Exactly what I was gonna say!! They get corroded and therefore don't make contact properly and seem like they fail.... unplug and clean !

 

I received a replacement PEM / fuel control unit. Hooked it up and the car wouldn't start. Before accidentally pushing my car into the nearest lake I plugged my old one back in and she fired right up. So it was a bad unit. I just received a replacement-replacement, plugged it in and she started perfectly. I test drive the car up and down the highway for about 1/2 hour with no issues.

However let's keep in mind that in the past the time the car sat was directly related to how long it worked before acting up again; and it's been sitting for about a week. So I'll drive it for a while and report back.

The upside to replacing all the parts I have is that the average gas mileage has increased 4-5 mpg. So having mostly new parts in the fuel delivery system hasn't been a total loss.

Will report back with a final verdict soon. Thanks again for all the help!

 

Just wanted to share an update regarding this situation. So far replacing the PEM seems to have done the trick. I say that with a slight bit of apprehension as the car ran great for a week or more after replacing some of the other parts. Intermittent issues are so fun!

So I'll keep on driving and if something changes post back.

Thanks to all those that chimed in and a special thanks to ES6T, you're a great resource on this forum!

If anyone is interested I did a quick tutorial for replacing the XC90 PEM located here:
https://volvoforums.com/forum/volvo-...utorial-71534/

 

Hello, I am having trouble with my 2006 s60r that seems similar. It is bucking when at cruising speed and the check engine light is coming on. Took it to a dealer, they want to replace the fuel pump then the tank if that doesn't work. Here is the invoice description: "misfire all 5 cylinders this may be caused by low fuel pressure. Perform sample check and we found dirty fuel on inlet side of filter. Tech replaced fuel filter and recommended customer return vehicle to recheck filter.." I really don't want to play guessing games on my dime, any ideas? Thanks!

 

First of all, is the vehicle still acting strange? If not the filter may have done the trick. However I bet a lot of people have "dirty fuel on inlet side of filter". So for what it's worth here are my thoughts...

The dealer is probably thinking the misfire is caused by a fuel delivery problem which is a fair and probably accurate assumption. Here are the things to consider:

1. Did they actually check the fuel pressure?
This will tell them more accurately what is going on, in my opinion they should have but might not have.

2. Fuel filter is a common starting spot
But many times not the culprit...you always hope it is because they're fairly cheap and easy to replace.

3. When is the car hesitating?
Only on the highway? On city streets? On both? When going up hill or flat surfaces or both?

4. A Volvo dealership or European specialty shop should be able to narrow it down more
They should have a diagnostic computer that can narrow things down specifically depending on the code. Autozone will give you generic codes that can be helpful too.

5. Fuel pressure sensor
The issue I was having is many times the fuel pressure sensor. I read about others mentioning the same symptoms as I had and many of them solved it by replacing this part. If you're interested I have the old part from my car. I'm pretty confident it works because replacing it with a new one didn't change things for me. Much cheaper and easier to get to than the fuel pump. It sits right on top of the engine at the end of the fuel rail.

6. Fuel pump might be the problem
That's just an expensive risk to take. I did mine myself and it was still expensive.

7. Not sure if you have a fuel control unit (FCU) / pump electronic module (PEM)
A quick search looks like you do but I'm not positive. This is what my issue was. Again, not cheap ($300) but if it's not working your car runs like crap.

8. Replacing the tank seems weird
I'm not sure why this would be the issue. It is however very expensive and a great potential money maker for the dealership. I'd avoid this route unless they had a really good reason why the tank, that's been fine for 7 years, all of a sudden isn't fine anymore. They'll claim dirty gas but you can replace a lot of filters for the cost of a tank.

Summary...the next cheapest thing to try is the fuel pressure sensor followed by the fuel control unit and lastly the fuel pump. Make sure there aren't any active recalls that, by chance, might fix a known issue.

Good luck! It's not fun chasing these things down. My money is on the fuel pressure sensor with the info I have so far. But I was wrong on my car so no promises!

Hope you find what's wrong with yours quickly and affordably, anyone else with ideas by all means chime in!

 

The car only seems to be acting up when trying to maintain a steady speed-especially around 40mph or lower. The dealer did replace the fuel filter, it has not solved the problem. I also do not know if the dealer actually checked the pressure or just got misfire codes and are just guessing. Thank you for your advice, I'll let you know how it turns out!

 

Very helpful thread, and I too have been having nightmares with the same type of problems and have also changed everything but gas tank. What is mystifying is that Volve dealers can't seem to have diagnostic smarts to properly pinpoint these fuel pressure issues.

What is strange is that my XC90 2.5T runs perfect for first ten minutes of driving, and this is consistent, so how can it be a fuel pump again having replaced with two already due to dealer misdiagnosis. So given I have yet to figure this out, and dealer was no help at all, they simply appear to be guessing.

I had the typical p0087-89 codes, pressure was dropping to below 10 PSI every time I would hit full acceleration only after about 10 minutes of driving. That is what is throwing me for a loop, and I can't imagine gas tank could be the problem even if it has some residual dirt in tank. So now I am trying to determine if having full tank verses 1/4 tank has any impact on problem. Runs perfect unless I floor it. Strange, so anyone have any ideas after all this time.

 

Very useful thread. Thank you so much for all the great information!
I have a 2006 Volvo XC70 that is doing the exact same thing. I wish I had read this before trying to (expensively) figure out the problem.

