted January 21, 2022 First things first When you are loosing pull are you still making smoke ? If your making smoke when the power drops off fuel isnt your issue Should pull like a train at least till 1900 or 1950 Paul Quote Link to comment https://www.bigmacktrucks.com/topic/69092-e6-350/#findComment-487581 Share on other sites More sharing options...
John3406 Posted January 21, 2022 Author Share Posted January 21, 2022 Fuel pressure is fine. No smoke. The pump is defueling like its governed at 1600. Empty or loaded makes no difference. Free revs to 2000. Just will not pull at all past 1600. On a hard pull its at 38 psi manifold pressure till you hit 1550 rpm then it starts dropping by 1650 its lucky to have 10 psi Quote Link to comment https://www.bigmacktrucks.com/topic/69092-e6-350/#findComment-487583 Share on other sites More sharing options...
JoeH Posted January 22, 2022 Share Posted January 22, 2022 (edited) Change your fuel filters. Primary and secondary. Edited January 22, 2022 by JoeH Quote Link to comment https://www.bigmacktrucks.com/topic/69092-e6-350/#findComment-487642 Share on other sites More sharing options...
JoeH Posted January 22, 2022 Share Posted January 22, 2022 Clogged fuel filter symptoms are exactly that. Your truck acts like the governor is kicking in at a lower RPM than you remember. Quote Link to comment https://www.bigmacktrucks.com/topic/69092-e6-350/#findComment-487643 Share on other sites More sharing options...
Popular Post fjh Posted January 22, 2022 Popular Post Share Posted January 22, 2022 22 hours ago, John3406 said: My e6 350 in my 88 superliner is starting to defuel around 1550 rpms. Im thinking it shoul pull good to 18 or 1900. It runs damn good till you hit 1550 and by 1600 it has nothing. When do your guys e6 start refueling. Im going to send the pump out im sure governor is weak. Thanks Don't pull the pump till you check the easy and cheap, stuff puff limiter, make sure the tank vents arn't clogged ,,change them fuel filters as mentioned is it rob bosch or AMBAC? 3 Quote Link to comment https://www.bigmacktrucks.com/topic/69092-e6-350/#findComment-487646 Share on other sites More sharing options...
theakerstwo Posted January 22, 2022 Share Posted January 22, 2022 If it holding 38 psi boost at 1500 then fuel pressure is ok and it got more than enough boost.Has this engine ever pulled up to 2100 before and just started this?A maxidyne engine will start to defuel early in the rpm range.What trans has this truck have? 1 Quote glenn akers Link to comment https://www.bigmacktrucks.com/topic/69092-e6-350/#findComment-487671 Share on other sites More sharing options...
John3406 Posted January 22, 2022 Author Share Posted January 22, 2022 7 hours ago, theakerstwo said: If it holding 38 psi boost at 1500 then fuel pressure is ok and it got more than enough boost.Has this engine ever pulled up to 2100 before and just started this?A maxidyne engine will start to defuel early in the rpm range.What trans has this truck have? Its got a 12 speed. When i first got it a couple years ago it pulled good to 1800 and its slowly gotten worse. 1800 was fine but 1600 isnt because when you shift its down to 1200. Quote Link to comment https://www.bigmacktrucks.com/topic/69092-e6-350/#findComment-487697 Share on other sites More sharing options...
Joey Mack Posted January 23, 2022 Share Posted January 23, 2022 ok... just because.... is the throttle lever loose or slipped out of adjustment? jojo Quote Link to comment https://www.bigmacktrucks.com/topic/69092-e6-350/#findComment-487704 Share on other sites More sharing options...
theakerstwo Posted January 23, 2022 Share Posted January 23, 2022 This should have Robert bosch pump on it.Does it have the AFC control on top of the governor or the air valve in the front of the pump? 1 Quote glenn akers Link to comment https://www.bigmacktrucks.com/topic/69092-e6-350/#findComment-487705 Share on other sites More sharing options...
JoeH Posted January 23, 2022 Share Posted January 23, 2022 Sometimes filters clog slowly... And they do just that. Slowly over time they "trim" your governed speed lower and lower as the filter acts as a restriction point. If you haven't changed them recently then it's definitely worth doing before you go jumping on a $3,000 pump rebuild. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/69092-e6-350/#findComment-487706 Share on other sites More sharing options...
Popular Post theakerstwo Posted January 23, 2022 Popular Post Share Posted January 23, 2022 But he is saying it builds 35 psi boost.This makes me think its got the fuel turned to it alot. 2 1 Quote glenn akers Link to comment https://www.bigmacktrucks.com/topic/69092-e6-350/#findComment-487708 Share on other sites More sharing options...
