94 mustang rough idle/ code 543

rcodenewf

New Member
Aug 11, 2005
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Just put my son's 347 together and tuned it with a tweecer. Took it to the dyno and made 348hp 378ft/lbs at the wheels. Took the car home. shut it off and upon restarting it , it died. Several attempts and it died. After crippling it home we checked the tune and it appeared okay, but several codes were removed with an OTC scan tool. A couple of those were related to the egr and air pump which are removed and the program has them written out.
Code 543 (Fuel pump circuit open; battery to pcm) keeps appearing. Fuel pump appears to be okay. I can hear it whine when the key is on.
Engine runs very rough, shakes, hunts, and is hard to start.
I removed the tweecer and now the problems are still there. I just wanted to isolate the tweecer. I've checked TPS voltage, timing, vacuum leaks, injectors, plugs appear great in colour, i've disconnected the o2's, rechecked all the connectors.
One thing i did notice when the car first came home was that the negative battery terminal was very loose and just about falling off. My son and the tuner had removed it to take the tweecer out for tuning. I'm thinking that with the loose terminal it may have ****ed the EEC. Any ideas? How about the 543 code?
I've also checked out the inertia switch in the trunk. Sometimes they get corrosion and go bad.
Grounds are good and i've used jumpers to confirm this.
Specs are 347, 75mm Pro M cal. to 30lbs, trick flow track heat intake and heads, stock dist, long tube headers, xe274hr cam, 9.3, air, etc.
Any help would be appreciated as I'm just about ready to throw in the towel on this one.:-?:-?
 
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