LLY: 85 over cp3. Sounds like a ford

GMC_2002_Dmax

GMC_2002_Dmax

The Still Master
Feb 15, 2008
1,748
8
38
55
Charleston, SC
www.ridgerunnerdieselperformance.com
CP3 Pump Operation

For those who do not know how a CP3 works let me explain.

1) The CP3 uses a regulator to let fuel in or out of the CP3 by altering the MA-milliamps of voltage.

2) Absent any voltage to the CP3 the spring will force the regulator wide open, the voltage closes the regulator and the spring opens it, it is easier to pull a spring closed and then allow it to expand. This also allows fuel to flow if a regulator fails.

3) It is a precision pump, it has tolerences down to the thousandths so opening up internal passages and regulator triangles with a die grinder and drill bit is hardly precision machining.

Anyone who wants WOT/Full flow only needs to put a simple open/closed switch from the ecm to the regulator or when you go WOT it will cut power to the CP3 and it will then go to full open.

This can be done with a relay and DSP output with efi live as well.

OLD SCHOOL........also if you command 0 amps in efi live ( which I do ) in the amperage tables it should in theory ( it does ) open the regulator wide open.

;)
 
coker6303

coker6303

Keep Calm and Chive On!!
Aug 6, 2009
2,484
0
36
40
Houston, TX
Spring return fail open on the supply of the CP3? Interesting, learn something new everyday!

I'm assuming it is regulating based on pressure feedback, but resistance to flow is pressure. So at light and mid range throttle it is just regulating CP3 supply flow enough to maintain desired rail psi?

---------------------------------
08 Chevy LMM CCSB
trans by Relentless Diesel
EFILive tuning by JoshH
554hp 1014ft-lbs 7/30/11
 
Gmclbz

Gmclbz

New member
Jul 8, 2008
1,048
0
0
www.upstatedieselperformance.com
DIESELMAFIAPER.LB7 said:
There 85% over pump cant even fuel my 45% overs i gained 1000 psi from my 244k miles lb7 pump to a new 85% over pump (17k up to 18k). Brady said that "he couldnt believe his guys sold a small pump for big nozzles" those are his exact words. He was willing to give me a deal on a 120% pump but a ppe twin cp3 kit went on instead. I also used my old pump in the twin cp3 kit with there modded pump so we'll see how there pump lasts.
Click to expand...

How big of a pw?
 
PAT

PAT

EASY DAY
Aug 21, 2011
1,100
0
0
your back yard
DIESELMAFIAPER.LB7 said:
At the same pw of 2100 i didnt change any fueling just swapped pumps well i tuned the regulator table for better idle ect. I now have a 2400 pw with my twin cp3 kit holds desired rail
Click to expand...

I'm running the same pw (2400) and it doesn't hold psi at all. :( I ran the same pw with the stock cp3 and it held. For a month. Then the cp3 gave out and held 10k Rp lol
 
THEFERMANATOR

THEFERMANATOR

LEGALLY INSANE
Feb 16, 2009
3,890
44
48
44
ZEPHYRHILLS, FL
PAT said:
I'm running the same pw (2400) and it doesn't hold psi at all. :( I ran the same pw with the stock cp3 and it held. For a month. Then the cp3 gave out and held 10k Rp lol
Click to expand...

Have you stopped to think that maybe theres a reason the 2 pumps now cannot hold rail pressure? Your stock one quit holding pressure, so you put on a new one that also isn't holding rail pressure. You could have debris caught in the rails from the failed CP3, or you could have a supply problem to the CP3. Don't automatically assume that your old CP3 just died, and a pump swap will fix it. And the regulator works like Tony said. In the absence of voltage to it it goes full open allowing max fuel flow to the CP3. As it adds milliamps to the regulator it pulls the valve open restricting the flow of fuel to the CP3. It does not need full flow of fuel to reach max pressure at idle, ESPESCIALLY not with an oversized pump. And disconnecting the regulator with the pop off blocked could easily cause teh fuel pressure to go outside of what the pressure sensor can even read. I could see it hitting 30K+ PSI with the regulator unhooked and no where for all the fuel to go. Theers always teh chance you have damaged your CP3 by unplugging the regulator with a race valve installed.
 
PAT

PAT

EASY DAY
Aug 21, 2011
1,100
0
0
your back yard
THEFERMANATOR said:
Have you stopped to think that maybe theres a reason the 2 pumps now cannot hold rail pressure? Your stock one quit holding pressure, so you put on a new one that also isn't holding rail pressure. You could have debris caught in the rails from the failed CP3, or you could have a supply problem to the CP3. Don't automatically assume that your old CP3 just died, and a pump swap will fix it. And the regulator works like Tony said. In the absence of voltage to it it goes full open allowing max fuel flow to the CP3. As it adds milliamps to the regulator it pulls the valve open restricting the flow of fuel to the CP3. It does not need full flow of fuel to reach max pressure at idle, ESPESCIALLY not with an oversized pump. And disconnecting the regulator with the pop off blocked could easily cause teh fuel pressure to go outside of what the pressure sensor can even read. I could see it hitting 30K+ PSI with the regulator unhooked and no where for all the fuel to go. Theers always teh chance you have damaged your CP3 by unplugging the regulator with a race valve installed.
Click to expand...

