Icehole Posted July 20 Share Posted July 20 Had to haul a few loads in my 90 R Model and quickly realized it's gutless. Has a 400hp E7, 12 speed, top loader rears. All it can do, foot to floor, to hit 55mph on flat road. Any grade it slows quick. Had maybe 15k in the bed, if that, was mix of light topsoil, sawdust and wood bits. Ideas were I should start? It seems to have an exhaust manifold leak at the last cylinder, maybe last 2, but not severe. Can just to say hear it and signs of soot. EGT seems fine I guess, but not sure if the gauge is correct. Highest I saw was maybe 700* Thinking to get a cheap boost gauge to check that, what is normal boost? Otherwise maybe due an overhead, and something is up with the pump? It has about 8000hrs, so shouldn't be tired. I've run several dump truck with 2-3x the hours that pulled well. Quote Link to comment https://www.bigmacktrucks.com/topic/74363-low-power-e7/ Share on other sites More sharing options...
Icehole Posted July 20 Author Share Posted July 20 55mph is around 1700-1800rpm so don't think it's a governor issue. I got it to almost 65 at one point, just took forever. Quote Link to comment https://www.bigmacktrucks.com/topic/74363-low-power-e7/#findComment-555599 Share on other sites More sharing options...
Joey Mack Posted July 20 Share Posted July 20 check to see if there is 'play' in the throttle linkage.. the lever on the injection pump may be loose as well,, my BET is slop in the linkage from the pedal to the inj. pump. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/74363-low-power-e7/#findComment-555600 Share on other sites More sharing options...
Popular Post fjh Posted July 20 Popular Post Share Posted July 20 15 minutes ago, Joey Mack said: check to see if there is 'play' in the throttle linkage.. the lever on the injection pump may be loose as well,, my BET is slop in the linkage from the pedal to the inj. pump. Also check the stop to Mack sure it’s going all the way on! 2 1 Quote Link to comment https://www.bigmacktrucks.com/topic/74363-low-power-e7/#findComment-555601 Share on other sites More sharing options...
Icehole Posted July 21 Author Share Posted July 21 2 hours ago, Joey Mack said: check to see if there is 'play' in the throttle linkage.. the lever on the injection pump may be loose as well,, my BET is slop in the linkage from the pedal to the inj. pump. There's play but I have it that pump is WOT before pedal bottoms out. Quote Link to comment https://www.bigmacktrucks.com/topic/74363-low-power-e7/#findComment-555605 Share on other sites More sharing options...
Joey Mack Posted July 21 Share Posted July 21 replace the fuel filters, that is often the first thing to do with a low power complaint.. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/74363-low-power-e7/#findComment-555606 Share on other sites More sharing options...
JoeH Posted July 21 Share Posted July 21 +1 on fuel filters. You need boost gauge also. Should at least be hitting 30 psi. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/74363-low-power-e7/#findComment-555610 Share on other sites More sharing options...
Icehole Posted July 22 Author Share Posted July 22 23 hours ago, Joey Mack said: replace the fuel filters, that is often the first thing to do with a low power complaint.. They are almost new. Have maybe 2 hours, if that, on them. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/74363-low-power-e7/#findComment-555645 Share on other sites More sharing options...
Icehole Posted July 22 Author Share Posted July 22 11 hours ago, JoeH said: +1 on fuel filters. You need boost gauge also. Should at least be hitting 30 psi. Ok. Info im finding is 23-25psi max Quote Link to comment https://www.bigmacktrucks.com/topic/74363-low-power-e7/#findComment-555646 Share on other sites More sharing options...
Popular Post JoeH Posted July 22 Popular Post Share Posted July 22 There's your problem. My e7-350 hits 30, and in the right circumstances I've hit 34 psi. Wheres your pyrometer peaking? 700 I thought you said? Sounds like you're under fueling. Get your filters changed, check/replace your fuel supply lines. Fuel suction lines can come apart internally, closing off the line internally under suction pressure. You should also check your fuel supply pump. If your pyro is running hot, 1000°+, then I'd suspect air problems, i.e. boost leak. 3 Quote Link to comment https://www.bigmacktrucks.com/topic/74363-low-power-e7/#findComment-555648 Share on other sites More sharing options...
fjh Posted July 22 Share Posted July 22 11 hours ago, JoeH said: There's your problem. My e7-350 hits 30, and in the right circumstances I've hit 34 psi. Wheres your pyrometer peaking? 700 I thought you said? Sounds like you're under fueling. Get your filters changed, check/replace your fuel supply lines. Fuel suction lines can come apart internally, closing off the line internally under suction pressure. You should also check your fuel supply pump. If your pyro is running hot, 1000°+, then I'd suspect air problems, i.e. boost leak. Lack of Fuel in my opinion as well ! l Check all the simple stuff first ! Fuel tank vent lines and hoses to the pump ! Also if the smoke limiter has a hole in the diaphragm it will be low on juice! if you can remove the line to the limiter and blow or suck on it if it wont hold a vacuum or you can blow thru it has a hole in it! 2 Quote Link to comment https://www.bigmacktrucks.com/topic/74363-low-power-e7/#findComment-555675 Share on other sites More sharing options...
