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1990 4.9 got me stumped

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Old 12-01-2017, 10:13 AM   #1
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Default 1990 4.9 got me stumped

I am trying to revive this truck for a friend of mine, and it has been sitting for 10 years. Changed oil, filter, gas filter, dist cap, plugs, and wires, fresh ags in front tank. It ran like a champ when I test drove it. Called my buddy and he came over and tried to start it and it ran like CRAP! didn't do anything to it between my test drive and him trying it. Eventually found a bad fuel pressure regulator, replaced that and it's better but still no joy. Pulled the injectors ald cleaned and tested them and they SEEM to be fine. Still runs rough, pulled the plugs and they were ALL carbon fouled. Checked all my vacuum lines and can't find a vacuum leak. Any suggestions? Thanks in advance for any help.
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Old 12-03-2017, 07:50 AM   #2
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As poorly as its running, I would check for codes before doing anything. Seems there is a ton of fuel being administered.
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Old 12-06-2017, 07:44 PM   #3
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Welcome to the site!
Agree with the suggestion to pull the computer codes. Also, suggest to check the fuel rail pressure to verify it's at least 40psi, 45 preferred.
Good luck and keep us posted.
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