Fuel rail pressure still too low AFTER replacing sensor, fuel pump, PEM and filter Topic is solved

jonnydrums · Post by **jonnydrums** » 15 Jul 2020, 16:23

Hello all-

I'm at my wit's end. The vehicle is a 2005 XC70 Turbo AWD with approximately 150K miles.

Original problem (from a few weeks ago): wife drives home one night with everything seeming fine and shuts the car off. Next day, it will crank readily but no start, no run. Weeks of analysis and repair attempts followed.

As of today, July 15, 2020, I have the car in a state where it will start and it will idle/run, but performs poorly under load. I am super frustrated to be only this far but not done after everything we have tried.

Current codes are 0087 Fuel Rail Pressure too low and 2177 Too Lean off Idle (Bank 1). At this point I have done various tests and have replaced the fuel rail pressure sensor, replaced the PEM (and cleaned the heck out of the wiring hookup for it), replaced the fuel pump, and replaced the fuel filter.

Here is a running log I have been keeping the whole time since the beginning of the problem, showing my thinking at each phase and the steps taken to get to this point..

Initial symptoms: Car would readily crank but would not start, nor would it run
Battery check: passed
All fuses checked, with particular attention paid to any fuses and relays even remotely related to starting/ignition/fuel. No bad fuses or relays found. Cannot access fuel pump relay without significant removal of parts from fuse box assembly
No CEL or codes present at this time
During testing, occasional message about immobilizer popped up. After reading many forum posts on immobilizer issues, proceeded to test alarm function and manipulate wheel/lock system many ways. No change in result. No further immobilizer messages popped up after initial few instances.
Applying starter fluid through air intake resulted in car starting and running briefly, petering out as starting fluid used up. Conclusion: supports theory of fuel delivery issue.
Next steps:
⦁ removed rear seats and uncovered access to fuel pump and sender unit
⦁ listened to fuel pump with handle of screwdriver, determined that is is at least partially functioning as it makes noises when key put in position 2 and/or start attempted
⦁ Used electrical tester to determine which wires are responsible for sending power and control to fuel pump, checked continuity to wiring harness that feeds PEM module located under car near fuel filter.
⦁ Wired battery power directly to the lines on the fuel pump (bypassing rest of system) to test that. In this configuration the car starts and runs! But it is also evident that without finer controls it does not properly adjust as a normally running full system would.
⦁ Restored original wiring config, removed fuel filter and drained it. A significant amount of fuel spilled from the disconnected lines on both sides and from the fuel filter itself. Blew through filter to test for blockage. No obvious problems found, although filter is very rusty and crappy looking.
⦁ Checked fuel hoses at least where visible, did not see any clear evidence of hose faults, or connectivity problems.
⦁ Under hood, checked Schrader valve at fuel rail (this has been done at various times throughout testing) and only a little bit of fuel poured out weakly.
⦁ Visual inspection of fuel rail pressure sensor did not reveal any obvious faults.
Theory: Not enough fuel being sent to fuel rail
Next steps:
⦁ Tried simply adding more fuel to tank after reading that sometimes sender unit does not properly read fuel level (gauge indicates over half full) and therefore may send bad info. No change in results
⦁ Visual inspection of PEM module showed it to be very old and corroded-looking, and the wiring plug into it is not in ideal shape either.
⦁ Replaced PEM module. After this replacement, the car will now start and run. However it runs inconsistently..seems fine for a minute, then runs rough then fine again. Road test proved that although car will now start and run, it is not dependable and performance under load is erratic at best. It will always start and run again but every time it runs unreliably.
⦁ At this point CEL came on and codes were thrown. Initial result was two codes:
⦁ P0087: Fuel rail pressure too low
⦁ P0088 Fuel rail pressure too high
⦁ Despite (or maybe due to) directly contradicting codes, determined that next thing to try was to replace fuel rail pressure sensor.
⦁ Cleared codes and replaced fuel rail pressure sensor. Initial results seemed better, but further testing showed a return to inconsistent performance. Now only one code though: P0087 Fuel rail pressure too low
⦁ Tested wires at connector on top of fuel tank, seems ok, shows voltage when key put to position 2
⦁ Tried a configuration with old PEM and new fuel rail pressure sensor. Result: Car would sometimes fail to start, and when it did start performance was consistently poor. So I re-installed the new PEM (Theory: New PEM with new shiny pins helps some but maybe connector itself is corroded enough to cause inconsistent performance even though car will now start and run (albeit inconsistently)
⦁ Acquired and used electronic cleaner to attempt cleaning of female plug that connects to the PEM. Performed two rounds of cleaning to extent possible, allowed to dry, reconnected and tested car. Same result. Will start and run but performance is inconsistent and suffers under load.
So with these summarized facts (this was about a week ago before I replaced the fuel pump itself):
1) when fuel pump is connected directly to battery, car started and ran
2) after reconnecting everything with normal wiring config, then replacing the fuel filter, the PEM and the fuel rail pressure sensor, the car will now start and will run but performance is inconsistent and still getting code P0087 "Fuel rail pressure too low"
3) Clearly fuel pump works at least partially, despite the current condition of inconsistent performance because otherwise it would not start and run at all given everything above
My thoughts at this point - Do I still go ahead and replace the fuel pump itself? Before plunking down that additional $200-300 and embarking on what kooks like a fairly hard and sketchy job of replacing the pump itself...Should I try (even though I already replaced both PEM and Fuel Rail pressure sensor (and filter) to take the sensor out of my other, working, XC70 and see if that helps (maybe I got a bad new sensor)?Or am I missing something else here?

