Hi, my dad just bought a 93 f-150 5 speed with the 4.9 I6 for $850. My brother also has a 91 with a 5 speed and 4.9. Anyways this truck has a pretty major engine problem. Here are the symptoms: hard to start (have to play with the throttle while starting and while running for 15 or so seconds), it back fires, cuts out really bad in 1st and 2nd gear when first running, after you drive for a little bit it does not cut out at all but idles up and down, and if you come back from a drive and shut it down and start it up again it will start right away no problem, but wait 5 minutes and it will be hard to start.
Now here are the things that we did, sea foam in oil and vacuum line, new air filter, fuel filter and castrol syntec oil with fram filter. the last owner said he did the plugs cap and wires but the plugs where hand tight and my dad thinks the cap is original. the guy also said he did the fuel pressure regulator but there does not seem to be a new one but a new part by the fire wall on a hose.

Sorry for the long first post but any help with this problem would be great, Thanks!

 

Get a scanner or click here

Go to any parts store and pick up a Haynes Manual.

Check the gap and condition of all the plugs and I would personally scrap the Fram oil filter and pick something else. Fram Oil Filters have CARDBOARD in the Cartridge End Caps. Source Check the wires and everything else the PO said he changed, if he didn't then I would test them and change if necessary.

 

we took out all the plugs and checked them, they are new and have correct gap. and the wires look good to. i tried with the scanner but i cant figure out how to convert beep and pauses to a trouble code.

 

If you can, you can record it and post it up here and we can give you a hand. If you click on the link I posted it will tell you how to determine the codes from the beeps or flashes.

 

he is going to bring it to auto zone to get it scanned. yesterday we installed a new throttle body gasket, cleaned the TB and intake, put new wires, cap and rotor, a new vacuum hose that was really bad and the new master cylinder the guy installed was leaking really bad so we put on a new one.

 

could these things cause the symptoms i said in the first post, ignition coil, coolant temp sensor, fuel pressure regulator? what would be the most likely?

 

Auto Zone can't scan your truck for codes.

 

ok well any ways, what do you thing about those parts i listed?

 

try checking the distributor, the control module on it may be bad.

 

Yes, they can cause your problem...but so could a big old fat Vacuum leak from that bad hose. You are headed in the right direction.

And get those codes.