Fuel Pump Fuse Blowing

[trinity_gt]

Went to get my 02 GT out of winter storage today. It has a Kenne Bell 1.7L 'screw and there's a BAP wired into the OE fuel pump. The car has had this configuration for many years now with absolutely zero issues.

The car went into storage in late October of '15 and ran like a top. Today after installing the battery I cranked the engine with the throttle floored (as is my usual practice after long-term storage) to circulate a bit of oil, then, after about 5 seconds, I release the throttle and the engine usually starts. This time it sputtered momentarily and just continued to crank. Several cranking attempts produced no firing at all. I pulled the #5 coil off and installed a plug and found a nice hot spark. I then checked the 20A fuel pump fuse (#14) under the hood and it's blown. I replace it with the 20A horn fuse and it immediately blows too.

I checked the wiring at the BAP in the back. There's a 30A fuse between the inertia cutoff switch and the BAP and that's fine (not blown.) The BAP is configured to run all the time (no pressure switch).

Not sure if I should suspect the BAP or the fuel pump or ...? The car was stored in a drive-shed of a farm along with numerous other cars. Perhaps rodents got into the wiring and chewed it, I don't know.

Curious of others' thoughts re what might cause that 20A under-hood fuse to blow with the BAP in there. I've read elsewhere that the 20A #14 fuse is often replaced with a 30A piece but my car's never needed it before.

 

[trinity_gt]

Looks like my BAP took a dump. If I removed the 30A fuse from the wiring near the BAP then fuse #14 doesn't blow telling me the wiring from the fuse block to the intertia switch is okay. I then bypassed the BAP in back effectively removing it from the circuit. Fuel pump ran, there was pressure at the rails and it fired up. So the pump, FPDM and wiring is fine. Everything points to the BAP as the problem.

I put the supercharger in "valet" mode (bypass valve held open) and have removed the BAP. Unfortunately, the BAP is completely potted internally so I can't see what, if anything has failed. I didn't try a 30A fuse at position #14 because (a) the car's wiring isn't made for that sort of current and (b) the car ran fine for years with the 20A fuse there.

Time to shop for a new fuel pump voltage booster.

 

[trinity_gt]

Took the BAP to work today and powered it on the bench from a 12V supply. Has a couple of amps of inrush current but unloaded it's only drawing 30mA and producing ~17.3V at the output suggesting the BAP may actually be okay.

So the plot thickens a bit. Will try adding a motor load to it and powering it from a 12V car battery to see how it behaves.

 

[trinity_gt]

Final update: The BAP appeared to work fine on the bench so I reinstalled it to day and the car runs fine with the OE-size 20A fuse under the hood. Took it out for a rip and at 9psi the AFR was around 11-11.5:1 (sometimes went even fatter < 11:1) so everything appears to be working peachy. At idle the pump & BAP were drawing ~3A of current. Under boost a clamp-meter set to peak showed ~10A. Nothing out of the ordinary.

I really hate "Heisenbugs" like this but will just sit on it until it strands me or the car goes a season hiccup-free.

I understand I can run a Focus SVT pump without the BAP for my mild set up (is this correct)? If so, maybe I can replace the pump and get rid of the BAP and kill two suspects with one stone.