2004 XC70 no start - faulty fuel pump and/or electrical connections? Topic is solved

[enotslim]

Your wiring looks good, I agree that’s rodent insulation only damage and can be taped.

The fuel pump relay function is complex and not just a classic relay. It runs for a second or two on start signal then needs a 40Hz? Ac signal to stay running. It’s possible it’s failing in mode 2 although that shouldn’t inhibit start. The only way to catch that is to monitor fuel pressure during the no start condition

I heard two "clicks" from the general location of the fuel pump relay when the key went to position 3. The first was almost immediate. The second was ~one second later. I think the voltage began dropping long before I heard the second click, so these events were not precisely coincident. I will verify this (although, as you say, failure to maintain should not affect starting).

[enotslim]

Hard to tell at this point what is going on ... wrap all wires ... with addition of curse towards all rodents ... open the tank and inspect what is going on ... also remove the actual pump from its housing ... create emergency "defibrillator" ... Fingers crossed your issues are fixed.

I will remove and examine the pump itself, mesh, housing, etc. Anything else to look for in the pump itself? Evidence of the failure that is said to be hastened by operating with low fuel level? Signs of overheating?

If I don't find an obvious cause at that point I will not have actually done anything to make things better (except for the rodent curse). I may just replace the pump as a sacrificial offering in the same spirit as the curse. Anything else required for this type of Volvo ritual? Incense, chanting, etc.? Does FCP have a kit for this (the Sacrificial Ceremonial Kit)? Likely a big seller.

[Vova585]

Hard to tell at this point what is going on ... wrap all wires ... with addition of curse towards all rodents ... open the tank and inspect what is going on ... also remove the actual pump from its housing ... create emergency "defibrillator" ... Fingers crossed your issues are fixed.

I will remove and examine the pump itself, mesh, housing, etc. Anything else to look for in the pump itself? Evidence of the failure that is said to be hastened by operating with low fuel level? Signs of overheating?

If I don't find an obvious cause at that point I will not have actually done anything to make things better (except for the rodent curse). I may just replace the pump as a sacrificial offering in the same spirit as the curse. Anything else required for this type of Volvo ritual? Incense, chanting, etc.? Does FCP have a kit for this (the Sacrificial Ceremonial Kit)? Likely a big seller.

You totally made my day with "Sacrificial Ceremonial Kit". I think you just gave FCP new product idea.
If you can justify putting in a new pump and it is not cost prohibiting issue, it is nice to have something that is 99% will not cause problems. In case you will see lots of debris in tank you can use any hand pump for fuel transfer to suck it from there or any other similar device as long as hose or nozzle that it uses is gasoline resistant(i would avoid using electric fuel transfer pumps unless located outside of the car and in well ventilated area). I would also use engine oil to lubricate the new rubber gasket prior to instalation and note orientation of the fuel level sensor(on my car it has 2 sensors for each side of the tank so with replacing the main pump the gauge is slightly off,but not enough to justify replacing the other side level sensor.
What makes me scratch my head is the fact that we were unlucky to have a persistent problem to properly conclude what is going on with car. I understand that impulse is to have some 100%working part/s so you have at least some clarity of what is going on. At this time we were not able to replicate the issue..if you will end up replacing the pump with new one and issue will repeat itself, I would have a spare used fuel pump relay in a glove box or just a jumperwire to instal inplace of relay and get home.

[enotslim]

There are actually three "clicks" when moving key from position 2 to 3. The first is immediate coinciding with fuel pump voltage spiking to ~11.8 V. The second is less than one second later coinciding with voltage dropping toward zero. The third is at 1-2 seconds coinciding with I don't know what. The first click is masked by key noise. Missed it previously. Had to listen/localize more carefully to hear it. In guessing first and second clicks are fuel pump relay opening / closing.

I remember reading that VIDA/DICE allows one to intentionally direct 12V to the fuel pump, presumably for testing purposes. Would this also allow me to start the car (and get home) in a no-start situation that results from failure to deliver 12V to the pump at start up and beyond? Due to a relay or any other cause. I like the idea of being able to turn this voltage on and off via software.

Will VIDA/DICE also read the voltage present across the fuel pump leads in real time when cranking under a no-start condition? Without disassembling everything? That would be invaluable. (Well, almost. )

When should a 12V rescue be delivered? Crank first, then immediately activate the pump or the other way around? I assume 12V should not be delivered continuously to the pump if ignition fails and fuel is not begun consumed, correct?

[jonesg]

I would spend the money on a vida set up before the pump, you can monitor the pump duty cycle.

Direct power to the pump will (with a good pump) pressure readings 80 psi and beyond. It should be regulated by whatever system your uses.

