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

injector knock?

  #1  
Old 09-09-2014, 04:54 PM
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Default injector knock?

I have a 99 ppump 24v didn't know if I should post here or what. rebuilt the engine awhile back we couldn't get a sheet on timing so we set the timing where we thought it was best, at idle you cant really hear the knocking or rattle but as you accelerate you can hear it and you can hear it best going under a bridge or next to jersey barriers or a tractor trailer on highway, the injectors were in the truck when I got it and it didn't have the knock like it does now after we rebuilt the engine its not a rod knock or bearing. I was going to pull out the injectors to have them pop tested but was wondering what the bar should be set at for the p7100. the pump has work done and flows around 600cc of fuel and injectors are 7x16 sac "billet bodies".
 
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Old 09-09-2014, 05:02 PM
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Also really only does it when in gear with a load on the engine
 
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Old 09-09-2014, 07:10 PM
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you seriously spent all this money and guessed on pump timing???
has the timing tab been changed in the pump or is it set to stock timing?
you didnt pin time it or set it with a gauge? im baffled in your thinking.
if you have a god awful amount of timing it will be hard starting hase white and rattle ALOT unless you are WAY up in the RPMS.

i set my injectors between 160 and 180 bar depending on the application

kinda rare for these style injectors to fuel knock as they are mechanical and have to really really F-up to start dumping fuel instead of a solenoid issue like the newer stuff. they normally leak or have poor chatter or spray pattern causing misses and excess smoke/loss of power issues. stuck open injectors will make you tow the truck home, like OMG what is wrong with the truck shut the key off kinda stuff.

i vote properly set your timing and enjoy. around 20* for a hot street truck.
 

Last edited by turbo2332; 09-09-2014 at 07:12 PM.
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Old 09-10-2014, 05:43 AM
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Not pin timed. Not hard to start it hazes white while idling and cruising down the highway. It didn't do this before I rebuilt the engine. I was going to pull out the injectors cause it cost 7 dollars to bar test them which is cheap. At idle like I said not to chattery and can't hear a knock even when I bring up the rpm in park or neutral when u put it into gear and have a load on the engine and start on the throttle is when you have the problem. And wen under a bridge or whatever sounds more like comming from the passenger side of the rig
 
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Old 09-10-2014, 05:44 AM
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We set it with a dial indicator
 
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Old 09-10-2014, 03:12 PM
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thats fine , i do too. what did you set it to? are these injectors new? you said billet bodies i can only assume they dont have bunches of miles on them
 
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Old 09-11-2014, 12:01 AM
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I would say .. Your timing is way too high .. You need to time it right .. 20* should be a good starting point ..
 
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Old 09-11-2014, 04:35 AM
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injectors are not new, have had them for awhile.. like I said we do not know where the timing is atm because we could not find a chart for the pump this pump, we set it to where it sounded best at an idle going to reset tomorrow. Ive been told if it hazes on the highway its way to high.
 
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Old 09-11-2014, 02:43 PM
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ya theres your problem. set to .000's of an inch and you guessed
 
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Old 09-11-2014, 11:16 PM
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yeah too much timing will cause you to actually hear each injector/cumbustion event ..

.. Unless you are going to spin it to like 5K ..

P-Pump Timing Chart - Competition Diesel.Com - Bringing The BEST Together

This thread will give you all the Info you need .. .. Keep us posted
 

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