2003 Fuel Pressures

[RSnaith]

Originally posted by AndyMan

I definately don't want to risk putting you at odds with another shop, but question the single pump statement... SO, why would adding a pusher pump to my existing set up be a bad thing? Gimmie some suggestions bud!!! What can I do to keep my starving my precious CP3?

Well it may put us at odds, but we're all gentlemen here and can recognize that each vendor has developed a solution that may indeed solve the problem.



We like single pump rigs for a variety of reasons:



1) Simplicity. 1 pump, no external bypasses or additional filters. Less to go wrong, easier to hook up.



2) When pressure starts to drop, you know where the culprit is. In dual pump settings, you've got two different sources of problems. Tack in regulators, bypasses, and additional filters and you've just added more things that can wrong.



3) Utility of the truck. I have by no means seen all the pusher pump assemblies on the market, however many of the ones I've seen end up sticking below the frame rail, or stuff the pump out in an open area. For those of who do drive off-road, this is bad news. Snow, stumps, rocks and little animals can all get to that pump assembly back there. We replace between 2 and 5 pusher assemblies a month around here because the rear mounted lift pump has gotten eaten out from rain or salt water impregnation. Probably not an issue if you live in a dry climate, but definitely bad news for those of who are snowbound 5 months of the year, or who have alot of rainfall.



4) A single pump is perfectly capable of pulling fuel that short distance, and indeed, the siphon effect from the tank is probably more than what the engine is even asking for. We haven't measured the siphon effect from an 03 yet, but on an 02, the siphon effect would drain a fuel tank in less than 15 minutes. Thats 120 GPH of siphon. On the 02 and unders, the only problem in the system was those restrictive lines after the lift anyway, so thats all you needed to address. On the 03, it appears to be a volume problem and a line problem.



5) Dual pump systems tend to be too high pressure. I know this is debatable, but we've seen VP44s that have failed due to excessive inlet pressure (our opinion verified by an indepedent pump shop). We don't know what the CP3 needs for inlet pressure, and can't find that information anywhere, but we feel there is a reason its set to 11. 5 PSI from the factory. So, if we can deliver all the volume that the CP3 wants, at stock pressure levels whether you are idling or at WOT, then I'd say we've got the problem nix'ed.



Our take on the situation is that we need a good single pump system, mounted under the hood again to keep it protected, and using lines that the pump was designed to use. The FASS system looks sweet, as we won't need to worry about a custom machined fitting to mount on the fuel filter canister. But it is awful high pressure. Maybe an external regulator would work on it, but the system wasn't designed to be used with one. We're looking into that critter, as well as other heavy duty pumps from other manufacturers. Its going to be awhile. The 02 fuel systems taught us a bunch, but we've got some unknowns here that we need to play with.

 

[AndyMan]

More outstanding Info!

Thanks again... I'm really learning here. It stinks we don't have the answers yet (even though dc and cummins should have provided them from the factory), but it sounds like you are treating this as a top priority. That's excellent!!!



You're the man! Keep it up!

Andy

 

[Joseph Donnelly]

I'm running the Diesel Dynamics fuel pressure gauge (Auto Meter) and their lift pump kit. The fuel pressure setup sends diesel fuel to an "isolator" diaphragm. 50/50 antifreeze/water goes from the other side of the diaphragm to the gauge. I wouldn't run diesel fuel into the cab for safety reasons. If you want to test your fuel pressure without mounting a permanenmt gauge, get one of the Schrader valve equipped banjo bolts and adapt it to take the plastic line/compression fitting like is used for boost gauges and oil pressure gauges. (DD has such an adapter. ) You can then use a windshield wiper blade to hold the gauge down while you do a brief test drive.



The capacity of the stock Gen3 lift pump must not be too great. I found it easy to suck the pressure from 9 to 0 under power. I am now runing the DD pump kit and recommend it as one appropriate solution to the lift pump problem. I like it not only for the extra volume and pressure, but for its clean and easy installation. Be sure to check your stock pump pressure, especially if you have increased the power of the engine.

 

[Vaughn MacKenzie]

On my last truck I ran a mechanical FP gauge with a direct fuel line into the cab. The only concern IMO is the mess it would create if it leaked, I don't see how it could be a safety hazard, except I guess in the event of an accident causing leaking fuel in the cab wound increase the danger to a trapped occupant if the vehicle caught fire.



