XC90 V8 Intermittent fuel pressure cutout (kinked fuel pump line) Topic is solved

[SHOCKWAVE]

Looking at parts diagrams, it seems Item 2 is used to fill the reservoir via a return from the fuel filter. That makes me believe both tanks are emptied into the reservoir (RHS via being over the reservoir top; LHS via the ejector/transfer pump) until the RHS is below the level of the reservoir.

Maybe the ECM doesn't turn on the transfer until the RHS reaches the top of the reservoir. At that point, fuel only comes from the LHS. But the RHS would still have a decent amount of fuel with no means to get it into the reservoir...

"So, what we have here, gentlemen, is possibly the beginning... of the first international mob war. Unless I've totally missed something." -Agent Smecker

[ggleavitt]

Recap for my own edification (long thread)
-Issue was reported with the car and pump/sender was replaced 6 months by an Indy before the dealer got to it. Pump/sender got replaced a second time by dealer 6 months before you bought it.
-Since you've owned the car, you've replaced fuel filter, air filter, spark plugs, FPS, PEM, throttle body gasket, anything else?
-Problem occurs with no correlation to fuel level per se (1/3, 1/2, 7/8 full).
-You have cleaned all the connectors that you can, no previous issues noted with corrosion.

It's ECM-->PEM for associating the desired fuel pressure (data word?) via LIN bus. It's CEM--->PEM for voltage. It's PEM to the "always on " pump (via waveform duty cycle). Is that accurate?

What else at a high level is missing?

Taking a step back and looking at it from a system perspective, could be the pump even though that's been replaced (2x now?). Could have been the PEM but that's also been replaced. No LIN bus reported errors so we'll maybe assume the physical connection interfaces are functioning properly. I would guess that if it were an intermittent CEM power problem, other modules would be affected. Could be sticky sender (left side sender rheostat might be pretty worn, mine was) but when things are too far off between readings, a code is thrown, at least it was in my case.

To me, that leaves you with another possible failed pump/sender or a possible fault within the ECM itself. But this problem was with the car even before they replaced the pump for the first time, right?

Suppose the easiest thing at this point would be to either replace the pump/sender a third time or simply put everything all back the way it's supposed to go (instructions in VIDA-repair/replace section) and give it another try. If you do, when you put the tank o-rings back, please ensure all the mating surfaces are super-duper clean, the o-ring is well lubricated, and everything goes back on snugly. You'll thank me for this in the summer (even with a new o-ring, I had to do a level sensor twice).

I'm not sure what Xemodex might be able to accomplish, (they can in fact clone your Denso ECM to another one that you send them) but it might be worth a call to describe your symptoms, see if anyone there has an idea of a way to omit the ECM from the equation.

The interesting part about the worksheet from the dealer in your earlier post is there's no mention of any checking software or doing any reloads to the ECM, only replacing the pump/sender.

I'll be happy for you if this turns out to be something far more simple but given all the logical troubleshooting you've done to date, the ECM or the pump seem to me to be the prime suspects.

*edits for typos*

[SHOCKWAVE]

Everything above is correct except:
1) Some connectors have been visually inspected: look brand new so I don’t think further troubleshooting is necessary in that direction.

My analysis at this point:
I’m betting the first pump failed for unknown reasons- maybe age. Indy couldn’t install correctly and the customer was shuffled to Volvo. Volvo installation went bad as well (hose not seated) or they missed something in the tank.

I believe the problem is something “simple”. I don’t think it’s electrical.

What lube is sufficient ? (don’t want to buy the Volvo lube) but I can if necessary...

[ggleavitt]

Probably my verbiage, think we're in agreement inasmuch that your photos note nothing resembling any real corrosion but you had written that you had done some cleaning in taking things apart.

I've used SuperLube synthetic grease and food grade silicone grease (from my dive kit) before but I would think that petroleum jelly ought to work since I believe the fuel tank O-rings are Viton (fluorocarbon).

Good luck with your next steps and I'm looking forward to hearing about how it's fixed. Depending on where the rest of your car is wear-wise, a well running Sport is a particularly enjoyable car to own and drive.

[SHOCKWAVE]

Located about 16 inches from the pump.

[matthew1]

Nice. Everybody have a drink today.

Abscate was on the scent. He gets two drinks.

[ggleavitt]

Know it's noted as solved but I have a few questions for context when time permits, might be good for historical reference-

This kinked hose is on the second fuel pump?

Any record of fuel system warranty work done by a dealer to address symptoms BEFORE the first pump replacement by the Indy?

Listed historical DTC/error (besides the TCM-) was just for fuel pump performance/pressure?

The issue occurred with all levels of fuel in the tank?

Was full throttle or were a number of full throttle cycles associated with triggering the occurrence of the failure?

Was there anything else that can be considered consistent with how this scenario occurs?

Whatever you can fill in once you're done might be good to have in one spot.

Congrats (I think).

*edit for typo*

[SHOCKWAVE]

I’ll do a full wrap up once this is fully resolved. The root cause has been found, but resolution has not been reached. BTW, I appreciate everyone’s help along the way. It would have been nice if the PO just took it back to the dealer instead of unloading it indicating no issues were present. That left me (and everyone else) assuming the FP was good to go.

[abscate]

yyyyeeeeesssss!!!!!!

[matthew1]

I’ll do a full wrap up once this is fully resolved. The root cause has been found, but resolution has not been reached.

Spoken like a true engineer.

BTW, I appreciate everyone’s help along the way. It would have been nice if the PO just took it back to the dealer instead of unloading it indicating no issues were present. That left me (and everyone else) assuming the FP was good to go.

Yep, that was lame of him.

Oh yea... Abscate, it's also St. Patrick's Day... so you get three drinks.