My experience sounds a lot like this guy (although I do not have the tools to test the actual fuel pressure number): https://www.volvoxc.com/forums/archi...p/t-27514.html
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UPDATE 07/15/2020
Replaced fuel pump. Connector for wiring had correct pins but had to be slightly filed down to accept the plug. Thought plug was fully inserted after file down.
Initial test: back to square one...would crank readily but no start, no run and a whining noise from engine compartment (electrical sound). Pressed wiring plug harder into fuel pump and it clicked in. Tried again.
Sudden fuel spray inside car...the send hose from the fuel pump's outward tube (on top of pump) had come off, almost as if once plug inserted all the way it was too powerful, or maybe when we replaced the pump we just hadn't attached it fully and it did not reveal itself until plug properly connected.
Ensured hose fully connected, cleaned up, prepared to test again.
Car started and ran. Did not die, idled normally. Tried to drive away.
On this run and all following runs, it seems ok under load for like the first 30 seconds but then after pulling onto road and trying full acceleration, it always seems to struggle under load. Was able to limp it around, got to a parking lot, let it idle a while. Revving while in park works perfectly every time.
Cleared codes, restarted car. Drove again. Again, seems fine for like 30 seconds then starts to suffer under load, sometimes recovers, sometimes dies. Will always restart fine every time.
Checked codes again, now it is a laundry list:
0087 Fuel rail pressure too low (x2)
2177 System Too Lean Off Idle Speed
0300 Random/Multiple Cylinder Misfire
0301 Cylinder 1 Misfire
0302 Cylinder 2 misfire
0304 Cylinder 4 Misfire
0303 Cylinder 3 Misfire
Limped it home and parked for the night.

Today I even tried putting the old fuel rail pressure sensor back in. It did not help, so I re-installed the new one. I am about ready to give in and go to a mechanic but after all this work it seems like a failure to do so and get charged for the mechanic to probably repeat everything I already tried. I also looked for literally an hour to see if there was some obvious broken hose or wire, nothing like that found...I can see a few spots throughout the car where previous "mechanics" cheesed the process of removing or replacing things and broke little clips and things, but no obvious culprit. I cannot for the life of me figure out the last stage location of where the fuel actually gets into the fuel rail itself (suspecting at this point because I have replaced almost everything leading up to that point in the chain maybe I have a blockage or something between the filter and the fuel rail somewhere?) but I cannot see anything obvious and don't want to disassemble half the motor to find out. Some people mention fuel pressure regulators but I'm not sure this model even has one (apart from the already-replaced sensor) and if there is such a thing I sure can't find it. Frustration is at peak level.

Does anyone have any ideas?

