12 Valve 2nd Gen Dodge Cummins 94-98 Discussion of 12 Valve 5.9 Liter Dodge Cummins Diesels with P7100 Injection Pumps

Low Power

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  #1  
Old 12-28-2012, 08:47 AM
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Default Low Power

My truck has stock level power or less, I have set timing to 16.5* put a brand new overflow valve, new fuel filter, new air filter, new 5x.013 injectors. Fuel pressure gauge getting around 34psi at idle and no less than 18 at full throttle. Getting 30psi out of the turbo, egts are at 900* Max at full throttle, there is black smoke when I floor it from a stop but it clears quickly and doesnt leave as much as it should. AFC is tuned with starwheel ff and smoke screw in about 2 or 3 turns. #0 Plate is at FF also tried no plate with no difference. Another strange thing is at idle I got a shake thats worse than stock, but not crazy, started after I put in a rebuilt tranny with the torque conveter from my sig. which is when i did all my mods. Valves are adjusted. I dont know what else to look at, any ideas or suggestions are greatly welcomed cause im stuck here, my truck is a slug compared to my brother in laws with very similar mods. I realize it could be the torque converter, but could that really cause such low power?
 
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Old 03-03-2013, 08:08 PM
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I also just put in a Airdog 2 165 with all new fuel lines so thats not the problem.
Anyone out there with a suggestion?
 
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Old 03-03-2013, 08:50 PM
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900* max??? that is freakin low. you arnt getting enough fuel? how many miles are on the truck? ever had the IP benched. did you install the GSK correctly? that could really be screwing you up. how many RPMS will the truck free rev to and rev to under a load? my first thought would be to look into the springs. could the shut down solenoid be binding and not coming all the way up?
 
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Old 03-03-2013, 09:00 PM
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i agree defenatly a low fuel issue. with those mods the truck should be leaving a fairly aggressive smoke signature. i had a similar issue with my fuel shut of solenoid not traveling all the way. it could be possible the new lift pump is not functioning properly. stranger things have happened

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there is also the tank module... the screen on the bottom could be clogged up
 

Last edited by olsmokey; 03-03-2013 at 09:00 PM. Reason: Automerged Doublepost
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Old 03-04-2013, 08:45 AM
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Trucks got 184,000miles, 900* max and thats with the egt probe pre-turbo. Does seem like a fuel problem. I havent had the pump benched yet and when we put in the gsk I followed the directions and set the springs to the specific height with a some of verniers. free rev I can get 3500 rpms and under load I can get up to about the same between 3000 and 3500 rpms. I have checked the fuel shut off before but it might be worth checking out again. The airdog is working I made sure to check that and when I installed the airdog this weekend I cleaned out the module completely and the screen is and was clean. So I will check the fuel shutoff, should I bring the Pump to a place and have it benched? I also found out why it shakes so bad as well, one of the motor mounts is blown. The only other things I can think of is bad compression.
 

Last edited by MechanicalDiesel; 03-04-2013 at 08:46 AM. Reason: blah
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Old 03-04-2013, 09:02 AM
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benching a pump is always nice but not needed. sometimes you can get the shakes from a pump that is way out of balance. that air dog should keep fuel pressure pretty dang constant from idle to full load. bump it up to 40psi and see if there is a difference.
 
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Old 03-05-2013, 08:47 AM
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No difference with more fuel pressure. It should be able to smoke pretty good, and its smoking like I got a stock fuel plate ff. This is driving me nuts.
 
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Old 03-05-2013, 11:25 AM
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have you checked the signal line to the afc? if its leaking it could be your whole problem
 
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Old 03-05-2013, 11:37 AM
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What are you calling the "smoke screw"?

On a p-pump, I am not aware of a smoke screw. There is the starwheel that adjust preboost fueling.

Verify that the govenor arm is not being caught under the fuel plate, that can cause it to run poorly. Also try sliding the AFC housing forward if it isn't already. Thay won't fix the problem but it might help.

Also with the Airdog you shouldn't see that much of a drop in pressure at WOT.... I believe that might be tje issue. Did you install the draw straw and 1/2" lines too?

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Old 03-05-2013, 01:46 PM
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I will check the afc line for leaks, yes the starwheel is ff and that "smoke screw" some call it, is the screw behind the afc thats under the little cover with 2 screws. I will also check the govenor arm but like posted above I went from no plate to 0 plate with no difference. AFC is ff and the pressure readings above were before I put in the airdog and with only the stock lift pump. Yes I put in the 1/2" inch lines and the upgraded fuel module with the draw straw.
 


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