Icehole Posted July 23 Author Share Posted July 23 (edited) On 7/21/2024 at 6:14 PM, JoeH said: There's your problem. My e7-350 hits 30, and in the right circumstances I've hit 34 psi. Wheres your pyrometer peaking? 700 I thought you said? Sounds like you're under fueling. Get your filters changed, check/replace your fuel supply lines. Fuel suction lines can come apart internally, closing off the line internally under suction pressure. You should also check your fuel supply pump. If your pyro is running hot, 1000°+, then I'd suspect air problems, i.e. boost leak. The info I'm finding is saying 23-25psi max is normal. No idea what the engine is doing, don't have a gauge yet. Fuel Filters are new. No idea if the pyro is correct, I've never run anything with the sensor after the turbo. Dumb place for it. Edited July 23 by Icehole Quote Link to comment https://www.bigmacktrucks.com/topic/74363-low-power-e7/#findComment-555724 Share on other sites More sharing options...
Icehole Posted July 23 Author Share Posted July 23 13 hours ago, fjh said: Lack of Fuel in my opinion as well ! l Check all the simple stuff first ! Fuel tank vent lines and hoses to the pump ! Also if the smoke limiter has a hole in the diaphragm it will be low on juice! if you can remove the line to the limiter and blow or suck on it if it wont hold a vacuum or you can blow thru it has a hole in it! Talking about the fuel aneroid, aka afc? Quote Link to comment https://www.bigmacktrucks.com/topic/74363-low-power-e7/#findComment-555725 Share on other sites More sharing options...
fjh Posted July 23 Share Posted July 23 10 hours ago, Icehole said: Talking about the fuel aneroid, aka afc? yes Quote Link to comment https://www.bigmacktrucks.com/topic/74363-low-power-e7/#findComment-555732 Share on other sites More sharing options...
Mackpro Posted July 23 Share Posted July 23 If power loss has been gradual over the years. I’d look at getting the pump timing adjusted. Timing gear train wear over time will cause the pump timing to slowly retard. I’ve seen them as much as 2 degrees below spec. I alway set them 1 to 1.5 degrees over the spec on the valve cover. Being in a RD I’d only go 1 degree over spec. CH’s and Superliners with the bigger radiators can go 1.5 degrees over. Also check you muffler. Some of the older RD’s had those small canisters mufflers that broke apart inside. And like the guys said above. Check linkage for full throttle and especially the kill leverage way forward. Chased a low power issue for over a day one time and it was the kill lever not adjusted. Also if truck has an air ride cab , be sure to check the linkage with the cab aired up. Check air filter for being put in upside down( don’t think it will even run that way though) 2 Quote Link to comment https://www.bigmacktrucks.com/topic/74363-low-power-e7/#findComment-555739 Share on other sites More sharing options...
Icehole Posted July 24 Author Share Posted July 24 On 7/23/2024 at 6:37 AM, Mackpro said: If power loss has been gradual over the years. I’d look at getting the pump timing adjusted. Timing gear train wear over time will cause the pump timing to slowly retard. I’ve seen them as much as 2 degrees below spec. I alway set them 1 to 1.5 degrees over the spec on the valve cover. Being in a RD I’d only go 1 degree over spec. CH’s and Superliners with the bigger radiators can go 1.5 degrees over. Also check you muffler. Some of the older RD’s had those small canisters mufflers that broke apart inside. And like the guys said above. Check linkage for full throttle and especially the kill leverage way forward. Chased a low power issue for over a day one time and it was the kill lever not adjusted. Also if truck has an air ride cab , be sure to check the linkage with the cab aired up. Check air filter for being put in upside down( don’t think it will even run that way though) I'm not sure on gradual, I bought it 2 years ago and this is the first load it hauled. Quote Link to comment https://www.bigmacktrucks.com/topic/74363-low-power-e7/#findComment-555804 Share on other sites More sharing options...
Icehole Posted November 13 Author Share Posted November 13 Moved it last night to park for the winter and noticed it cranks "choppy" like it's got less compression in a cylinder or two. Like a waa waa waa wa waa wa. That typical? I've run some equipment that it was just how the starter was. Aside from the low power it starts fine, idles fine, I think. It vibrates the cab, but isn't much worse than the much newer trucks I've run. Little bit of smoke when cold, but nothing unusual. Like last night it was maybe 10* Does take 15-20+ seconds of cranking for the first start if it sits for a while. Was probably last started 3 months ago. Quote Link to comment https://www.bigmacktrucks.com/topic/74363-low-power-e7/#findComment-561884 Share on other sites More sharing options...
Icehole Posted November 13 Author Share Posted November 13 Usually with a dead cylinder it'll be pretty hard to start, especially when cold,, and idle/run bad, at least in my experience Quote Link to comment https://www.bigmacktrucks.com/topic/74363-low-power-e7/#findComment-561885 Share on other sites More sharing options...
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