Post by **abscate** » 15 Jul 2020, 18:10

It’s very easy to kink the fuel line in the saddle tank design if you don’t run messenger line to pull the ejector pump line to the right place

This is described with photos in the xc90 forum by user shockwave

jonnydrums · Post by **jonnydrums** » 15 Jul 2020, 18:33

Hi abscate, thank you for replying. What I don't get about that is...I did use a messenger line to pull the hoses back through from the passenger side to the driver's side to reconnect to the sender side. I followed the techinique that we've probably all seen in several videos of tying it to the old fuel pump hoses before extracting pump so I could pull the hoses from the new pump back through the channel of doom when swapping the pump. Also, if we start at the point in time where I had replaced PEM and fuel rail pressure sensor, from that point on the conditions (would start and run but would not perform under power and fuel rail pressure reads as too low) and/or symptoms symptoms were the same before and after replacing the fuel pump itself and associated pulling of tubes with string.

Please don't get me wrong, I'm thankful for any and all replies and to be clear I am not at all dismissing or discounting the idea that there may be a hose somewhere I can't see that is kinked. In fact I am thinking that's one of the only things left as a possibility at this point considering all the parts I have already tested and replaced as stated above. Trouble is I can't even see any more hoses or locations other than those I have already dealt with, not unless I get a lift and take off half the bottom of the car

Point being if it's a kinked hose I don't know where else to look and it's odd that replacing the entire pump made no difference. It's got me wondering if the potential kink is somewhere AFTER the fuel filter in the "chain" that leads to the fuel rail but damned if I can figure out where.

Post by **jonesg** » 15 Jul 2020, 21:59

autozone might have a loaner fuel pressure guage to try.
But it probably needs testing under load, got vida?

Post by **abscate** » 16 Jul 2020, 03:04

Pull the fuel pump out again and inspect the hoses for kinks. Shockwave had the dealer install his pump and they kinked it, twice. It was a gnarly one to diagnose as it would periodically unlink and work well.

Post by **oragex** » 16 Jul 2020, 05:27

We have indeed seen in-tank fuel hose kink, however you appear to say that direct power to the pump seems to solve the problem. Would suggest a fuel pressure gauge at the schrader valve to read the pressure live. The replacement PEM was used unit ? Always possible someone sold an already faulty one - may try another used one (new one is too expensive)
Not sure about the next thing but maybe a lead. I guess the way the Anti-skid works is but cutting the gas, so perhaps that could be involved ? Any leak traces on the CEM ? How is the DEM looking, lots of corrosion on the cooling plate ?

Post by **abscate** » 18 Jul 2020, 05:27

Would suggest a fuel pressure gauge at the schrader valve to read the pressure Live

^^ This

I don’t see any fuel rail pressure measurements with an independent gauge.

That’s the missing data.

When my PEM went I had no codes but the fuel pressure went to 52psi initially, after a minute started an oscillation of aBout 10-15 psi

If I went into Vida, the pump was solid at 52 psi. That told me pump was fine , PEM was bad.

Diagnosis time, 7 minutes

Post by **volvolugnut** » 18 Jul 2020, 17:57

There is nothing complicated about a fuel pressure gauge. An air compressor tank gauge (0 to 100 psi) borrowed from an air tank will read what you need. Remove the valve from the schrader valve and connect with rubber hose and hose clamps. Be careful to have no leaks. No ignition source or flames. Drain all fuel and let dry before returning gauge to tthe air tank. Usual disclaimers - you assume all risks.

If pressure is low and you think the fuel line is kinked or pinched, disconnect the fuel line at the rear and try to push a weed eater line through to front. You should be able to get an idea where the kink is from how much line you push through.

volvolugnut

jonnydrums · Post by **jonnydrums** » 19 Jul 2020, 18:38

Hey all-
I wanted to provide an update and thank you all for your replies. As of today we have pulled and re-re-installed the new pump. I had drained the tank almost entirely, I added back in one gallon cause it would not start at all. After adding the one gallon of gas, it now starts but won't hold idle for very long. Is it that simple? Do I just need to add maybe another gallon or two before I get despondent? Before you answer read on please.

Abscate and others were correct that the hose leading out of the new fuel pump was kinked...

see here looking down side of fuel pump at about 3 o clock on the pump:

Those show the kink close-up and another view looking down from a little higher. I got in there today with the pump half out and a endoscopic camera and could see that one side of the hose loop that comes out of the pump was kinked and had gotten itself under the pump when we installed.The hoses were indeed trapped under the pump. I feel dumb about that but anyone who has done this knows it is hard to finagle everything into the hole considering how it is set up and the floater and the proximity of external hookups as well.

