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Discussion Starter · #1 ·
Loosing fuel pressure. Throwing code for fuel pressure 0089. Have replaced - Fuel pump, fuel filter, fuel pressure sensor (twice), Fuel Control Module and still issue.... will start out at 300 kPa... then down the road will start to drop... won't be able to "go into passing gear... will hit 3k RPM and shudder. then eventually will keep going down in pressure... 200 . then to 100 . then 50's . then to 0... will pull over. stop for a minute. Turn key back on and start and will be back to 300. and then start process all over again. Car has been great to me. bought new and has 289K. but can't keep sinking money into, so any thought would help before I need to scrap it.
 

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Discussion Starter · #4 ·
at times after clearing I have had I believe 0087 and another which was too lean? maybe 0094 I swapped the relay for the fuel pump. I cleaned any grounds. I am at a total loss.
 

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You need to be able to monitor voltage or duty cycle to the pump. If the pump is told to stop making fuel pressure thats one thing. If your signals are good, then you likely have a delivery issue. The lean code makes sense if its running out of fuel.
 

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With a simple volt meter you can monitor voltage while driving. You could set it up and use your phone to record it, or just have someone else drive the car while you watch it. You just want to make sure the pump isn't losing signal.
 

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Discussion Starter · #8 ·
what can cause the fuel pump or pumps to stop making fuel pressure? What controls that system? Is there a recirculating valve that opens to return fuel to the tank? Could that be faulty? I need more information on how the fuel system works. What components are in it that control it. There is only one fuel line into the rail then the injectors and the fuel pressure sensor... where is the return line?
 

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There is no return line its an on demand pump. Its controlled by the Fuel pump control module (located either on the side of the fuel tank - if its original) or possibly relocated to the trunk area where the spare tire is located. You can take the cover off the PEM (fuel pump control module) and see if its all corroded if it is, replace it. You can swipe one out of a junkyard if it has the correct part #.

Per Volvo/Vida

Fuel pressure regulation, diagnostics


General
The fuel pump control module has no functions for diagnostics. Fuel pressure regulation components and functions are diagnosed by the engine control module (ECM).


The following components/functions are diagnosed by the engine control module (ECM). Diagnostic trouble codes (DTCs) can be stored for each component/function:

Fuel pump control module, the power supply is checked. A diagnostic trouble code (DTC) will be stored and the fuel pump will not work if there is no power supply to the fuel pump control module

Fuel pressure sensor with temperature sensor, the pressure and temperature signals are checked to see if they are outside the normal operating range of the sensor. If a fault in the fuel pressure sensor is detected, the fuel pump (FP) will run at full power and the pressure is governed by the by-pass valve in the fuel tank

Fuel pressure, the engine control module (ECM) compares the requested pressure with the measured pressure(the signal from the fuel pressure sensor). If the measured pressure deviates excessively from the requested pressure, or if the pressure pulses, a diagnostic trouble code (DTC) will be stored for incorrect fuel pressure. The diagnostic is not active if a diagnostic trouble code (DTC) for the fuel pressure sensor is stored. A diagnostic trouble code (DTC) for fuel pressure will be stored if there is a fault in the fuel pump

Communication cable.The engine cannot be started if there is a fault in the communication cable between the engine control module (ECM) and the fuel pump control module. A diagnostic trouble code (DTC) will be stored for the fault.

For further information about diagnostic trouble codes (DTCs), see Information, diagnostic trouble codes (DTCs) in VIDA.


Components/functions which cannot be diagnosed:
If there is a fault in the by-pass valve in the tank unit, the starting process of the engine will take longer if the valve is leaking fuel when the fuel pump is off. If the valve does note open when there are pressure peaks in the fuel system, engine operation will be negatively effected, especially after engine braking.
 

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Discussion Starter · #10 ·
So originally, the FCM went bad. Taken to a friends repair shop who "jumped" it so it could run. I then bought a used one on ebay but it was the wrong one (one for the metal tank, I have a plastic tank). It worked but threw a code. No driving issues but needed car inspection renewed and can't with a check engine light on. Ordered brand new FCM from Volvo and had it swapped. Code cleared but fuel pressure issue (would not go over 3500 RMP like when trying to go into passing gear. repair shop put in new Fuel pressure sensor and new fuel pump. still issues. So that is where it is at. I have even swapped back to the other FCM but no change and same issues.
 

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Well if its running out of fuel, the next step is to monitor pump voltage while vehicle is running. That would be my next step.

Was a new bosch pump installed? I've never had to warranty one unless it leaked (cracked sender nipple)

A good technician is always a little "paranoid" - Even if the part was new/recently replaced you have to suspect everything and double/triple check sometimes.

If you would like to chat over the phone some, PM me and I'll give you our shop # :)
 
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