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2005 fuel pressure question on low side...

Old 05-11-2019, 04:49 PM
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2005 fuel pressure question on low side...

About 2 weeks ago I installed a water seperator and 2 micron fuel filter under the truck. I left the hose off of the tube to cycle the key so I could tell when the filters had filled with diesel fuel. It seemed to take forever and just before checking to see if something was wrong I got fuel to come out but it was not a very impressive stream. I have since installed a test gauge on the low pressure side of the CP3 pump (the line that goes to the bottom of the fuel filter housing). The gauge at idle shows 3 psi. I am assuming I need a new lift pump. I have no after market stuff installed and plan to just install a new in tank lift pump. Is taking that pressure at that location on top of the CP3 pump ok? I know the filter in the housing is also new. Anyone see any issues that did that could have showed poor pressure? Seems to run ok but I do get some chatter from the injectors on accelerating and the injectors are new also.
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Old 05-12-2019, 05:20 PM
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Thanks for the replies!!!
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Old 05-12-2019, 05:50 PM
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Sarcasm is neither warranted, justified or needed here. In any case it is the weekend, special day too, so perhaps not many folks are logged in. Your sarcasm may have precluded any replies.
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Old 05-12-2019, 07:09 PM
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I don't need a lecture. If you have nothing useful to contribute then don't reply. I realize what today is. I posted this yesterday. What are YOU doing here today???
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Old 05-12-2019, 07:18 PM
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Pretty demanding for someone looking for help......Ben
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Old 05-13-2019, 10:22 AM
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Originally Posted by Deanp88 View Post
About 2 weeks ago I installed a water seperator and 2 micron fuel filter under the truck. I left the hose off of the tube to cycle the key so I could tell when the filters had filled with diesel fuel. It seemed to take forever and just before checking to see if something was wrong I got fuel to come out but it was not a very impressive stream. I have since installed a test gauge on the low pressure side of the CP3 pump (the line that goes to the bottom of the fuel filter housing). The gauge at idle shows 3 psi. I am assuming I need a new lift pump. I have no after market stuff installed and plan to just install a new in tank lift pump. Is taking that pressure at that location on top of the CP3 pump ok? I know the filter in the housing is also new. Anyone see any issues that did that could have showed poor pressure? Seems to run ok but I do get some chatter from the injectors on accelerating and the injectors are new also.

IMO, 3PSI at idle with a factory in-tank lift pump is low. This means that it is likely going to 0PSI under heavy throttle/heavy load conditions.
You do have your fuel pressure gauge installed in the correct location. (Monitoring the input of the CP3).

Typically the factory in-tanks fuel pumps run at 5-7PSI at idle and drop to 3-4PSI under load.
Just to compare.. My 2004.5 truck with an aftermarket external fuel pump runs at 13-14PSI at idle and about 10PSI at heavy load/heavy throttle.
It's been this way for over 13 years. I'm monitoring the input to the CP3 and I have 3 fuel filters.

The 1st step I recommend is to remove the fuel tank canister and inspect the bottom inlet screen/grid for blockage.