What I did was use a standard Autometer gauge, rethreaded it for 1/8" NPT and ran the standard small-bore nylon tube that is used for boost gauges to the fitting below the filter canister. It worked awesome and didn't have any of the maladies so many experienced with their gauges. Cost me $35.



Rod I was hoping when I bought my '03 I wouldn't have to do much fuel system BOMBing, after going overboard with the '01. Now I see that's wishful thinking! I'm tentatively planning on doing Aeroquip fittings and locate a PE or similar fuel pump back near the tank. I'm hoping that would suffice for my Bully Box but may not for anything above that. I don't want to invest in a full 1/2" system but maybe I should jump straight to that. So far I've haven't experienced any stuble, hiccup or miss after a hard blast, the only thing is very slight rough idle sometimes which goes away with a blip of the throttle.



Vaughn

 

[RSnaith]

Originally posted by Vaughn MacKenzie

The only concern IMO is the mess it would create if it leaked, I don't see how it could be a safety hazard, except I guess in the event of an accident causing leaking fuel in the cab wound increase the danger to a trapped occupant if the vehicle caught fire.

Diesel does indeed make a mess inside a cabin, and at one time, we firmly believed that an isolator was definitely the way to go. We worked with a gauge supplier to develop a good solution, and after 1 1/2 yrs, it still wasn't a reality. During this testing time, we did have several isolators fail, which then passed diesel into the cabin anyway. Also during this testing, we had the fittings on the gauge fail, which sprayed antifreeze and water all over the inside of my truck. If you think diesel is a mess to clean up, give antifreeze a shot. When I sold my 01, I could still smell it on a warm day, and on the part of my dash where the antifreeze was, dust would collect, no matter what I used to clean it.

 

[AndyMan]

Confused

ok. I have managed to toally confuse myself, and I still refuse to let this thread die. From the service manual, I see that the only truly low-pressure pump in our fuel system is the "Fuel Transfer (lift) Pump" that is attached to the fuel/water separator assembley. Natually, I have a couple of questions...



1. )Am I correct in saying that a pusher pump would work in conjunction with the lift pump?



If I tried to go the one pump route:



2. )If I were to add say... a PE4100 that would regulate pressure at between 11 and 15psi, would I remove the lift pump? or simmply just unplug the power wire to it? or what?



The lift pump has check valves to prevent fuel bleedback during engine shutdown, so I don't think that removing it is an option. However, if another pump is in place that is regulating the fuel flow to the filter/separator, then the regular operation of the lift pump is not neccessary. If the answer is simply to unplug power to the lift pump, would the ecm go berzerk since it controls the lift pump? What about priming? Without the lift pump, what would be in place to perform that duty? Would the PE4100 be able to do that?



I'm sure I've blown this all out of proportion. Please straighten me out on this.



Thanks,

Andy

 

[KLockliear]

Originally posted by Jeff_K

Also, I had my truck dynoed at a local shop with the EZ on the 60hp setting and with my 5" exhaust and got 339hp (torque was not reading right). After I installed the DD pusher pump kit and the DD airbox, I set the EZ to the 80hp setting and had it dynoed at the same shop a month later at 434hp

Jeff

Jeff, I assume that's a typo? Maybe 344hp?



Andy, I would suggest that you start with a gauge and determine first that you need a pusher kit. I'm all for "KISS" Keep It Simple Stupid, or bang-for-the-buck, so don't fix what ain't broke. Like Rod, we went through teething pains with the mechanical isolators until we found what we run now. Very reliable and easy to setup piece with the stuff we supply.



IF you need the pusher kit, our kit includes the pump, lines and fittings to go from our pump out back, to the stock pump location (where the stock pump is removed), and fittings and lines from the filter to the CP3 pump. It's a complete kit offering. With the volume and pressure our kit makes, the stock pump was a restriction. Removing it offered more pressure and volume to the CP3, which is why we had the special adapter made to dispose of the stock lift pump.



Hope that helps.

 

[AndyMan]

Keith,



Your point is well taken. Thanks so much for your response.



On a sort of different note... You mentioned your gauges and isolator kit (or lack thereof). Do you have a 0-15 or 0-35psi fp gauge that is white faced with a black bezel? I couldn't find one on AutoMeters site, but I know they will custom make just about anything if you're willing to pay. Can you elaborate on the fp gauge setup you all offer? Maybe pm me with a price. If you can't pm it, my e-mail addy is -- email address removed --.



