Free-PPV
By the way, what happened to your car?
Could you figure out what the culprit was?

 

I had gone through everything, just as you have, bought a smart phone app which works with the many diagnostic readers so I could monitor fuel pressure while driving, which confirmed my fuel pressure would drop to near zero when engine died, so I knew what problem was, but it was not easy to fix having gone through everything and replacing everything related to engine dying and stalling and once, would not start again.

I pulled CEM and found that water indeed got into box due to clogged drains in cowl area, again mine is an Xc90, so I assume similar to other models. Once I saw that, my heart sunk knowing how many people had same issue and how it destroyed their CEM. Being an electronics tech, figured it was worth a try to pull it and examine it for any obvious burned components. Turns out there was white corrosion marks all over top board at connector and under several components. I used tooth brush and electronic component cleaner and brushed off all corrosion making sure bristles went under the components where I couldn't see. Put it under a halogen heat light to make sure it was dry, reassembled and have not had a problem since and it has been over six months and several thousand miles. Having CEM rebuilt or diagnosed was several hundred dollars, never mind thousands to replace at these inept dealers, so I am glad I fixed it myself.

What I can't say is if all the other things I replaced were the problem, CEM and shorts have been known to damage fuel pumps, fuel pressure sensors, PEM module and who knows what else. I had the clicking sound you described as well, dash lights would blink, my alarm no longer works, which made the sunroof stop working, crazy to think these two were connected, but Volvo has a sick system connecting all modules and if one goes bad, it impacts others. As a back up vehicle, it is not used daily, but those drain tubes being clogged from sunroof appears to be where all problems begin, so don't know if you checked them yet, but when they clog water can drip right on top of CEM, also reseal every point where water can enter CEM box, wire harness rubber dried out and this is where water got into my CEM box, so I sealed it with rubber auto sealant and check those drains on each side of cowl every few months. Paranoid because car sits under a pine tree and those needles were what clogged my drains up as they easily enter the through the cowl cover.

Hope this helps, but I suspect this is where my problems all began.

Good luck,

 

Free-PPV,
Sorry for the late response. I was busy with my final exams.

I took CEM off and I couldn't find any signs of corrosion. I decided to check the tank for debris and it was dirty. Fuel filter was dirty as well, although I replaced it almost a month ago. So tomorrow I am going to clean inside of the tank and vacuum everything out and replace the fuel filter to see if there is any changes.
The only confusion for me is that if the fuel filter is clogged, the fuel pressure should be low and not high. Mine throws the code for high fuel pressure(p0088 and p0090) which doesn't makes sense.
I also hooked up my OBD II code reader and monitored the fuel pressure while driving. It was between 68 to 74 psi.
I am hoping by cleaning the tank, the problem is solved.
I'll post the results.

 

When you mentioned the clicking behind dash, I had that symptom as well, but I am glad you found no corrosion visible, or any indication of water which is sometimes difficult to see.

I have monitored my fuel pressure consistantly trying to see if there is anything that warns of an impending failure, and so far over past six months, no unusual drops, but when you said you have 68 to 74 lbs, that is much higher than normal which is average 43 lbs in my experience. I will see it rise to 50 range after hard acceleration, so perhaps the codes you are getting are accurate, as this is higher than normal pressure.

You mentioned dirty filter and pump screen again, which is also the same sympoms I had, actually replaced pump twice, cleaned tank, but didn't drop it, so if you can get one of those diagnostic mini camera probes to inspect inside tank to insure it is clean, it might be worth it rather than dropping tank which is a hassle. Did you happen to put a magnet to the dirt to see if it sticks. I found my clogged screen was semi magnetic, as in metal particles which depending where you get fuel, could be contaminated tanks and some of the rust particles are getting past filters, or in some cases gas stations don't have filters on pump, just empty cannister. I know people in business and many don't change filters, they just remove filter inside cannister allowing metal to get into customers tanks. I bought a heavy duty magnet and placed it under pump on outside of tank on metal strap, so no more problems, this is old trick learned years ago with metal tanks that get corroded, so I can only say I have not had any further issues, just to check, I may pull off magnet to see if problem returns. LOL

Simply put, it was a little different than your high pressure situation, but having tried everything twice, I got desperate. I can't say for sure what finally fixed my low pressure drop situation, but I am always curious to learn more about my vehicles to be able to fix everything I can. Just throwing out some suggestions to help. I know how frustrating it all is to fix these Volvo's and what a rip off going to dealers is. Just as an after thought, did you check fuel pump relay? It may be staying on constantly, which would create high pressure code, for as I recall, it cycles based on demand, sort of a on off pump switch. The fuel rail pressure sensor usually does not cause high pressure, just low, and snce you replaced pump, and pumps don't go that regulariy as I have researched, so you might want to get one of these cheap stethoscopes and put it on pump to see if it runs constantly, and not cycle which is normal. Just a thought.

Good luck,