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Old 05-13-2019, 03:23 PM
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I appreciate the information. I did notice that yesterday when I pulled in I checked the pressure and it was at 0. The tank is coming down tonight...
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Old 05-13-2019, 07:42 PM
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I'm pushing fuel with the stock in-tank pump through three filters. I know I'm on borrowed time. A FASS setup is in the near future.
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Old 05-14-2019, 02:50 AM
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Originally Posted by Danderson View Post
I'm pushing fuel with the stock in-tank pump through three filters. I know I'm on borrowed time. A FASS setup is in the near future.
I'm glad you mentioned that. I am doing the same thing. I already ordered a replacement stock pump which will be here today. I am needing the truck this weekend. I did not consider an aftermarket pump because they seem to all come with the filters. I did look at the Fleece in tank pump but $700 seems steep for another in tank pump. I suppose in the future I will need to plan on a aftermarket pump to keep pressures up. I do not intend to add anymore power, other than a Smarty Jr which I have now. Any suggestions on a pump that does not come with filters? Do the extra 2 micron filters and water seperators really add that much restriction?
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Old 05-14-2019, 08:57 AM
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Originally Posted by Deanp88 View Post
I'm glad you mentioned that. I am doing the same thing. I already ordered a replacement stock pump which will be here today. I am needing the truck this weekend. I did not consider an aftermarket pump because they seem to all come with the filters. I did look at the Fleece in tank pump but $700 seems steep for another in tank pump. I suppose in the future I will need to plan on a aftermarket pump to keep pressures up. I do not intend to add anymore power, other than a Smarty Jr which I have now. Any suggestions on a pump that does not come with filters? Do the extra 2 micron filters and water separators really add that much restriction?
Yeah,I looked for a frame mounted, stand alone pump too. No dice but maybe someone has one. Until the filters get dirty I guess the restriction is not that bad.
The Fleece does look good but no reviews yet. The stocker though was designed to push through one filter so it's gotta be working harder.
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Old 05-14-2019, 10:34 AM
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Originally Posted by Danderson View Post
Yeah,I looked for a frame mounted, stand alone pump too. No dice but maybe someone has one.
I had a stand alone, frame mounted fuel pump on my '03. I used a Walbro 392 which puts out too much pressure but I also installed a pressure relief valve which sent excess flow back to the tank thus limiting the pressure to the CP3. Full-Race has the pump (if you tell them FMB sent you, they'll say "who?"), I didn't look for a PRV but I'm sure they are out there. Summitracing also carries the pump and related mounting hardware.

If my rememberer isn't too broken, I think DTR used to sell the kits that had the pump, mounting hardware, PRV, wires, etc..
Back to morning brew . . .
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Old 05-14-2019, 07:43 PM
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Well new pump is in and all is well. I will put a frame mounted pump on my list for future purchases. I appreciate the help. One question, when checking lift pump pressure at the CP3 pump, there are 2 lines on the top. One towards the front of the truck and one towards the back. Which banjo bolt are you guys checking from?
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Old 05-15-2019, 01:13 PM
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Originally Posted by Deanp88 View Post
Well new pump is in and all is well. I will put a frame mounted pump on my list for future purchases. I appreciate the help. One question, when checking lift pump pressure at the CP3 pump, there are 2 lines on the top. One towards the front of the truck and one towards the back. Which banjo bolt are you guys checking from?

"All is well' ?!! How about a PSI measurement?


There are tons of guys running the stock in-tank pump thru various aftermarket fuel filters and water separators with no issues.
Installing an external aftermarket fuel pump with the stock in-tank fuel pump and fuel canister is not so simple. I will let you research that.

As I mentioned , the best place to measure low side fuel pressure on a 5.9L Common rail is between the last fuel filter and the CP3 itself.
This way you can tell if one of the filters is plugged or restricted.

You should never mount any gauge or sender directly to the Cummins engine. The Cummins engine vibrations will destroy the sender. Ask me how I know...
I recommend to toss the metal fuel inlet to the CP3 and go to high quality 3/8" rubber hose. Then mount a T-fitting for the fuel pressure sensor.
The stock metal line goes from the bottom of the fuel filter canister to the CP3.

Glacier Diesel performance is an excellent shop in Spokane Washington that has tons for Cummins fuel system parts.

https://www.glacierdieselpower.com/i...ef=category:85

https://www.glacierdieselpower.com/i...ef=category:35

I have had the pricey Autometer stepper gauge fuel pressure gauge installed for over 12 years. It's still about US$250 and worth it IMO.
I have the sensor mounted in the T- adapter as above in the 3/8" rubber fuel line between the last fuel filter and the CP3.
This will isolate the fuel pressure sensor from the engine vibrations.
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Old 05-15-2019, 03:48 PM
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Thanks. The pump I installed is a Delphi pump for my truck. The PSI when I turned it on was 20-25 PSI. I thought this was high for a stock pump so I had a friend who is a mechanic check which pump Delphi makes for my truck and he came up with the same pump number. As for the gauge, I do have it attached where you stated at the CP3 pump and I used a replacement banjo bolt fitting from Geno's garage that I attached a hose with parker fittings and then a liquid filled gauge. The hose is about 30" long.
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