Thanks again,

Andy

 

[KLockliear]

Yes, they build two gauges for us. Black face, black bezel and white face, black bezel, 0-35psi.



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or



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Pricing is listed on our "orderform" page on the website. The gauges are listed as:



DFPG - B/W 1/2. (Dodge Fuel Pressure Gage Kit - Black or White face, 1 or 2) 1 and 2 denote the fuel lines.



1 is for use with the stock lines/banjo fitting, 2 denotes use of our big fuel line kit. Andy, your truck with stock fuel lines would get a DFPG-W1. That is listed on the website page.

 

[berg]

Ya and my dealer told me the same thing for my 02 I think its just a way to cure the problem for them!! not me!!! but it will be cheaper for em!!

Originally posted by TDRadmin

Hello Members! In the for-what-it-is-worth department, we've noted some fuel pressure specifications that are correct, but they are also incorrect. Here is the story.



In a conversation with some of the tech guys at Cummins, we've verified that the fuel pressure specification that was published in the 2003 Chrysler Service Manual is erroneous. Changes have been made to correct the Chrysler Service Manual to remove all mention of lift pump pressures. Hotline personnel are aware that they should not troubleshoot this system based on lift pump pressure. There is not a fuel pressure specification for the new 2003 lift pump. The only specifications that are critical are flow specifications for this system. The minimum flow from the fuel lift pump is 38 ml per second (using Miller tool #9014) with a max fuel inlet restriction of 6 inhg (using Miller tool #6631 and a vacuum gauge).



I'll continue my discussion as to the "cooling" role that fuel plays in this new high-pressure, common-rail fuel system. I'll advise once I have more information.



Robin

TDR Admin

 

[lmills]

Are these Carter pusher pumps the same that were used as pusher pumps fop the 24- V VP-44 engines?

 

[DLeno]

what I find fascinating about this new found religion of DC (not to use fuel pressure as a spec) is that all they did was to express the performance of the low pressure fuel system in figures that that most of us can't measure directly. Everything they did, and all the performance criteria they published, can be expressed just as accurately in terms of pressure. they just made it hard on us because they wanted to.

 

[Yo Hoot]

Here are some cutaway pics of the high pressure pump...



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This is the integral gear rotor lift pump...



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Th fuel filter assy... .



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[KLockliear]

Originally posted by lmills

Are these Carter pusher pumps the same that were used as pusher pumps fop the 24- V VP-44 engines?

The one we use in our DPPK02 kit for the 03+ trucks is NOT the same as the DPPK01 kit for the 98. 5-2002 trucks.

 

[Yo Hoot]

The Duramax has the same CP3 pump. It doesn't use a lift pump at all. It just SUCKS

 

[KLockliear]

Yo, the guys making decent power with them (over 450rwhp) are adding pusher pumps though.

 

[CoastyAV8R]

From what I have read in various magazines and articles, the only reason they have a lift pump on the new HPCR motor is for convience while changing the fuel filter so you don't have to maunually pump fuel into the fuel filter housing. The duramax doesn't have one and the owners have to manually prime the fuel filter housing when changing a filter or if they run out of fuel. I'm confused because what I read was written by smart diesel guys, but now I see here on TDR some pretty diesel guys discussing the need to monitor fuel pressure. So what the heck? Who is right? So does a stock truck need to worry about fuel pressures?

 

[Yo Hoot]

KLockliear is right on the high hp trucks they found fuel supply was beginning to starve so they tried adding lift pumps.



I think it's still in the experimental stage. I'm not sure if they have proved any gains .

 

[KLockliear]

I know that some have seen gains... in performance, as well as the ability of the rail pressure to stay more constant.

 

[SClements]

Originally posted by CoastyAV8R

From what I have read in various magazines and articles, the only reason they have a lift pump on the new HPCR motor is for convience while changing the fuel filter so you don't have to maunually pump fuel into the fuel filter housing. The duramax doesn't have one and the owners have to manually prime the fuel filter housing when changing a filter or if they run out of fuel.

I think that's right, but at higher hp levels these trucks suck more fuel than the lift pump can provide, so a pusher pump is necessary to provide more volume so the pressure pump isn't starved for fuel.

Seane