2006, XC90 2.5T no start , fuel delivery?

[betoarmenia]

Hi everyone, Thanks for you valuable support and comments. I have got into a lot of trouble with my 2006 XC90, 2.5t. Everything started whit the air mas sensor, dashboard showed Service Engine required, it was driving well but I wanted to fix the light, so ordered the spare part. After some days a new message came "Engine Reduced Performance" but driving was still without a problem, except for a couple of times the car sneezed. I replaced the air mass sensor alongside the spark-plugs, and I was happy with no lights at all in the dashboard. However, my happiness only lasted about 10 minutes. The car suddenly turned off by itself and it was able to crank but didn't start. After trying for several attempts a new message "Immobilizer See Manual". Took me two days reading posts and suggestions, disconnected battery, 5 times lock and unlock and 100 more things, somehow the car started and worked very well for two weeks. then, one Friday afternoon at my job...Again ..

I read more about the flaw and I tried to fix immobilizer problem, blaming the key system. So I bough the antenna ring and replaced, however the car didn't started. (As I was new in this kind of trouble, didn't realized that immobilizer message was not all the time and probably was caused for the attempts starting the car). After the whole weekend doing a lot of things trying to start the car, I disconnected the battery and one big connector in the CEM under the dashboard, cleaned and reconnected and the car started so was able to drive it home.

5 days later one day the car did not start and haven't been able to start it for 3 weeks.

I called a mechanic with a suitable scanner and I could see al the codes generated during all this trouble time. Then when, we erased the codes, and scanned again there is only one code remaining "3f91 Fuel Pump Relay, Short circuit to Supply Voltage".

Now, apparently this car doesn't have fuel pump relay, but it must have a Fuel pump electronic module, (PEM). The problem is haven't been able to find it. I checked in both rear wheels under the liners, close to the fuel filter, over the tank, under the middle raw of seats, pealed everything and no sign of the PEM.

My logic is to find the PEM and replaced before blaming the computer. In case there is nor PEM, there is any place I can send the CEM to get fixed?

I would appreciate a lot your help guys, I am honestly desperate with this car.

Almost forgot, also bought new battery.

cheers

Alberto

[cn90]

I am almost sure it is a bad PEM.
Another location is inside the trunk.

[jimmy57]

There is a fuel pump relay soldered on the CEM circuit board. That car is not assured of having PEM as that is only for markets where evaporative emissions standards are strict. Look at the fuel injector supply manifold (fuel rail) and check if it has the grey and black fuel pressure/temp sensor inserted into end of the fuel manifold There are photos on this site of the location and part. I do not have a photo stored or a car here to take picture from.

[betoarmenia]

Thank you very much Jimmy and Cn90 for your help. Just checked today in the trunk, no PEM.

Also checked the fuel rail and apparently this car doesn’t have the pressure sensor either. Please see some photos attached.

So as far as I understand Jimmy’s explanation, if this car doesn’t have PEM, the problem would be inside the ECM, as the fuel pump relay is builded in. Big question, Can it be fixed or replaced?

Shall I buy the fuel Pump and replace it?

Thanks again

[xHeart]

Your fuel rail:

[cn90]

Thanks jimmy57 for your expertise.

This explains the fact that sometimes I am the junk yard looking for PEM and could not find it in the 2.5T cars!

For cars w/o PEM and FPS, how do they achieve fuel pressure control, is it by the old-schooled fuel relay and vacuum-controlled
fuel regulator (such as in the P80 cars)?

[wanderdüne]

The only other place that I've seen the PEM mounted externally is right next to the fuel filter.
The 2.5T wagons and S60's are sometimes inside of the spare tire well.

[betoarmenia]

Thanks everyone for your comments and help. Apparently the car doesn’t have PEM, nor Fuel pressure sensor. So it looks like the Fuel Pump Relay is included in the ECM. But haven’t been able to find information about Fixing the ECM?

Does anyone know how can I test the Fuel Pump? According to my current situation, that would be the cheapest option atm

Big regards to everyone

Alberto

[wanderdüne]

Here is the Volvo code definition: https://www.dtcdecode.com/Volvo/CEM-3F91

You could test the pump by applying 12V to it. In the link above, Volvo says that the CEM (under the dash likely where the fuel pump relay is) can suffer damage if it is not unplugged when applying the voltage to the pump, so unplug it. I will look on VIDA later today if no-one beats me to it to see if I can find the procedure.

Here is a link to a similar situation to yours:
viewtopic.php?t=66777&start=10

[wanderdüne]

Ok, so not a ton of info on VIDA, but beyond what I had posted, it says in part, that: If the signal cable has been shorted to voltage, there is a risk of failure of an internal ground conductor on one of the circuit boards in the Central Electric Module (CEM). This may lead to the relay for 15-feed on the CEM not working as intended. A result of incorrect function of 15-feed may be that DTC's are set for front seat heaters and for Communication with the Brake Control Module or other possible codes based on the particular vehicle. It also says that the fault symptom is that the battery discharges.

Don't know what the other codes were that you had, but with the battery discharge, it looks like this may be the case. This does not, however, mean that you should not test the pump with 12V with the CEM disconnected; that's certainly the easier scenario. If it turns out to be a short and a problem with the CEM/relay, then that's probably fixable, but more complex.