Rob Posted March 4, 2012 Share Posted March 4, 2012 One of the trucks I've not got home yet is hard to start unless shooting some silicone into the intake plumbing. It then fires but is down on power from normal. This truck has been going downhill for sometime as far as power but does not seem to burn oil. This hard start situation is new however, (I'm told). The filters and lines are all checked and changed so I'm thinking something in the injection cycle is weak. I've never been around Cummins and not familar with the PT style pump. I'm told the engine is a 400 and the chassis is a 1974, but I don't know if the engine is original to the chassis, or later. The aluminum tag is gone from the geartrain cover.Anything else to check before tearing things apart? I'd like to drive it home as it's only about 140 miles south from me but certainly don't want to get stranded.Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment https://www.bigmacktrucks.com/topic/23617-hard-starting-cummins/ Share on other sites More sharing options...
bullhusk Posted March 4, 2012 Share Posted March 4, 2012 One of the trucks I've not got home yet is hard to start unless shooting some silicone into the intake plumbing. It then fires but is down on power from normal. This truck has been going downhill for sometime as far as power but does not seem to burn oil. This hard start situation is new however, (I'm told). The filters and lines are all checked and changed so I'm thinking something in the injection cycle is weak. I've never been around Cummins and not familar with the PT style pump. I'm told the engine is a 400 and the chassis is a 1974, but I don't know if the engine is original to the chassis, or later. The aluminum tag is gone from the geartrain cover.Anything else to check before tearing things apart? I'd like to drive it home as it's only about 140 miles south from me but certainly don't want to get stranded.RobRob, Water is the Cummins PT (Pressure timed) pumps biggest culprit, if the RPM's don't return, and sort of just float? thats a sign that the pump is going bad. Also if the RPM's don't max out, thats also sometimes pump trouble! As far as going 140 miles ? I don't know ?? I've driven some of these Cummins powered trucks for months with these symptoms so I guess it's a crap-shotGood Luck Ernie DS Quote Link to comment https://www.bigmacktrucks.com/topic/23617-hard-starting-cummins/#findComment-105520 Share on other sites More sharing options...
umodelnut Posted March 4, 2012 Share Posted March 4, 2012 tell the guy to put a mack motor in it!!! LOL Quote Link to comment https://www.bigmacktrucks.com/topic/23617-hard-starting-cummins/#findComment-105527 Share on other sites More sharing options...
Rob Posted March 4, 2012 Author Share Posted March 4, 2012 tell the guy to put a mack motor in it!!! LOL That is already in the cards if this Cummins is needing much.Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment https://www.bigmacktrucks.com/topic/23617-hard-starting-cummins/#findComment-105548 Share on other sites More sharing options...
Rob Posted March 4, 2012 Author Share Posted March 4, 2012 Rob, Water is the Cummins PT (Pressure timed) pumps biggest culprit, if the RPM's don't return, and sort of just float? thats a sign that the pump is going bad. Also if the RPM's don't max out, thats also sometimes pump trouble! As far as going 140 miles ? I don't know ?? I've driven some of these Cummins powered trucks for months with these symptoms so I guess it's a crap-shotGood Luck Ernie DSHi Ernie and thanks, It does fire right off with a sniff of either silicone spray, or ether and runs well at idle but as mentioned is very sluggish in response and severely down on power recently. This is another RS700 w/nine speed and it has always run/pulled well, but the hard start issue is about to put it down. I purchased it last year and then the former owner's newer truck deal fell apart so I let him retain it till replaced with another truck.Is there a sump on that pump that could be drained or checked for water contamination? I'm assuming it is water cooled, or are you talking water contamination in the fuel? Either way it sounds like the pump and nozzles need to go into the shop.Thanks,Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment https://www.bigmacktrucks.com/topic/23617-hard-starting-cummins/#findComment-105550 Share on other sites More sharing options...
bullhusk Posted March 4, 2012 Share Posted March 4, 2012 Hi Ernie and thanks, It does fire right off with a sniff of either silicone spray, or ether and runs well at idle but as mentioned is very sluggish in response and severely down on power recently. This is another RS700 w/nine speed and it has always run/pulled well, but the hard start issue is about to put it down. I purchased it last year and then the former owner's newer truck deal fell apart so I let him retain it till replaced with another truck.Is there a sump on that pump that could be drained or checked for water contamination? I'm assuming it is water cooled, or are you talking water contamination in the fuel? Either way it sounds like the pump and nozzles need to go into the shop.Thanks,RobWater in the fuel, also a lot of the Cummins power trucks came with one fuel filter, I know most of the A-Cars we had only came with one fuel filter. Just pull the fuel filter an see if there is water on the bottom, also let the truck over night and drain the fuel tanks and see if water comes out. It's been a long time now, but I think your gonna need an inch pound torque wrench to put the injectors back in an re-adjust the top end of the motor. If it's an NTC-400 BC-I ithink I have all the spec's some placeErnie DS Quote Link to comment https://www.bigmacktrucks.com/topic/23617-hard-starting-cummins/#findComment-105560 Share on other sites More sharing options...
