2007 XC70 Fuel pump fuse repeatedly blows

Post by **abscate** » 26 Jan 2018, 13:49

Thats a dead, dead, dead battery

P2 cars do not like low voltage, so don't do anything until you get a good battery in there.

Post by **mtd240** » 26 Jan 2018, 15:14

Issue(s) solved!

Replaced the battery (side mission I guess - didn't fix the fuel issue).
Went back in to pull the fuel pump out. Pulled everything - found that the fuel hose had kinked in multiple places. Starved the fuel pump (hence no pressure).

I reinstalled it all - much more carefully (and oddly enough, much more quickly) than the first time. Didn't worry about clipping the secondary suction line to the second level sender - just plugged it in and ran the tiny messenger wire I used up and out of the tank. Should keep it from moving too much, and it prevented me from having to twist and turn that suction line to get it clipped in the right orientation (more chances for kinking).

Car started on the first try. Lesson learned (again): I should always assume that broken things are my fault!

Also - the intermittent fuel level sender signal was a separate issue. Not sure how this happened, but I taped it up and didn't bolt the access plate down too hard this time.

Post by **RickHaleParker** » 26 Jan 2018, 16:43

Looks like you twisted the hose on instead of pushing it on.

Post by **mtd240** » 27 Jan 2018, 12:22

RickHaleParker wrote: 26 Jan 2018, 16:43 Looks like you twisted the hose on instead of pushing it on.

Not sure what you mean? The picture just shows where one of the wires (white - goes to the PEM) was shorting on the fuel pump access cover.

Drove it awhile today, then the "Power System Service Urgent" light came on (codes CEM-1C06 and CEM-1C08). Guess my new alternator (Bosch 140A) was faulty out of the box, or running it for 10 minutes with a bad battery killed it (shouldn't have). New one is on the way. The fault only happens when the car has warmed up for awhile - I went out and restarted it after an hour or so, and it took ~15 minutes of idling for the alternator to stop working again. It passes the VIDA "Quick test" when cool, and fails when hot.

Hopefully this isn't due to some other fault in the electronics.

Post by **abscate** » 27 Jan 2018, 12:39

Check those cables for either resistance ( by voltage drop) or heat (IR gun) to see if they are a problem.

Post by **mtd240** » 27 Jan 2018, 13:08

abscate wrote: 27 Jan 2018, 12:39 Check those cables for either resistance ( by voltage drop) or heat (IR gun) to see if they are a problem.

Voltage drop from battery positive terminal to alternator B+ post: 0.124V (max). Drops as the car warms up.
Voltage drop from battery negative terminal to ground in engine bay: 0.1V.

The alternator output zeroes out as soon as I put a high load (e.g., just the headlights, or just the rear defroster) on the system, and doesn't return to normal even after shutting off the loads that were added.

Post by **RickHaleParker** » 27 Jan 2018, 13:36

Belt condition and belt tensioner can cause the CEM-1C08.
Have you had a battery charger on it lately, too high of charge voltage can cause CEM-1C06.

Post by **mtd240** » 27 Jan 2018, 13:48

RickHaleParker wrote: 27 Jan 2018, 13:36 Belt condition and belt tensioner can cause the CEM-1C08.
Have you had a battery charger on it lately, too high of charge voltage can cause CEM-1C06.

These codes are only from driving the car around for around an hour after clearing all DTCs - no jump starting or battery charging.

The belt tensioner bearing has a little bit of play in it (no noise) and the belt itself looks fine (no cracking). Not sure how that would cause the alternator output to suddenly zero out after warming up for a while? Steering and A/C work fine after the alternator voltage drops.