So far I have had:
1) New fuel filter and hose that was collapsed in the engine replaced
2) New fuel pump, which after picking it up and filling with gas, leaked the whole tank of gas out. I had to have it towed to the mechanic as we were all stranded at the grocery store.

And it is still doing the hesitation, feeling like it's about to stall, and lurching. It does it when I'm cruising down the highway, at a dead stop, and while accelerating. I will definitely look up my VIN for recalls but also check out if I have a PEM that seemed to fix your issue.

 

Greetings,

Sadly, there are many things which can cause your symptoms, and it is difficult enough to find problems with a scanner, but without codes, it is impossible. Best advice it so go to your local AutoZone or AdvanceAuto and get a free scan.

Having also changed fuel pump twice with same issue, turned out to be dirt in tank which I don't know where it came from. Plastic tank, so there was rust particles which were clogging up fuel pump screen, so did you examine old fuel pump to see if it was clogged up? I suspect some gas stations do not have their pump filters installed to save money and time as they get clogged up all the time. Got this tidbit from a friend who delivers fuel to stations. What I did instead of pulling tank out and cleaning it out, I put a powerful magnet under fuel pump attached to steel tank strap. Amazingly my issues of suddent fuel pressure drop ended. Been over 7 months, no more engine dying and hesitation, stalling, etc. If it wasn't such a pain to pull pump, knowing what I know now, I would have dropped magnet into tank to pull out metal chips. Pull up your codes or buy one of those cheap data port diagnostic modules and monitor everything on your smart phone. I was able to watch fuel pressure drop and engine cut out, so it was the only way I found out what was wrong. PEM can cause similar erratic engine dying if bad connection, so worth checking and cleaning plug and terminals and see if their is any corrosion which is common. It also could be fuel pressure regulator on rail, easy fix, but pull codes to narrow down problem.

Good luck,

 

Thanks for the suggestion FREE-PPV. Unfortunately I live in Alaska and we have no AutoZone or similar place that can pull codes for free. My Check Engine Light has not always come on during this problem, which has been happening and intermittent since the spring. Also living in Alaska, I would bet money the gas stations don't have the pump filters installed to save money. The first mechanic I took it to said the fuel filter was so clogged he wasn't able to check for any other issues until it was replaced. So that was the first step. After that, it was still acting up and the CEL did come on, so they pulled codes off that said something about fuel pressure was low. I don't know the exact code but it seemed like similar ones to this original post.
After the fuel pump was replaced at a second mechanic, the CEL came on again, and the second mechanic said the fuel pressure sensor was the code, but he checked that and it didn't seem like it was a problem, so he reset the CEL and it hasn't come on again, even though I have experienced the hesitation. I am going to bring it in to see if he can visually inspect the PEM to check for corrosion. We live in a rain forest here in Southeast Alaska and it is very wet. I've only had the car here for a few years, so it's possible it could have corroded with the pretty much continual water. We are having weather right now that NOAA calls an 'atmospheric river'.
I can also check out rust or metal in my fuel tank. Do you think there would be any harm in dropping a magnet down in the tank and seeing what comes up? Like would any other parts or components be damaged by doing so?
Unfortunately there are only three mechanics in town that work on foreign cars. The first one changed the filter and collapsed hose and then wouldn't get me a quote on the fuel filter after I hounded them repeatedly over the course of a couple weeks. So I tried the second mechanic, which didn't notice dirt around a seal when replacing the fuel pump, causing a full tank of gas to leak and and me to have it towed from the grocery store. The third mechanic I went to with a previous VW, and he is chauvinistic and price gouges, at least the women. My husband is less mechanically inclined than me and I refuse to play dumb and have him take my car in to the shop.
Thanks!

 

Greetings,

Yes, your symptoms are similar to many others with same problem. When you mentioned fuel filter totally clogged, that says it all, you got bad gas with a bunch of metal rust chips for sure, I replaced two filters and two fuel pumps because of clogs, didn't drop tank, tried to clean it out from pump opening, but tank has two bellies to make room for rear drive shaft, so if you dropped magnet down filler, you would not get to problem area in tank just below pump. I put magnet on tank strap right under pump, never had another problem, so I know it was full of metal chips from gas station tanks, common problem, and probably worse in AK given your location in rain forest plus crazy temperature swings which causes more water to be in tanks rusting them out. If fuel pressure regulator does not fix it, or PEM is not corroded, then you might want to drop magnet in tank and see what comes up to see if that is possible given there is probably crap in both sides of tank. If you have no places to pull codes, buy a diagnostic module on ebay, they are cheaper than buying whole unit, then you download app on your smart phone and you can read every engine function in real time. Real life saver for me as I went through several mechanics too.

Good luck,

 

Was having this SAME issue in my 2005 XC90 2.5 (99K miles) and replaced

Fuel rail pressure sensor
fuel filter
Spark plugs
Ignition coils
Mass air flow
Fuel pump
Cleaned throttle body

Nothing worked! Car was barely driveable with all the stuttering and loss of acceleration! We were at wits end and found this thread.. located the Pump Control Module, cleaned and greased the connector and voila! Ran so perfectly we bought the Ford/Bosch replacement and car is smooth as can be. This thread is a lifesaver!

 

on my 03 xc90 i cant find the PEM anywhere. not in the wheel well not at the passengers back seat. any good guess?