Hard starting

[cerberusiam]

Nest question, did you phase the CP-3 correctly when it was installed?

 

[Darkbloodmon]

Nest question, did you phase the CP-3 correctly when it was installed?

Phase? I've read you can clock the gear in different positions (to quiet things down) but that it's not a timed pump, just as you can run a second one off a serp. belt like any other accessory drive.

 

[cerberusiam]

Yes, phase not time. There is a TSB on how to do it for best results. Out of phase creates NVH issues and can replicate quite closely injector knock causing unnecessary parts replacement. You want the CP-3 to be hitting TDC on a piston the same time the engine hits TDC for an injection event or the injection pulse can create and rattle\knock, gear slap noise in the IP drive gears.

 

[jghflys]

There is a TSB on how to do it for best results.

What is the TSB number?

 

[william lopoulos]

no, I did not phase it.... thought it all went too easy.... I could use the TSB as well

 

[cerberusiam]

https://mopar1973man.com/cummins/ar...on/engine/79_fuel_79/cp3-injection-pump-r524/

 

[william lopoulos]

nuts... well I can probably adjust the phase without removing the pump... just pop the gear and rotate the crank. Is there a hex nut on the crank?

 

[cerberusiam]

Yep, with a mirror and a little dexterity I think it can be done on the truck. Have another one to check with all the accessories on it. The other 2 were pulled apart to replace front main and timing cover seals so were a lot easier, one is still on the engine stand so it simplistic.

 

[jghflys]

nuts... well I can probably adjust the phase without removing the pump...

Always ask yourself, "what problem am I trying to fix." The cure may be worse than the disease. "Phasing" is of dubious origin. I have not seen any factory information on phasing. There are three pistons in the CP3 pump and it is used on 6 and 8 cylinder engines that have electronic injector timing so there will always be piston pulses that do not coincide with top dead center on the engines. So if the premise of phasing is correct there would actually be 3 acceptable positions 120 degrees apart for the CP3 shaft.

Also there are various markings on the end of the pump shaft so check it with a mirror or scope to determine which mark you will use to position the CP3 shaft. Also, check the position of the shaft with the engine at TDC, you may be OK already. You should have an engine barring tool, they cost about $30.

Turning the CP3 while on the engine: The fluid side of the pump is solid with diesel in the lines and pistons. As a minimum you will have to disconnect the fuel line outlet to turn it by hand. You already know that the access to the pump shaft is limited. Also the taper on the pump and the inside of the gear must be clean and dry when they are assembled. If the decision is to go ahead with the work I would remove the pump.

 

[cerberusiam]

Phasing of dubious origin? That is like saying the injector test procedures are of dubious origin, it just ain't so. The link is to a real Ram TSB for addressing a known NVH issue, not a DIY fix off of youtube.

Better do the math again on the phasing. There 6 cylinders on an ISB, 3 cylinders in a CP-3. Driven correctly and phased correctly there will ALWAYS be a CP-3 cylinder at TDC when and injector event happens. That is what the phasing accomplishes to stop the gear lash from injector pulse causing noise that leads to a lot if unnecessary investigation and parts replacement. The out of phase can and will emulate injector issues so close it is impossible to tell them apart. Multiple times people have replaced injectors to find that the noise is still there. As simple phasing like this has ZERO drawbacks.

The alternator can be used to get the engine to TDC and simply loosening the CP-3 to rail line negates the pressure in the pump. Set the pump at 9 o'clock as suggested with the gear loose, rotate the engine to TDC on #1 or #6 and it is phased. A can of carb cleaner sprayed on the CP-3 input and air dry will suffice to meet the requirements listed in the TSB. It ain't perfect but THIS is not rocket science. A lot of the impetus behind the removal and inspection is up sell, since the OP already has a new pump not an issue. Skipping the removal is not an issue unless there are other problems being chased, it won't hurt the engine by not following exactly some instructions.