I don't think there would be debris in the lines. The stock cp3 has 175k miles on it and seems to just have worn out. It didn't blow up or anything. Just got tired. So I doubt it created debris.
I've checked the supply lines going to the cp3. I didn't find anything. At least nothing that was obvious.
 
sweetdiesel

sweetdiesel

That's better
Aug 6, 2006
10,390
0
0
52
Thailand
THEFERMANATOR said:
Have you stopped to think that maybe theres a reason the 2 pumps now cannot hold rail pressure? Your stock one quit holding pressure, so you put on a new one that also isn't holding rail pressure. You could have debris caught in the rails from the failed CP3, or you could have a supply problem to the CP3. Don't automatically assume that your old CP3 just died, and a pump swap will fix it. And the regulator works like Tony said. In the absence of voltage to it it goes full open allowing max fuel flow to the CP3. As it adds milliamps to the regulator it pulls the valve open restricting the flow of fuel to the CP3. It does not need full flow of fuel to reach max pressure at idle, ESPESCIALLY not with an oversized pump. And disconnecting the regulator with the pop off blocked could easily cause teh fuel pressure to go outside of what the pressure sensor can even read. I could see it hitting 30K+ PSI with the regulator unhooked and no where for all the fuel to go. Theers always teh chance you have damaged your CP3 by unplugging the regulator with a race valve installed.
Click to expand...

You have good points! However I've ran my lly and lb7 at maxxed rail with 2 cp3s with 3 shims on the lly and welded shut on the 7 and never seen damage
Atleast to the cp3 or any part of the fuel system. Not saying it can't happen or shouldn't be considered but IMHO I dont think it's his issue

These trucks can handle huge press and spikes! I've logged some good ones


Fwiw you can rescale the fuel sensor and read a little higher;)
 
T

TopFueler

New member
Dec 27, 2011
23
0
0
CP3 Rail Presssure

The Fermanator is right!!!
You should never disconect the FCA and run it to WOT. The Rail Pressure Sender reads up to 26,200 psi. Pressure after that is not measureable and has been known to get high enough to break CP3 pumps. If you are looking to run a program that will take you over 26,000psi you should install a higher rated Rail Pressure Sender. The LML reads to 30,000psi and also the Ford 6.7L will read to 30,000psi. If you are running a tune that is asking for 30,000psi and the Rail Pressure Sender only reads 26,000psi the pump keeps pumping higher and higher until it breaks. Because it will never see the rail pressure it is desiring. I have been hearing about the hobb switches that have been installed to cut the signal to the FCA. That all by itself will cause a CP3 pump to fail because it will never stop the pump from raising rail pressure until it breaks. Bosch makes these pumps to run in a specific pressure range. There is always going to be a breaking point. We have been upgrading pump parts to raise the pressure threashold when they will break. As we have been doing these upgrades we see top end parts breaking from even higher pressures than before. Pressures that break through the pumping barrel and also the main pump housing. We have also seen fill valves shoved through the fill valve body. The pressure that it would take to make those parts break like that would be well over 40,000psi.
 
Last edited:
T

TopFueler

New member
Dec 27, 2011
23
0
0
CP3 Pressures

I have also heard of people applying 100-120psi of supply pressure to the inlet of the pump. It was said by a person with the name of Andrew to do this. First of all the front seals will blow out because the cascade valve can not deal with the extra pressure and flow from the excessive supply pressure. This then creates a problem with the return system. The pump can not regulate pressure correctly because it can't get all the extra fuel out of the pump and through the fuel return system. This condition will cause the rail pressure to raise even to the breaking point.
All you need for Dmax supply pressure is 7-8psi with enough flow volume to keep up. Some trucks with big hp have been able to get to 12-14 even with a modded FCA.
All you need for a Cummins supply pressure is 15psi with enough flow volume to keep up.
The CP3 pumps have it's own gear pump that delivers enough pressure to charge the plunger and barrels.
 
Last edited:
T

TopFueler

New member
Dec 27, 2011
23
0
0
CP3 Pressures

I have heard of some tuners that have been doing some creative Rail Pressure Maps. The creativity is about running higher rail pressures.

The CP3 pump is designed to produce what the ECM is asking for. If you ask it to make 30,00psi but it can never see 30,000psi because the pressure sender is maxed out at 26,200psi. The pump will fail from extreme pressure.

If you put a disconect switch in the ECM-FCA wire. You will make the pump deliver more and more pressure until it breaks.

The bypass valve in the rail is suppose to save the system if rail pressure becomes excessive. If the rail is plugged or a race valve is installed and any of the conditions I have explained also happens then you end up with a broken pump.

The only way a stock CP3 pump may survive any of what I have discribed is big injectors and/or big tunning will cause the rail pressure to drop before the pump reaches the breaking point.
We do not modify our FCA's with a Dremill. We use a EDM process and we then do a deburring process.
We test everyone of our CP3 pumps before we ship them.
We have been to Bosch CP3 school and are Bosch Authorized.
Thanks, Brady
 
Last edited:
T

TopFueler

New member
Dec 27, 2011
23
0
0
Extreme Rail Pressure

The higher the rail pressure goes, the higher the heat in the CP3 pump and injection system will go. This is true for higher air pressure as well. The high rail pressures that we all have been seeing has been developing extreme temperatures that could generate 3rd deg. burns if exposed to the CP3 pump at those moments.
The CP3 pump is lubricated and cooled with diesel fuel. When the temperatures go excessive the lubrication qualities diminish of the diesel fuel. The diesel fuels that we all get at the pump today is ultra low sulpher diesel. It already is low in lubricity because of the hydro treating process that the refineries use to make that product.
Bosch has made very well engineered bushing system that the CP3 pump uses. It carries a very high pressure load without failing with low lubricity in diesel fuels of today. Raising the pressures and temperature of the CP3 pump will cause clearances to change and lubricity to fall out.
Back in 2005 we brought to market a CP3.4 pump that was hard to install. We developed a complete kit with a new engine cover for the 5.9L cummins that would accept the bigger pump. The reason we used that pump back then was we knew that that pump being engine oil lubricated would be able to carry a higher rail pressure and still have lubrication and cooling.
Thanks, Brady
 
You must log in or register to reply here.
Top Bottom