Joey Mack Posted January 23, 2022 Share Posted January 23, 2022 JoeH and Glenn... are you guys talking about the reversing relay screwed into the the intake manifold? I am working on a Superliner with an E-6 4valve, and I was wondering if I should replace the reversing relay.. I havent checked to see if I can get one yet... just curious, Jojo Quote Link to comment https://www.bigmacktrucks.com/topic/69092-e6-350/#findComment-487709 Share on other sites More sharing options...
JoeH Posted January 23, 2022 Share Posted January 23, 2022 I've never seen a Mack that makes 38 psi boost. My older endt676's peak at about 27, and my e7-350 is the same. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/69092-e6-350/#findComment-487711 Share on other sites More sharing options...
JoeH Posted January 23, 2022 Share Posted January 23, 2022 3 minutes ago, Joey Mack said: JoeH and Glenn... are you guys talking about the reversing relay screwed into the the intake manifold? I am working on a Superliner with an E-6 4valve, and I was wondering if I should replace the reversing relay.. I havent checked to see if I can get one yet... just curious, Jojo We deleted the one on our '79 endt676 because the fitting on the intake manifold broke. Barely makes any smoke, but this truck has always spooled up fast and ran like a beast. Quote Link to comment https://www.bigmacktrucks.com/topic/69092-e6-350/#findComment-487712 Share on other sites More sharing options...
theakerstwo Posted January 23, 2022 Share Posted January 23, 2022 A 88 should have the AFC made on top of the governor housing if its a robbert bosch.A 82 or older may have the Amco pump with the limit cylinder on the front of the rack with the reversing relay in the manifold.If its got a reversing relay then to check to see if its messed up just disconnet the line to the cylinder on the front of the pump and it will not limit the rack at all. 2 Quote glenn akers Link to comment https://www.bigmacktrucks.com/topic/69092-e6-350/#findComment-487713 Share on other sites More sharing options...
Joey Mack Posted January 23, 2022 Share Posted January 23, 2022 I was curious about the boost pressure that was posted.. I didnt think they made much more than 32 psi, but my knowledge is more about E-7 and E-Tech... Jojo 1 Quote Link to comment https://www.bigmacktrucks.com/topic/69092-e6-350/#findComment-487714 Share on other sites More sharing options...
Joey Mack Posted January 23, 2022 Share Posted January 23, 2022 The RW I'm working on has an Ambach pump with the reversing relay and a Bimber valve.. I guess i'm robbing this thread for some knowledge, thanks again.. jojo Quote Link to comment https://www.bigmacktrucks.com/topic/69092-e6-350/#findComment-487715 Share on other sites More sharing options...
Onyx610 Posted January 23, 2022 Share Posted January 23, 2022 That’s the best part of this site. Nobody knows everything…idk if this is your style pump, but I posted this a little while ago. It has some good info in it and it might help point you in the right direction. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/69092-e6-350/#findComment-487716 Share on other sites More sharing options...
Joey Mack Posted January 23, 2022 Share Posted January 23, 2022 Robert Bosch 8100... I beleive... I really wish that I worked in the pump room 20+ years ago, it is my only regret, during my Mack years... jojo Quote Link to comment https://www.bigmacktrucks.com/topic/69092-e6-350/#findComment-487717 Share on other sites More sharing options...
Popular Post theakerstwo Posted January 23, 2022 Popular Post Share Posted January 23, 2022 8 minutes ago, Joey Mack said: 4 minutes ago, Joey Mack said: Robert Bosch 8100... I beleive... I really wish that I worked in the pump room 20+ years ago, it is my only regret, during my Mack years... jojo The first year i worked for mack here i did clutchs and springs more than any thing and second year i got off of that and got in engine and trans with other things and did alot of injector repairs so was not much chance of me getting in the fuel room as dirty as i was. 2 1 Quote glenn akers Link to comment https://www.bigmacktrucks.com/topic/69092-e6-350/#findComment-487718 Share on other sites More sharing options...
theakerstwo Posted January 23, 2022 Share Posted January 23, 2022 When i went to freightliner a few years latter i did work in fuel room but the was cummins pump and injectors. Quote glenn akers Link to comment https://www.bigmacktrucks.com/topic/69092-e6-350/#findComment-487719 Share on other sites More sharing options...
Onyx610 Posted January 23, 2022 Share Posted January 23, 2022 Pretty cool that dealerships had a pump room back then. Now it seems they just send it out. I think a lot of spring work is sent out too or customer is referred to a place. Quote Link to comment https://www.bigmacktrucks.com/topic/69092-e6-350/#findComment-487720 Share on other sites More sharing options...
Joey Mack Posted January 23, 2022 Share Posted January 23, 2022 there is a bunch of things that are sent out or just bought as a reman now.. jojo 1 Quote Link to comment https://www.bigmacktrucks.com/topic/69092-e6-350/#findComment-487721 Share on other sites More sharing options...
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