 

[william lopoulos]

cerberusiam well stated my plan. Rotate the engine as is until the pump is at the proper angle, pop the gear free, rotate the engine to TDC and then retighten the gear. I will look into an engine-barring tool, that was my last concern. I need to remove the serpentine belt to get access to the hole cover. Though it is starting MUCH better, it is still not starting like it used to and "phasing" the pump seems like a low-risk move to try before replacing injectors (though they probably need to be done too.)

thank you

 

[jghflys]

The link is to a real Ram TSB for addressing a known NVH issue

What is the TSB number? CP3 is also used on 8 cylinder engines, how does that math work out?

 

[cerberusiam]

CP3 is also used on 8 cylinder engines, how does that math work out?

That is a good question. My response contains the answer indirectly, just not obvious.

Let me answer the question with a question: What difference does the number of cylinders make, be it 6 or 8 or 12 or 16?

In the context of the above; if every revolution of the engine is an injection event does the number of events matter?


This looks like an addendum to the FSM, not a normal TSB. I have found essentially the same instructions on multiple sites.

 

[william lopoulos]

If there are 3 cylinders inside the pump, then the number of cylinders in the engine must also be a multiple of 3 for the pump and engine cylinders to line up every time. Simple math. However, I would think that the rail itself would act as an accumulator and store pressure. There should be some ripple in the rail pressure, but how much?

It is still not starting as nicely as it should. I will try phasing the pump to see if it makes a difference and resolve this experimentally.

 

[cerberusiam]

Yes, there will be a ripple in the RP at injection event which translate to the injector pulse back to the CP-3. At an idle it is 500-600 psi, it may be a more with increased fuel flows. The RP ripple is another discussion entirely about injection quantity vs rail charge quantity per CP-3 charge event, injector return flow, CP-3 return, etc. If injection amount exceeds the capability of the CP-3 to maintain RP then you have a CP-3 flow problem, that will shows as large RP drop that never recovers. Draining the rail essentially.

The phasing is just making sure the CP-3 is charging the rail at the same time an injection event occurs to stop any gear lash in the CP-3. It could also contribute to RP drop at rpm. It is possible it may affect starting efficacy but it is one of several parameters that can influence start times. How many revolutions does the engine take to fire?

FYI, the multiples of 3 does not matter. The relationship of crank rotation to to CP-3 rotation is the only controlling factor.

 

[william lopoulos]

7 or 8 or so. Was 3 or years ago. Went to about 15 or more before I replaced the pump, had to stop after 8 or so cranks so as to not burn out the starter

 

[cerberusiam]

That is way too long, all things being equal if you are not getting fire after 2 revolutions and\or a slow 2 count you have issues somewhere. If the pump helped then you probably have worn injectors and\or PR valve.

 

[Darkbloodmon]

That is way too long, all things being equal if you are not getting fire after 2 revolutions and\or a slow 2 count you have issues somewhere. If the pump helped then you probably have worn injectors and\or PR valve.

Pretty sure my 03 factory service manual spec for turnover time was 4 secs. I keep this in mind for my driver logs, anything over or abnormal and I'm looking into something. But I agree that's way to many revolutions to turn over, something else on the system is worn.

 

[cerberusiam]

It takes 2 revs to synch the cam and crank sensor and should fire on the 3rd revolution so that sounds about right. When my son synched the CP-3 on his truck he said it started noticeably quicker so it seems that can make a difference in start up time, it always has started a bit slower than my truck but it is a manual and they seem to always take more revs than an auto truck to fire.

 

[william lopoulos]

So things have gotten worse. I really can't complain, 350,000 miles and very few engine issues. It is back to hard starting almost as bad as before. Haven't phased the pump yet, but I doubt that will help. Had to crank it 30 times yesterday to start it. Also, I am noticing very rough engine at idle. So I suspect injectors, correct? Where is the best place to get injectors at an affordable price? Not looking for extra high performance, just back to normal. Also do I need to replace the tubes as well? I assume I need a 1/4" drive torque wrench, anything else? Injector puller?

And will I be able to do it from above without removing the engine or mounts? I have seen videos on removing the valve cover, looks like that can be done without removing mounts. Please let me know, starting is getting very scary.

thanks
bill