I recently got a 96 f350 single cab 4x4 xl auto truck for great price, original paint in great shape, body straight, waxed it and shines like new. I did a tune up, heres all the new parts.

* spark plugs, rotor, dist. cap and bottom mount, throttle position sensor, map sensor, idle air control valve, fuel filter, full serviced tranny and motor oil/filter.*

The previous owner replaced water pump, distrubitor motorcraft, water jacket housing, cam chain, radiator.

Truck runs great and drives great. Heres the issue im having.

* when truck is cold or has been sitting for alittle while, when you start truck, it will start and has the normal high ford idle, then cuts out for maybe 1-2 second, then goes right back to idling down and idles and runs smooth after that. If you shut the truck off and restart within in a couple minutes, it will usually start normal and is smooth.*

Only thing I haven't replaced which I may tomorrow is the spark plug wires. I didn't replace them now since they look good. I always turn the a/c off before I shut truck off, so when I start truck and after it idles smooth, I turn a/c on, somethimes when a/c comes on, it idles truck down and it has cut the truck off. Vacuum lines look to be good, but is there a valve or sensor somewhere that im missing? Also, what could I do to get better mpg. I used to have a 94 f350 5spd 4x4 with 7.5 and don't remember that truck being as bad as this one. Thanks for all the future replys/help!

 

I'm no expert on these FI set-ups but last week I resurrected an old F350…

We found a similar problem… first we had a good start then the engine would stutter then either die or continue to run. the mechanic working on the truck replaced the fuel pump relay… didn't help. Then we noticed the idiot lites on the dash would blink when the problem occured. he replaced the ignition switch and bingo! we had it fixed.

Then, four miles and 30 minutes of run time the fuel pump died.

My advice would be to scan the system rather than throwing more parts at the problem… we tried that!

 

Both fuel pumps were replaced couple years ago from previous owner, have receipts for everything he did, which is good. I need to have it scanned, I don't have the scanner for obd1, have the obd2 readers. There's no lights on dash or any lights when it does that. Its gets expensive changing parts and it doesn't help, but the truck is a 96, so I figured the more I replaced, hopefully the better it runs and operates. Hope the key ignition is still good, its the original key switch, so I only need 1 key.

 

Just thought of something I found other day. The truck has cat back flowmaster muffler. The cat. convertor has been removed. Theres a tube running from motor along exhaust pipe and then you can see where it has been cut with a cutting torch. Would this have anything to do with how truck would run and perform? mpg? Also, what would be the best, cheapest, simplest way to improve fuel mileage?

 

Buy a cheap 4 cylinder beater

It really is the easiest and probably cheapest in the long run. You have a huge, thirsty and heavy truck with the aerodynamics of a barn that is also saddled with one of the largest production gas engines. At best you may get mid-teens if you drive unloaded and stay under 60 MPH.

My old '92 F350 4x4 w/5.8L and 3.55 gears never got above 12 MPGs under any driving conditions, it only went down from there.

 

the truck sits under carport most of the time, only used on weekends or when I need to pull gooseneck. After I replaced the manifold pressure sensor, it fixed the starting issue I had. Now when I start the truck, it starts no problem, but when I turn on the a/c, it makes the motor idle rough/low and then picks back up. This is when the truck is cold or hasent been ran for alittle bit. Its not a huge problem since it still runs good, I just want it to be right. Is there a sensor that controls the idle for the a/c?

 

late reply. I found out the fire order was wrong and timing was off. Put spark wires right on distributor, unplugged advance and was way off on time. Guess previous owner didn't unplug advancement when he timed it or knew the fire order. Truck idles very smooth and will spin the tires very easy now. Every now and then when its cold, or only been ran for few minutes, it will start up, idle rough, cut out like and smooth out. Once truck is warm, it starts with no issues. Also, using seafoam as a motor flush before I change my oil, is that a good ideal since it has 242k miles?

 

Seafoam is good stuff but if the engine has had regular oil changes I don't think it's needed. These EFI deals run pretty clean if the maintenance is kept up.