Brian Blaylock Posted March 4, 2012 Share Posted March 4, 2012 Rob I know you have said before but where do you live? My dad had a couple of old Mack's with 350 cummins in them if the temp got below 50 degrees you better have them plugged in or have a can of smelling salts to wake them up Quote Link to comment https://www.bigmacktrucks.com/topic/23617-hard-starting-cummins/#findComment-105562 Share on other sites More sharing options...
theakerstwo Posted March 4, 2012 Share Posted March 4, 2012 If there is water in the fuel it would be missing other things but you can drin the fuel filter to check. Sounds like it may be lossing its fuel prime. First thing to do is find the elbo fitting on top of the gear pump which is restricted check valve and a quick check can be made. Remove the elbo and rap your lips alrond it and see if you can blow either way thru it.If you can replace it. If ok then move on and put a hose in a bucket of fuel and start it and let it set over night in the fuel and start again to see if its solid. If not then check for sucking airby making you a simple clear plastic clear tube. Use part of a # 10 swiel and clamp a clear hose that you can get at the lunmber yard on the swivel and install in line at the fuel pump on the suppy. Smear some luber plate grease on the week hole on the front drive shaft housing and some fuel inside of tach drive. With the engine running maybe 1000 rpm watch for bubbles thru the clear supply hose and if some repair. Also With engine running same way bend the clear hose over trying to cut the supply off for the pump.Watch the fuel in the tach and id it drops down then replace the tach drive and seals. If the grease is sucked in the front cover then replace the front seal.Also make sure it is not low voltage to the shut down switch by screwing the manual screw and see if it starts better. glenn Quote glenn akers Link to comment https://www.bigmacktrucks.com/topic/23617-hard-starting-cummins/#findComment-105563 Share on other sites More sharing options...
Rob Posted March 4, 2012 Author Share Posted March 4, 2012 Rob I know you have said before but where do you live? My dad had a couple of old Mack's with 350 cummins in them if the temp got below 50 degrees you better have them plugged in or have a can of smelling salts to wake them upI'm 20 miles west of Peoria between Canton and Farmington on rt. 78. This truck doesn't want to start if it is in the mid 60's. It is physically outside of Pana and kept inside. It's replacement is a day cab CH and appears to be a really nice truck. I can run down with a drop deck in the future but our family reunion, (around Effingham) is in the late summer and I may drive it home then.Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment https://www.bigmacktrucks.com/topic/23617-hard-starting-cummins/#findComment-105564 Share on other sites More sharing options...
Rob Posted March 4, 2012 Author Share Posted March 4, 2012 If there is water in the fuel it would be missing other things but you can drin the fuel filter to check. Sounds like it may be lossing its fuel prime. First thing to do is find the elbo fitting on top of the gear pump which is restricted check valve and a quick check can be made. Remove the elbo and rap your lips alrond it and see if you can blow either way thru it.If you can replace it. If ok then move on and put a hose in a bucket of fuel and start it and let it set over night in the fuel and start again to see if its solid. If not then check for sucking airby making you a simple clear plastic clear tube. Use part of a # 10 swiel and clamp a clear hose that you can get at the lunmber yard on the swivel and install in line at the fuel pump on the suppy. Smear some luber plate grease on the week hole on the front drive shaft housing and some fuel inside of tach drive. With the engine running maybe 1000 rpm watch for bubbles thru the clear supply hose and if some repair. Also With engine running same way bend the clear hose over trying to cut the supply off for the pump.Watch the fuel in the tach and id it drops down then replace the tach drive and seals. If the grease is sucked in the front cover then replace the front seal.Also make sure it is not low voltage to the shut down switch by screwing the manual screw and see if it starts better. glennThanks Glenn, I remember your advice from another problem with the clear tubing for another gent. I'll be down there next weekend and will get some time with it. I've driven the truck and it ran really well at the time. I understand it still runs well, just down on power from it's usual self. Hi is going to pull the wet kit later this week to install onto the new truck and then it will be ready to pickup but can stay where it is also but probably outside.Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment https://www.bigmacktrucks.com/topic/23617-hard-starting-cummins/#findComment-105566 Share on other sites More sharing options...
Joe Ditchkus Posted March 4, 2012 Share Posted March 4, 2012 Rob along with hard starting does it not rev up properly or idle back down slowly? I had that problem on a Cummins with PT Pump and pump had to be rebuilt. Joe D. Quote Link to comment https://www.bigmacktrucks.com/topic/23617-hard-starting-cummins/#findComment-105572 Share on other sites More sharing options...
b61mack Posted March 5, 2012 Share Posted March 5, 2012 One of the trucks I've not got home yet is hard to start unless shooting some silicone into the intake plumbing. It then fires but is down on power from normal. This truck has been going downhill for sometime as far as power but does not seem to burn oil. This hard start situation is new however, (I'm told). The filters and lines are all checked and changed so I'm thinking something in the injection cycle is weak. I've never been around Cummins and not familar with the PT style pump. I'm told the engine is a 400 and the chassis is a 1974, but I don't know if the engine is original to the chassis, or later. The aluminum tag is gone from the geartrain cover.Anything else to check before tearing things apart? I'd like to drive it home as it's only about 140 miles south from me but certainly don't want to get stranded.Rob Rob when they came out with low sulfer fuel it seems like the older cummins were the worst for the O rings in the pump going bad, that fuel ate them up. every time i fill up i put Howes in my B61 just in case. there should be a little tag on top of the fuel pump around the tach drive that had the model number like (NTC- 350). Ron Quote Link to comment https://www.bigmacktrucks.com/topic/23617-hard-starting-cummins/#findComment-105616 Share on other sites More sharing options...
