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INJ Fuse Blowing

3K views 1 reply 1 participant last post by  ms6_Wolf 
#1 · (Edited)
I’ve seen this issue on a few forums but no one ever gave any conclusions/solutions to it, so I thought I’d put my mess into the mix.
I had my ride towed to the shop the other day after we coasted off the highway about ten minutes away from my house. I wasn’t doing anything fancy, just cruising along when the power cycled and we stalled out. Once off the road I tried to turn her over, she cranked but would not fire. No CEL and no DTC.
At the shop the flow charts led them to find the blown INJ fuse. They pulled connectors and pinned it out and found no shorts. Once they put her back together she turned over and idled for about 10 secs before blowing the fuse again while throwing a P0091 code. This led them to believe the HPFP internals(Autotech) were faulty. They pulled it apart and found that the shaft was a little… sticky?… hesitant?... not right in one way or another. They called the people at Autotech and then overnighted the whole pump to Cali. Autotech agreed that the internals were bad and rebuilt the pump and overnighted it right back. (Shout out to Autotech for great customer service, the whole ordeal was handled in less than 48 hours from CT to CA and back.)
With my newly rebuilt HPFP installed the shop took her for a test drive, which ended with them stranded 3 miles down the road and then tow strapping her back to the bay. Same conditions, blown INJ fuse, no CEL or DTC. After she sat, perhaps cooled for about an hour they replaced the fuse and she idled and then moved about 100 yds before popping again, and continued doing so at that point.
I’m not sure what the shops next plan of attack is going to be, perhaps to see if she fires after a weekend of sitting to see if it's a heated related thing. That's what I'm leaning towards right now, but I wanted to hear from the people who have seen it all. Any ideas? Are the faulty internals coincidental, related, or a product of the fuse issue? Has anyone heard of similar conditions associated with faulty pumps or blown fuses?
 
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#2 ·
So here is th report I got from my tuner after they've finally decided to throw in the towel.

Tech Notes: Problem verified as described. DTC Procedure has
been performed for DTC code P0091, DTC tree leads to
replacement of PCM.
Tech has checked all sensors, wiring, plugs and pins. No issues
found.
HPFP was found to have minor damage internally, as a result
HPFP was replaced
CAM and CRANK sensors, both scope as directed by service
manual.
When the 15 amp fuse is replaced the vehicle runs, when being
driven the KEY light will flash, and then the security light will
illuminate, once illuminated, the car will stall and the 15amp fuse
will be blown.
At this point, ECS Recommends the help of a Mazda dealership to
troubleshoot the security system and immobilized functions of the
car.
ECS feels that the PCM may also be faulted.


Any thoughts? PCM, Immobilizer, other...? Trying to figure out whether I should tow it to the local dealer who wants $400 dollars to get in the door because it's modified. Or just bring it back to my place and easter egg parts until I figure it out.
 
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