Which also explains the other thing I noticed now and in the beginning....the fuel pickup disc on the other side (sender side) was unable to be pulled far enough over (via the hose) to attach into the bottom of the spring assembly on the sender unit,at least until I did this check and re-reinstall today (which I hoped would be the end of it).

However, it still doesn't explain why both old pump and new pump after other repairs both led to start and run but die under load, but in any case, I feel it proper to report that in today's case the hose WAS kinked so I thought I had the problem really isolated. But sadly after doing my best to realign properly, deal with the kink as much as I could,buttoning things up and adding back in a gallon of fuel to the little that was left, it now starts but won't hold idle (even though it can take a little rev) for more than 30 seconds.

Here's the thing though. Three things:
1) When we pulled the old pump the very first time I noticed the pickup disc was not connected to the bottom of the sender assembly in the first place but I didn't think much of it cause at the time I didn't know it was even supposed to be connected
2) Now with this new pump, there were two problems straightaway....when it arrived at my house and we unpacked it, it was easy to see that the hose was already tending to bend the opposite way from how I now know we want it to... right where it leads away from the pump at the bottom. This is exasperated by pulling through to the other end, and as any of you who have changed this fuel pump surely know, when you are dealing with the fuel lines and the floater arm working the pump back into its hole, it's impossible to see the hoses once you get the pump far enough into the hole to get that floater thing to pop back into place.
3)that said we unkinked it as much as we could and installed the pump turned a bit to get it cleanly in, then re-oriented it (I know you have to line up the arrow so everything is in proper orientation) when I could feel that it was no longer sitting on any hoses, and then on the sender end it was a bear but I could finally get enough hose length to just barely get that pickup disc re-attached to the bottom of the sender unit. The biggest pain here is that the very clip which attaches the disc to the bottom of the sender spring loaded column is also the biggest impediment to pulling the hoses through the tank to the sender side when you install a pump. See picture depicting tank and routing, with red/yellow arrow indicating the trouble spot as far as pulling through the hoses goes.

And of course just like on the pump side, in the sender side you have to just trust (cause you can't see) that as you compress the sender (and yes I made sure to re-attach the wire that goes to the sender) to install it, you have to trust that the disc stays attached at the bottom, which it felt like it did.

Anyway as of this moment (after having to push down the plug on top of the pump to get it to click all the way),with one gallon of fuel added back in the car now starts but dies after maybe 30 seconds of idle.This is a new result. We've gone from no start no run to start and run but die under load, to start and die after brief idle.

I know it sounds easy to just go get more gas but I don't want to keep adding and subtracting gas (getting headaches haha from all the fumes) if I need to be doing something else first. At this point I am also considering taking all the knowledge I have gained from this and although it sucks, buying ANOTHER new fuel pump, the most expensive and "official" one, and trying to install that. Maybe. If I get another new one hopefully the hoses will not be packed in a way that encourages them to go the wrong way.

p.s. from so much messing with the disconnects over and over I bet some of them are starting to kink up too.

Frustrated but thankful for all the replies, and I'm not giving up yet.
edited to properly add images, last edit at 10:01 pm July 19, 2020

jonnydrums · Post by **jonnydrums** » 19 Jul 2020, 18:43

oragex wrote: ↑16 Jul 2020, 05:27 We have indeed seen in-tank fuel hose kink, however you appear to say that direct power to the pump seems to solve the problem. Would suggest a fuel pressure gauge at the schrader valve to read the pressure live. The replacement PEM was used unit ? Always possible someone sold an already faulty one - may try another used one (new one is too expensive)
Not sure about the next thing but maybe a lead. I guess the way the Anti-skid works is but cutting the gas, so perhaps that could be involved ? Any leak traces on the CEM ? How is the DEM looking, lots of corrosion on the cooling plate ?

With everythig I just posted above still as is, I also wanted to specifically answer oragex: the replacement PEM was new as was the new fuel pump and new fuel rail pressure sensor. And visual inspection at least as much as I could see with naked eye and snake cam did not reveal any obvious kinks between filter and fuel rail (up to the part where the hose tuns to metal).