Rob Posted March 5, 2012 Author Share Posted March 5, 2012 Rob along with hard starting does it not rev up properly or idle back down slowly? I had that problem on a Cummins with PT Pump and pump had to be rebuilt. Joe D.I can't answer first hand but from the description is does both of what you mention. I'll see it this weekend.Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment https://www.bigmacktrucks.com/topic/23617-hard-starting-cummins/#findComment-105622 Share on other sites More sharing options...
Rob Posted March 5, 2012 Author Share Posted March 5, 2012 Rob when they came out with low sulfer fuel it seems like the older cummins were the worst for the O rings in the pump going bad, that fuel ate them up. every time i fill up i put Howes in my B61 just in case. there should be a little tag on top of the fuel pump around the tach drive that had the model number like (NTC- 350). RonI'll certainly get a look. I didn't know how to identify a Cummins without the plat or sticker.Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment https://www.bigmacktrucks.com/topic/23617-hard-starting-cummins/#findComment-105623 Share on other sites More sharing options...
GreenGiant2 Posted March 5, 2012 Share Posted March 5, 2012 there is a stamping on the block on upper driver side near head. this is id. #. call cummins and they will tell you what it is and size and year. also tag on pump will give you the cpl code and engine size.. example,,, mine is a ntc 350 BC and my cpl code is a 632, this tells the pump shop what injectors the engine was set up with and ect....gg2 Quote We the unwilling, Lead by the unqualified, are doing the impossible, for the ungrateful. Link to comment https://www.bigmacktrucks.com/topic/23617-hard-starting-cummins/#findComment-105627 Share on other sites More sharing options...
theakerstwo Posted March 5, 2012 Share Posted March 5, 2012 Rob the engine # is a 8 digit # at the rear on a later engine but rear below the heads of the block and give to me and i have cummins quick ser here so i can get the CPL # for you and HP. glenn Quote glenn akers Link to comment https://www.bigmacktrucks.com/topic/23617-hard-starting-cummins/#findComment-105630 Share on other sites More sharing options...
Rob Posted March 5, 2012 Author Share Posted March 5, 2012 Rob the engine # is a 8 digit # at the rear on a later engine but rear below the heads of the block and give to me and i have cummins quick ser here so i can get the CPL # for you and HP. glennThanks Glenn, I'll be nice to get a rundown on it. I've been told the engine has been "inframed" at one time but not much more.Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment https://www.bigmacktrucks.com/topic/23617-hard-starting-cummins/#findComment-105633 Share on other sites More sharing options...
GreenGiant2 Posted March 5, 2012 Share Posted March 5, 2012 if it is a 74, the big cam wasnt out yet, may be a 335 small cam.gg2 Quote We the unwilling, Lead by the unqualified, are doing the impossible, for the ungrateful. Link to comment https://www.bigmacktrucks.com/topic/23617-hard-starting-cummins/#findComment-105665 Share on other sites More sharing options...
Frmconcrete09 Posted March 5, 2012 Share Posted March 5, 2012 We have a freightshaker with a big cam cummins that did the same thing and was leaking fuel around the front of the pump, scheid diesel in effingham rebuilt it and it ran like a new truck, which was pretty amazing since the truck has well over 1 million when the odometer quit working Quote Link to comment https://www.bigmacktrucks.com/topic/23617-hard-starting-cummins/#findComment-105672 Share on other sites More sharing options...
Rob Posted March 5, 2012 Author Share Posted March 5, 2012 We have a freightshaker with a big cam cummins that did the same thing and was leaking fuel around the front of the pump, scheid diesel in effingham rebuilt it and it ran like a new truck, which was pretty amazing since the truck has well over 1 million when the odometer quit workingI had a cousin, (in law) that worked at Scheid for a while. Very nice people and into hot rodding diesel engines. I purchased a couple of turbocharger kits from them for the natural 7.3 ltr engines in Ford pickup trucks, then had them go through the injection pumps and "tweak" them a little bit. My cousin now works for the International delership but when he left Scheid to go to work at the Peterbilt dealership, we had some very interesting conversations.......Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment https://www.bigmacktrucks.com/topic/23617-hard-starting-cummins/#findComment-105680 Share on other sites More sharing options...
Rob Posted March 5, 2012 Author Share Posted March 5, 2012 if it is a 74, the big cam wasnt out yet, may be a 335 small cam.gg2I pulled the title out of the file, the truck is a 75 model year.Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment https://www.bigmacktrucks.com/topic/23617-hard-starting-cummins/#findComment-105681 Share on other sites More sharing options...
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