Pulling the pump for inspection, be aware it is connected to the second fuel feed on the other side of the saddle tank, don't just pull it out without attaching rope to the other end so you can pull it back into position without kinks.
You can test without pulling it out anyway. And you should be able to rig it to get it home.

[enotslim]

Thanks. My searches missed these videos that are very useful. The culprit was a defective PEM - a component my car seems to lack - but still useful approach. The scanner used is also quite informative, and not limited to Volvos, as VIDA/DICE would be. But it's also $700-$800.

I've known about snaking the connector across the midline, which is in part why I did not open the fuel tank right away. Didn't want to do more harm than good. But as you say, the pump alone can be removed and tested without disrupting the harness or any components on the other side as in the video below.

Now that I know how to test voltage delivered to the pump the best course may be to drive until the no-start condition recurs and diagnose at that time. I haven't experienced fuel pump issues while driving (stalling, etc.) but I also have barely driven since this issue arose. If I can then diagnose and then activate the pump with VIDA/DICE to start the car and can get home, the rest will be relatively easy assuming the failure persists (although persistence may be unlikely). Worst case scenario will be stalling 2 floors deep in my low-clearance garage at work - again - and not being able to force a start. But I'm getting really good at calling for a tow.

I think I need experience with VIDA/DICE before finalizing a plan.

[Vova585]

In case you have the issue with defective/failing fuel relay or any other electrical wire which intermittently loosing ability to move electricity due to compromised wire integrity or ground connection vida dice will not help you at all. My guess is that vida/dice has the ability to "test mode" the fuel pump as you described. But it will likely be doing that by using command side of the fuel relay and command taggle to switch from post 4 to post 5 which will create electricity flow from 3(hot all all times) 5(pathway of 12+ to pump).
Being a hamble man and lacking all the tools that honorable Ivan from PHAD has I would select to likely replace the fuel pump relay with brand new one(probably $35-70 for oem) and then either drive like that with hope that issue will never appear again. Or another alternative is to say to "to hell with that the fuel pump 20 years old and I hate the new cars and their prices, so I would put a new pump since old likely will fail anyways soon". Yes it can be considered "parts cannon" but those would be 2 very common things to fail and by eliminating them you might hace some peace of mind that you can drive your car around with less fear that it will die on you any moment.
Another possibility that you can try is to see if car will run with "bridge" at the site of fuel pump relay. (Car stooped-remove relay-install wire bridge from post 3 to post 5-make sure you hear pump running-try to start the car and see if it will be working ok) this method might be an alternative to buying a new fuel pump relay and possibly be a crutch to get you home in case car is loosing control over command side of the relay(in this case even new relay would not help us). Hopefully car is not too smart to recognize that absence of control side of the relay and will shut down something else(hard to tell without electric diagram)

[enotslim]

Pulling the relay led to failed starts. A few cycles of combustion on the first 2 start attempts. No combustion on third and later attempts. Reinsert relay and quick start up on first try. I didn't monitor voltage at the fuel pump during attempted starts with the relay out. I assume it was flatline zero.

Turns out I do have a working copy of VIDA available on an older laptop (MacBook Pro 2013) running in a Windows XP virtual machine. Forgot about it because I ended up not using when I was torturing a 1998 V70 T5 (this car included in VIDA 2014D). I'll attempt to connect to the car ODBII after a fresh backup of the retired laptop just in case something goes funny in battle. I will explore and consider if I can get the drivers working (my VM driver experience isn't great) in order to use a scanner like DICE for interrogating faults and manipulating settings on the current car 2004 XC70. The electric circuit part of VIDA on this virtual machine keep crashing (Acrobat crashes). Hopefully I can find this data somewhere that will integrate with VIDA. I think I also have a static pdf of the electric circuits somewhere.

[jonesg]

The other clicks when cranking are the delay relay, it shuts off power to all acc's and headlights during cranking so the start system gets full clean power.

I opened up a dead volvo pump and found the motor brushes completely melted in their holder, the solder connections melted off, lots of brown black burn marks, theres no mistaking it. The elec motor is made by AC Delco in korea, I bought a new motor from autozone and soldered it into the original pump housing, $65.

Get that vida running so you can use the bi-directional controls and look at the duty cycle. And try to keep the tank above half full.

[abscate]

I thought you replaced the relay with new up thread? I think you have narrowed it down to relay , wiring, or pump with the lack of fuel at the valve diagnostic on no-start. Vida won’t tell you much if the pump or relay are dying, it’s good for missing signals more that intermittent

Your car will have an FPR built into fuel delivery back at the tank, not on the fuel rail.