Frustrating Crank/No Start situation on 2010 Mustang

Juice

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Hadn't thought about the gas cap. Will try that next time it won't start. Only electrical mods were adding larger gauge power wire to the FPDM and a higher capacity fuel pump. Otherwise stock.
Since it is returnless, dont worry about checking the gascap. Since there is no return, the fuel is not being heated by any return. Unless its holding vacuum and not venting as fuel is used up.
 

DieHarder

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Hey Guys, finally got some time to troubleshoot my fuel issue. As I've said in the past I have a DOB kit so it's slightly different from stock; larger gauge wiring runs from the battery to a relay near the FPDM and it has a custom/higher volume fuel pump compared to stock. Long story short I tried to start the car when I got home yesterday but this time it failed hard (which truth be known I'd rather deal with total failure than something that appears it's working properly for a while and then fails at the worst possible time). Anyway, decided to half-step the fuel system starting with the FPDM after I learned the fuel pump wasn't pressurizing. Mine is so quiet you can't hear it come on but you can feel it at the rubber diaphragm (for about 5 seconds) if you take the rear seat out and go KOEO. In this case no fuel pump priming.

Took the spare tire out and associated covers and noticed that the SPST power relay you have to add (part of the DOB kit) to run 12v from battery pos to the FPDM (to supply the higher volume fuel pump) had separated from its case and was just hanging near the FPDM. Thought, hmmmm...that's interesting. So, once I got it out it still looked okay and after I put the guts back into the case it worked again but figured might as well go get a replacement. Of course, the auto parts store has only one in stock; and they want $18 for it. Jeezus, I told the guy it was highway robbery as I can buy these things all day long for under a dollar (just got to wait for it). Still, figured it was a cheap fix so bought it, went home, hooked it up and of course everything is back to normal. I did go online and order 3 more (.97/ea; shipping $9); just in case I ever need to replace another (high likelihood I never will).

Moral of the story.... look for mechanical damage as well as trace out things electrically. And half-stepping if you have half-a-clue can save a great deal of time. Anyway, that's my words of wisdom for the forum today. Oh yeah, and stay away from carpet-bagging auto stores; what a rip-off!
 
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