Kman I hope you understand that I wasnt calling you a lier! I think I had some truth in that too, I said that these newer trucks had a higher demand for fuel at WOT, knowing that those #s where not a bad thing on a track. But I didnt know at crusing speed that around 20k to say 24k was that bad. But now we all know.
Thanks DON,

 

No I was not talking about you. You and bluechrome both made valid points. I still have to agree that filtration is the number 1 killer of injectors like you and bluechrome said, pressure just adds to the mix. I will agree I was not 100 percent sure about it when I said it so could not back it up but now I know for sure it is bad.

 

So what does the stage 2 or three cp3 raise the preassure to? Or does a modified pump raise it at all at cruise speeds?

 

Don, is this back leak you are talking about what is measured when you do an injector return flow test? If so this would be an easy way to quantitate the health of the injector bodies wouldn't it? For those that don't know, the return flow test I am talking about is the one where you use the adapter on the back on the fuel filter housing that separates cp3 from injector return back to the fuel tank. I think max allowable is 180 ml. per minute or about 30 ml. per minute per injector. Thanks Don, Jay

 

The modded pump will only supply what is commanded. So if you are using the stock pressure tuning you will only see stock pressure. The pressure boxes fool the truck into commanding more pressure, thereby more pressure is supplied if the cp3 can keep up.

 

Thanks for the explanation that makes sense but with the FCA and other parts drilled out I was just assuming it would still increase.

 

The drilled out parts will allow more flow at given pressures and when more pressure is commanded, but the actual pressure values are managed in the ecm. Even if the pump is capable of supplying high amounts of pressure the ecm limits it to the programmed parameters.

 

Maybe. Just thinking out load here, so don't unload on me if this is wrong. What if you have a capped RV/or not - don't know? The cp3 is mechanical. It is driven by mechanics. If you increase the flow, essentially you are increasing the volume of fuel it is pumping. The fuel has to go somewhere. If you have increased the mechanical output so that it flows more at a given rpm, I would think it could stand to reason that at cruising rpms, the pump is actually pumping more volume than it was stock. More volume = more pressure. If the pressure doesn't go up simply because of a modded pump, where does the excess fuel go? What exactly does the ecm control in the cp3 and its function?

 

the ECM sees from the rail pressure sensor what the CP3 is producing for pressure and adjusts the FCA to bring the Rail pressure to where the ECM wants it for conditions. if you increase flow then the ECM will see the requested pressure and start closing the FCA sooner and more to maintain the same pressure as the unmodded pump.

 

The fuel is metered as it enters the pump by the FCA, and rail pressure is read in the rail through the rail pressure sensor. The ECM reads rail pressure and controls the amount of fuel metered by the FCA, therefore despite the pump's capability to flow the ecm can control the amount of fuel pressure in the rail by metering the amount of fuel flowing through the pump. That is why when you plug a pressure box into the rail sensor it is able to alter the RP signal to command more fuel from the FCA.

The RV really has no effect until rail pressure has exceeded the maximum limit and blows through. At cruising speeds it should remain closed. If not, it leaks and should be replaced.

 

Great something else to worry about. I have been running Beta 4.2 for a long time. After lots of driving and trying different programs on my truck it is the best driving, easiest to control smoke, least haze, and fastest lighting program I have found. Problem is I see 9000 at idle, and if you touch the accelerator it goes up to 20-21K. Now it doesnt seem to spike it just moves up rather quickly. At any speed if you touch the throttle 20-21K if you hit it a bit harder 23-24K. So what I am reading now is my injectors are on borrowed time, great I already have 2 sets at a small fortune. And my one set will flow/bench test perfect but will not run right in the truck. Guess its time to call Tim and see if he recommends a different Smarty file for DD. Heck my truck has run so good over the last year I may just let her eat, if it aint broke dont fix it. What would U do, any suggestions???????

 

Yes, that is the dealership technicians way to measure back leak. (-:

 

The stock relief valve is good at relieving pressure when you quickly release your foot from the throttle. A blocked/capped valve cant do this, so you can get a high pressure "blip"

The problem is the stock relief valve is prone to failure with added volume and pressure, so blocking it is a quick way to get around that.

 

Don,

what are signs of a bad relief valve?

 

There are lots of different symptoms depending on how screwed up it is. Some wont start and others just seem to feel doggy drivin around. Less power all the time as it gets weaker. Just take the bolt out of the top and see if there is fuel in it. Dry it out and start the truck if you get fuel its shot.