montanacombineman Posted December 17, 2010 Share Posted December 17, 2010 My '96 Mack E7 427 has no power, did a head job over the summer, it ran good for a few days, and now won't build more than 10lbs of boost, no black smoke anymore. Pressure checked the charge air cooler, replaced foot pedal and no improvement. 1 Quote Link to comment Share on other sites More sharing options...
speedy Posted December 17, 2010 Share Posted December 17, 2010 Sounds like a fuel pump problem. How's the fuel filters? Collapsed fuel line? Quote Link to comment Share on other sites More sharing options...
cxn613 Posted December 18, 2010 Share Posted December 18, 2010 My '96 Mack E7 427 has no power, did a head job over the summer, it ran good for a few days, and now won't build more than 10lbs of boost, no black smoke anymore. Pressure checked the charge air cooler, replaced foot pedal and no improvement.Check plastic gear on fuel supply pump. See already were the truck half runs, but there is an issue with the supply pump. Quote Link to comment Share on other sites More sharing options...
fjh Posted December 18, 2010 Share Posted December 18, 2010 Check plastic gear on fuel supply pump. See already were the truck half runs, but there is an issue with the supply pump. WHAT HE SAID! Quote Link to comment Share on other sites More sharing options...
montanacombineman Posted December 18, 2010 Author Share Posted December 18, 2010 Have already replaced the supply pump, changed filters, etc. now wondering if there might be a short somewhere, if you have any more ideas let me know, i'm about to give up on these mack trucks. Quote Link to comment Share on other sites More sharing options...
fjh Posted December 19, 2010 Share Posted December 19, 2010 Have already replaced the supply pump, changed filters, etc. now wondering if there might be a short somewhere, if you have any more ideas let me know, i'm about to give up on these mack trucks.what trans do you have? If it Is a Mack trans check to see the torque limit is un pluged that will cut your boost in half instantly. Quote Link to comment Share on other sites More sharing options...
Mackpro Posted December 19, 2010 Share Posted December 19, 2010 Check the air compressor air intake tube that run around the back of the engine to the back of the intake manifold, the short rubber hose could have blown off, it happened to me. Quote Link to comment Share on other sites More sharing options...
fjh Posted December 19, 2010 Share Posted December 19, 2010 Check the air compressor air intake tube that run around the back of the engine to the back of the intake manifold, the short rubber hose could have blown off, it happened to me.Hey 68 He, mentioned he had no black smoke I was thinkin a fuel input issue!Do you have any intermitant or consistant Codes?? Quote Link to comment Share on other sites More sharing options...
Mackpro Posted December 19, 2010 Share Posted December 19, 2010 Hey 68 He, mentioned he had no black smoke I was thinkin a fuel input issue!Do you have any intermitant or consistant Codes??Didn't see that, what about over-tourqued injector hold downs, I have seen guys tighten them with a impact gun and collapse the injector body and they wont spray right? But I guess that would happen right after engine start up. Quote Link to comment Share on other sites More sharing options...
RowdyRebel Posted December 19, 2010 Share Posted December 19, 2010 what trans do you have? If it Is a Mack trans check to see the torque limit is un pluged that will cut your boost in half instantly.I've been having under-power issues myself. Where would I find that to see if it's unplugged? New turbo got me 5psi over what I had...but I'm still about 10psi short of where it SHOULD be... Check the air compressor air intake tube that run around the back of the engine to the back of the intake manifold, the short rubber hose could have blown off, it happened to me.That short rubber hose is oil-soaked on mine...like it's leaking oil out from there. Quote When approaching a 4-way stop, the vehicle with the biggest tires has the right of way! Link to comment Share on other sites More sharing options...
Gambi80 Posted December 20, 2010 Share Posted December 20, 2010 I've been having under-power issues myself. Where would I find that to see if it's unplugged? New turbo got me 5psi over what I had...but I'm still about 10psi short of where it SHOULD be... That short rubber hose is oil-soaked on mine...like it's leaking oil out from there. Gotta check that, long as your prodding and poking around, replace those short rubber hose pieces. Follow the steel hose around the back of the motor and feel for holes, chances are there'll be one on the passenger side near the top of the bellhousing...area. When it leaked it was around 22-25 max psi...replaced the hose it went to 30-35. Quote Ever wonder how a blind person knows when to stop wiping? Link to comment Share on other sites More sharing options...
Mackpro Posted December 20, 2010 Share Posted December 20, 2010 Check the muffler, I spent a day on a lowpower complaint and after checking everything I could think of I climbed up a ladder and with the engine running I could cap off and hold the exhaust back with my hand. The baffle had come loose and was stuck side ways inside the muffler. Quote Link to comment Share on other sites More sharing options...
theakerstwo Posted December 20, 2010 Share Posted December 20, 2010 Check the muffler, I spent a day on a lowpower complaint and after checking everything I could think of I climbed up a ladder and with the engine running I could cap off and hold the exhaust back with my hand. The baffle had come loose and was stuck side ways inside the muffler.I had same thing happen to me one time. Truck came in and it was a used truck but driver said he had it two months and ever time he had some time he put it in shop for a noise but no other problem being it was duel stack it was not hurting any thing. I and he drove it and when you would mash on the motor a sound that sound like a something was rolling across the floor of the bunk then it would lithy pop and no more noise untill you let up and it would do it again. I got a ladder and went up on top and found baffle loose. I was his hero for some time after that. Quote glenn akers Link to comment Share on other sites More sharing options...
montanacombineman Posted December 22, 2010 Author Share Posted December 22, 2010 It has the Mack 18spd tranny, there is an intake-sensor code, and coolant sensor code...where would the torque sensor be located? Quote Link to comment Share on other sites More sharing options...
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