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Discussion Starter #1
i took my truck to the dealership yesterday for a p0190 DTC and they replaced the fuel pressure regulator, when they they got finished the truck then shot this p0087 dtc??? now they are saying it might be a sensor located below the intake and they are going to have to tear the motor down to check it. anyone had this code before and know what was done to resolve it.
 

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P0087 - Fuel Rail Pressure Too Low

Sounds like they mis-diagnosed the first time. I can't even find a description for a P0190 code.
 

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There are many things that can trigger the P0087 code. One is restricted fuel filter, fuel lines or gell in the lines. Also early trucks had a problem with the rubber fuel hoses at the driver side valve cover, and below the drivers feet area. The lines get kinked, or collapse. Usually more so when it it hot out, and pulling heavy load.
 

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P0087 - Fuel Rail Pressure Too Low

Sounds like they mis-diagnosed the first time. I can't even find a description for a P0190 code.
p0190 is fuel rail pressure sensor
 

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There are many things that can trigger the P0087 code. One is restricted fuel filter, fuel lines or gell in the lines. Also early trucks had a problem with the rubber fuel hoses at the driver side valve cover, and below the drivers feet area. The lines get kinked, or collapse. Usually more so when it it hot out, and pulling heavy load.
this trucks only got 33000 miles on it and ran perfectly, dealership said as soon as they changed the fuel rail pressure sensor the p0087 came on. they just called and said they have another dmax same year as mine with the same code they have been working on for 3 days.
 

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Finally solved this code. One of the sensors under the intake had fine medal shavings in it (probably casting mold left after initial flush). Gm told my dealership tech to put on a new injector pump, all new fuel line, and all new injectors. Thankfully its covered under warranty, would hate to see that repair bill.
 

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Nice to be under warranty, I asked about my warranty and GM dealer laughed. Ha! 110,000 miles and over 8 years old.
A few weeks back, my truck starting sending messages about replacing the fuel filter, so I ordered a FASS fuel system. It started to act like it is running out of fuel, so after a small incline or minor pull the engine would slow until enough fuel pressure builds back up. I thought for sure the FASS system would solve the problem.
I installed the FASS system and I clean/checked everything. I removed the tank and ensured that the pick system was not plugged. I installed FASS sump system. I did not find any problems with the fuel lines and tank. I install the FASS filter delete system at the original fuel conditioning module, which had no obvious problems. I reconnect everything and ensured that there was no leaks with a positive pressure at the fuel pressure/vacuum test port.
I reset the fuel filter life and started the truck. The same problem, the truck was running out of fuel after a minor pull. The engine light came on. I hooked up the scan tool and got P0087. I looked at the engine data on the scanned tool, the FPR2 (fuel pressure regulator valve on the fuel rail) was first to loose pressure, then the rail pressure would drop, and at the end the FPR1 would reduce. Based on this and some of my research at this forum I got concerned that maybe it is the CP4 pump failing.
First I removed the FRP2 (fuel pressure regulator valve) at the fuel rail and inspected it. No abnormal conditions, the valve was clean with no metal debris. Next i removed the FPR 1 (inlet metering valve) and inspected it. Again no abnormal conditions.
I order a new Exergy Inlet Metering Valve E05 10505 and I will reassemble everything, but what could be the problem? I know I am getting fuel to the CP4 pump via FASS.
Any help will be appreciated.
Thank you, g
 

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gdayzie did you ever get this figured out? i am having the same issue.
 

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Any luck figuring out this issue gdayzie / Bryan Hopper?

I'm having a similar issue and here is what I did so far...

  • Installed an AirDog II 165-4g
  • Replaced the fuel sending unit with a new OEM unit
  • Replaced the CP4 pump
  • Installed a Rudy's fuel filter delete
  • Installed a GlowShift fuel pressure gauge with the sensor installed in the fuel filter housing where the bleeder screw was
  • Installed a Edge Insight CTS2 to monitor Fuel Rail Pressure

The actual situation is that if I push the pedal slowly, FRP goes up as DFRP... If I go from idle (or close to it) to wot I get close to 30K on DFRP and close to 10K on FRP...

When I first installed my Airdog and the filter delete it would not prime fuel with the pressure setting that the airdog came set at. So I ordered the gauge and I had to set at 14psi, so it get to 3psi at wot. I've tried setting at 10-12 psi but it would go to 0 psi wot and throw the P0087 code and/or "replace fuel filter" DIC...

Sometimes when I start the truck the pressure gauge reads 20 - 25 psi. I'm not sure why, but it just seems to high comparing to what everybody runs at and it seems like it would be relevant to the topic...

Somehow it looks to me like the airdog is not putting enough fuel out... (good pressure but low flow/gpm)

I've ordered a new Fuel Pressure Relief Valve as it seems to me like this would cause the low fuel pressure in the rails, as the pressure in the Low Pressure system is not going to 0 psi...

I've made a video to help illustrate how the truck is behaving:

Any inputs from the ones that had similar issues are appreciated... Thanks in advance guys!
 

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I was installing a receiver hitch on mine and had to remove the fuel tank guard. After removal i noticed that the fuel tank guard was rock solid. Removed it and it was packed with around 50-70 pounds of dirt. The fuel tank was pushed in almost to the top of the tank. also installed a Fass fuel pump on it as well and all seems to be good. My guess with my problem was the dirt had pushed the pickup tube to a kinked position. I need to replace my fuel sender now as it is acting up after dirt removal from fuel tank shield. Gonna do that later when I have time. Also found later was a loose fuel line. I think there was multiple issues with my fueling problem. I also replaced both fuel solenoids one on the pump and one on the fuel rail. Happens when you get a truck and not know the history of a truck.
 

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Thanks Brian! I will check the fuel tank and the guard to make sure that I don’t have a similar situation. It doesn’t look like but it’s worth checking...

The solenoid that goes on the rail is getting here on Thursday and I’ll get it replaced.

I’m also going to do a bucket test with my lift pump. I curious to see how fast it’s going to fill up a 5 gallon bucket and then I’ll check how long it takes to get the 5 gallons of fuel back to the tank...
 

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Today's updates...


got the fuel supply line off and let it drop into a bucket and noticed that the flow was not consistent. It was pretty good as soon as I turned the ignition on but it would get erratic and looks like air coming out right after. After almost 2 minutes I had approximately 2 gallons in the bucket and the pump was supposed to deliver 5 gallons in 109 seconds (converted from the nominal 165 gph that the lift pumps has)...

As a next step I unhooked the fuel supply line for the Airdog from the tank and put inside a bucket filled with diesel and it ran much more consistent that way, with no foaming or air coming out... at that point I decided to drop the tank:

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I was hoping that I would find a lot of stuff inside the tank causing a clog or a kinked hose in the fuel sending unit but I didn't... everything looks good:

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So, I came up with a theory that the problem is that the fuel is not getting in that basket as quick as the airdog draws fuel out of it and in that situation I get the lower FRP. Lower fuel pressure is happening when I have less than 1/2 tank and I go from cruising to wot all of a sudden... If I keep mid acceleration the truck is very responsive and goes all the way to 20-29 Kpsi FPR matching the Desired FRP with no issues at all...

I'm wondering if I could modify the return from the airdog system to get into the basket or if I need to install a sump...

I'll probably get rid of that diesel and put new/clean diesel in and fill the tank to see how the truck is going to behave... FPRV gets here tomorrow and I might install it just to be on the safe side and go for a trip over the weekend (wish me luck! lol) ...
 
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