Hey all, I'm completely new to the world of Ford, and just recently picked up a '96 F250 from a friend of mine. It drove home just fine, and for a couple days after that it had no problems getting around town. One day, I hopped in, started her up and it ran great for about 15-20 seconds, then shut off. No sputtering or rough idle, just like I turned the ignition switch off.

I tried to start back up right away, but it just kept trying to turn over. I had to wait about a minute before it would fire again, but then it shut off just like the first time. I can hear the fuel pump come on when I turn the switch to the on position, then shut off after a few seconds. It does the same thing on both fuel tanks.

I replaced the fuel filter, but it still does it. Anyone have any idea what the issue might be?

 

Is your check engine light on?
This is where we will always start troubleshooting.
Have you checked all your fuses, including under the dash and under the hood?

 

No, there's no CEL, that was the first thing I looked for. I'll check the fuses next.

 

dont 89's have 2 fuel pumps ? mine does on a 460. low pressure in tank, and high pressure on the frame, check that pump

 

If the computer doesn't get a signal that says that the engine is running, it won't restart the fuel pump after the initial 2 second squirt. That would probably make it quit after a few seconds.

So, try to find out if your fuel pump comes back on after the initial squirt.
If it doesn't, that might be your problem. (BTW, I think that ford got rid of the inline fuel pump after 1990 or so. You should only have in tank pumps.)

I don't know what that signal is, but you might be able to find out in the manual or at fordfuelinjection.com.

 

So, many months later...

The later models of these trucks don't have the two pumps, just the in-tank FDMs. Sooo...

I've replaced the fuel filter, fuel pressure regulator, and front tank fuel pump. Nothing changed. It runs for 18 seconds at the most.

Then I replaced the coil pack. *That* doubled the time it will run...which was weird. So we figured it was the ICM going bad...so I replaced that. Didn't work.

Sooo...I'll be looking for that "engine running" signal now...

 

So after more testing...

I have lots of spark, plenty of fuel pressure, and the fuel pump relay is staying energized.

The fun part is that we can keep the engine running by spraying starting fluid into the intake. So something is telling the computer to turn off the injectors...*after* a time delay.

So, as stated before, it runs for about 35 seconds after sitting for a while. Trying to start it right away doesn't work. If I let it sit for a minute, I'll get 8 seconds or so, and the longer it sits the longer it runs, up to 35 seconds.

Does anyone know of anything that would tell the computer to shut off the injectors, that would require a cool down period or act like this?

 

Sounds like my truck has a twin
I have almost the same problems with my 1994 F-150 5.0. Mine went off during driving. When i pulled the connector from the MAF Sensor the truck runs excellent. Putting the connector back, the engine dies
Trying to restart lets it run 2 seconds then goes off again.
Please let me know when you find the problem on your truck. Maybe its the same with mine
Robert

 

Well, the MAF sensor *was* bad, but replacing it didn't change the issues I was having. I've diagnosed as far as I can. I ended up taking it to the shop I use for all of my vehicles that I just can't figure out. *They* thought they'd have it done in a few hours. They've had it 2 days now. So even they're having issues. I'll know more when I get it back...hopefully soon.

 

definetly let us know how this turns out and what the problem was

BigLar

 

So.

My mechanic called today. They checked the injectors one by one to see if any had shorted out to cause the issue. No dice. Apparently they checked the PCM. It's bad. So a new computer it is. If that really is the issue, I'll have it tomorrow.

Update to follow...

 

any news here ?

 

please post what the mechanic found, my problem is similar.

thanks,

 

I had a similiar problem on my 1996 f250. my truck would just randomly die. sometimes it would start and sometimes not. In my case it turned out to be the pip sensor in the dist. I just replaced the dist. and havent had any problems since. Not sure if a 89 uses the same parts or if a 91 does but the computer needs that signal to turn the fuel pump back on i believe. my truck also threw a code for it.

 

it is a 1996 not a 1989.