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1987 - 1996 F150 & Larger F-Series Trucks 1987 - 1996 Ford F-150, F-250, F-350 and larger pickups - including the 1997 heavy-duty F250/F350+ trucks

Pickup not starting

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Old Jun 2, 2012 | 05:43 PM
  #1  
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Pickup not starting

1988 F150, 5.0, 2wd, Auto

Drove it to work yesterday, CE light came on, stumbled at a stop light, then started idling high, about 1400, pulled into work, popped the hood, pulled off the connector to the IAC, it dies. Plug it back in and start it back up just fine, still idles high.

Couple hours later I go to drive it home to plug in my code reader, now it won't start. Grabbed the work rig and went home to grab my code reader, plug it in and nothing, wont connect. I work at Autozone so I grabbed the one we have on the shelf, has a flashing light and beeps, it just constantly beeps when you plug it in, so I think the diagnostic connector is busted.

Also both pumps are running all the time when the key in on, they don't shut off.

I have tested the pressure at the rail and have 40 psi.

I am getting spark. Tried a new fuel pump relay, same.

Could my ECU just up and puke like that? What else controls the pumps and the fuel injector pulses?

Any ideas?
 
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Old Jun 2, 2012 | 05:57 PM
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Well since you tried a new pump relay I would say the ECU relay is closed or you have a ingnition switch issue.

Is the old pump relay still in there?
 
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Old Jun 2, 2012 | 06:43 PM
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Yup, pulled a new one and threw it in, didn't change so I put the old one back in.

Is the ECU relay the one right next to the fuel pump relay? I plugged the new relay into both and no change. Which is which? There are green and brown connectors
 
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Old Jun 2, 2012 | 08:42 PM
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Is the check engine light on when you turn the key on? Sounds like you may have had an ECU failure. Some of these Ford computers run into capacitor issues as they age.
 
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Old Jun 2, 2012 | 08:59 PM
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Yeah its on.

Did anything change from 88 to 91? I have an ECU from my other pickup when I swapped it to MAF. Is the AOD from 88 computer controlled? The ECU is out of a manual
 
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Old Jun 2, 2012 | 09:03 PM
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Sounds like the clock stopped in the computer. Some have replaced the crystal to get the computers clock running again.

The clock has to run to get the fuel pumps to time out and stop after one second and you also need the clock to fire the injectors.

The fuel pump will not run if the EEC power relay is bad.

No an AOD is not computer controlled.
 
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Old Jun 3, 2012 | 12:30 PM
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Well, I threw the ecu from my 91 from when I did the MAF swap, pickup fired right up like normal. Good thing I don't throw anything out. Problem solved
 
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Old Jun 3, 2012 | 02:06 PM
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Good for you. Now what?
 
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