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Old December 17th, 2014, 10:00 PM   #1
nitrousdave
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Location: Indiana
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Default a9l efi weirdness

Posted this on YB too, but thought it might get some more/different eyes over here:
I'm helping a local shop sort out an efi conversion they did on an old F100 truck. The truck fires right away in crank but dies as soon as cranking stops. Everything (efi wise) is supposed to have come from an 1989 mustang, the ECM is an A9L. I have verified all the grounds at the ecm connector, pin 1 goes to the battery positive, 37 and 57 have power in start and run. The coil, injectors, and EEC relay coil have power in start and run also. Made sure pin 30 was grounded as well. I even took the start/run power circuit and wired them directly to the battery and then jumped the solenoid and it still died when it stopped cranking. The run pin on the TFI has power in start and run and the start pin has power in start. The distributor is a replacement unit from napa so it and the TFI module are new. I have had the spout connector removed during all the testing, but from what I've read it should just run at base timing this way.
I haven't checked for codes yet since all the emssions stuff isn't hooked up and I'm sure it is setting some codes. I plan to check for codes when I go look at it again this weekend. I'm also going to take another TFI module and mass air sensor. Also going to take the cover off of the ECM and make sure there aren't any damaged traces on the board. I'll also look at the 5V for the sensors and check those circuits since that is one thing I haven't done yet.
I did some searching and found some people saying a bad MAF sensor can cause this. I also saw something about a bad sensor (ECT I think ) causing it not to run unless the throttle is open part way?
Any help or ideas would be appreciated as I'm pretty sure I've covered all the normal bases and am not well versed in the intricasies of how the A9L works. Thanks, Dave

Forgot to add that there is a separate low pressure pump in back (on a separate circuit) feeding the high pressure pump in front, so even if the front pump turned off I'm pretty sure the low pressure one would still force a little fuel to the injectors.
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