Problem with a 2006 GMC 3500 duramax. Under heavy loads the check eng light comes on and code reads low fuel rail pressure. Just had a new pump installed and fuel filter and fuel bypas valve. HELP

chevy 1500 or 2500 or 3500
what engine size .(gas) 6.6Liter????Diesel it is. (
P0087
DTC P0087: Fuel Rail Pressure (FRP) Too Low
The actual FRP is less than 22.5 MPa (3,263 psi).
line above pasted from SM
gasoline put into fuel tank (step 1 in the diag page i pasted here

• When ambient temperatures are below 0°C (32°F), the fuel tank pickup screen may be iced over from water in the fuel tank.
• When power enhancing devices have been attached to the fuel rail pressure sensor circuits, this DTC may set and adversely effect the fuel system components. (means hack/mods done)
• If the fuel pressure valve is not torqued correctly, the valve will leak fuel into the fuel return system causing this DTC to set. The fuel pressure relief valve uses a bite type seal, and proper torque is essential for valve to rail sealing. Refer to Fastener Tightening Specifications.
• A sticking FRP regulator may cause this DTC to set.
• High fuel injector return flow may cause this DTC to set.
• The addition of fuel system enhancements, such as auxiliary fuel tanks or add on fuel filters may relate to driveability complaints.

putting additives in to the fuel tank?

2006 5.9L dodge mega cab 3500. (TURBO DIESEL)_? RAM 35500
did all that and failed to scan he PCM,(USA car) OBD2 spec.here.
why skip step 1?
Shops (most) fail to find problems that are gone as delivered.
most never drive it, at all, nor scan and drive. it. seems yours tired.
learn that to find intermittent problem we scan and drive.
if need be we use remote pressure gauge to see pressures fall.
is the fuel old and bad, not a full time DD, daily driver, and old fuel.?
new CP3 diesel fuel pump. at $600+ ouch,
what about fuel filters.?
fuel injection pressure regulator bad or fuel pressure sensor.
intermittent COMMON RAIL INJECTOR? (hard to test nor easy cleaned)
the fuel rail pressure can be monitored, if it drops you know why
injection pressure regulator,.as CP3 is new.
what about the lift pump , problems
"The fuel transfer (lift) pump is self-priming.
lift pump must feed the
The fuel injection pump supplies extremely high fuel pressure to each individual injector through the high-pressure lines."
3 filters, and this
The fuel filter/water separator assembly is located on left side of engine above the starter motor. The assembly also includes the fuel heater, Water-In-Fuel (WIF) sensor and a screened banjo bolt attached at the bottom of the fuel filter canister.
what happens if the WIT, water in fuel sensor trips
does ECU cut fuel? or what.? IDK but is one more part to fail
of many.
I guess this newer truck, OBD2 does not do misfire of injectors tests.?
codes that warn of weak cylinders. ?
Vin Code C, engine,.
best is drive the truck and scan log all DTCs
there are even fuel pressure warnings, DTC>

short example of some. SCAN at the fail live, is best.

Trouble Code: P0088 (5.9L L6 VIN C Auto)
FUEL RAIL PRESSURE SIGNAL IS ABOVE MAX LIMIT

Trouble Code: P0107 (5.9L L6 VIN C Auto)
MANIFOLD ABSOLUTEPRESSURE SENSOR CIRCUIT LOW

Trouble Code: P0148 (5.9L L6 VIN C Auto)
HIGH PRESSURE COMMON RAIL\\

Trouble Code: P0191 (5.9L L6 VIN C Auto)
FUEL RAIL PRESSURE SENSOR PERFORMANCE

and P0192 too low PSI
i stop here lots more in the SM

Not real familiar with your engine, but generally you have two coolant temp sensors. One just runs the dash gauge. the other speaks to the computer and acts sort of like a choke. If the computer thinks the engine temp is hotter or cooler than it actually is, fuel metering will be wrong. The more likely culprit is the low fuel pressure. I have even seen a bad fuel cap cause something like this, as these systems operate under pressure I believe.

P0087 GMC - Fuel Rail Pressure Malfunction Pressure Too Low

Possible causes - Faulty fuel pump
- Blocked fuel filter
- Faulty fuel pressure sensor
- Fuel pressure sensor harness is open or shorted
- Fuel pressure sensor electrical circuit poor connection
- Faulty Fuel injector

Do you have an after market programmer installed .what code is it showing .

Fuel pump relay is in cavity A in the rear SAM ( Signal Acquisition Module.) on the left hand side of the trunk behind a door.

When did you check the voltage..... you must read it while cranking or you will get a zero voltage reading.. The low pressure tank pump builds pressure to the high pressure pump and then shuts down until a pressure drop is sensed in the low pressure line and it then starts up again.

If rail pressure is too low, it often is the high pressure pump in the engine or the relief valve in the fuel rail. The tank pump is low pressure just to stop the tandem pump from cavitating by sucking too hard.

Mercedes can check the rail pressure and do an injector pressure drop to rule out a leaking injector.

If the tank pump is bad it will require replacement.

Have you serviced the fuel filter/water/seperator/heater? P0093 could also refer to the possibility you filled the truck up with fuel when it was running setting that code. The code for fuel pressure is derived at the rail delivery on a Duramax, again check the fuel filter, or there is a obvious leak somewhere. Hard to tell without looking at it, but start there. Is fuel cap sealing, look at O ring in cap make sure it is not degraded or missing. Other than that could be pump (delivery) for fuel, costly. Look for wetness from the tank, lines, pump, etc...

I had the same problem it turned out to be the injector pump witch gm covered it.

This is the problem with the sensor you need to get it checked with the dealer as this is the common problem with these trucks as these keeping coming ......................................




Good luck................